Tag: niacinamide

  • Dark Circles in Korea: A 0-5 Grade Scale in the Test Guideline, and No Claim Category in the Notified List (Skin Concern Series)

    Cover image for an article on dark circle ingredients in Korea. Annex 4 of the functional cosmetics notification lists six claim categories and the word dark circle does not appear in it; the nearest box is whitening with nine actives. Chapter 6 of the Korean MFDS guideline on test methods for substantiating claims instead writes down the procedure: the test site is the dark-circle area under the eye, melanin index is read with a Mexameter MX18 and lightness L star with a Chromameter CR-400, and at least twenty valid data sets are required. Dr. J Ingredient Notes.

    🇰🇷 한국어판

    Hello, this is Dr. J. Today I want to look at dark circle ingredients the way Korean regulators look at them — and at what the human studies actually moved.

    Two things surprised me. The word “dark circle” does not appear in Annex 4, the table that fixes actives and levels for notified functional cosmetics. And yet the Korean regulator wrote down how to measure one, down to a 0-5 grade scale that two experts apply by eye.

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    Primary sources

    📄 MFDS, Guideline on Test Methods for Substantiating Cosmetic Claims (Mar 2018, PDF, Korean)

    📄 Regulation on Functional Cosmetics Review, Annex 4 (Korea Law Service)

    📄 Phytonadione, retinol and vitamins C and E, 8 weeks (J Cosmet Dermatol 2004)

    📄 Vitamin C on dark circles, 6 months, split face (Skin Res Technol 2009)

    📄 U.S. FDA, Cosmetics Labeling Claims

    The guideline covers ten claims. Chapter 6 is dark circle relief.

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    Five lines, if you are in a hurry

    ● Annex 4 has six claim categories and dark circles is not one of them

    ● The nearest box is whitening, with nine notified actives — the pigment side

    ● Chapter 6 of the test guideline writes down how to measure the area under the eye

    ● It names the instruments and attaches a 0-5 expert grade scale

    ● But in the two eye-area studies, what moved was the vascular reading, not pigment

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    There is no box for it — Annex 4 and its six categories

    Annex 4 of the Regulation on Functional Cosmetics Review lists, for each claim category, the actives and the levels that let a manufacturer skip submitting new efficacy data. It is a shortcut list, not a safety list.

    There are six categories. I opened the original today and searched it: the word “dark circle” is not in the table.

    Category in Annex 4 What the notification fixes How to read it
    UV protection / tanning Actives and maximum levels Both the name and the number are set
    Whitening Nine actives (arbutin 2-5%, niacinamide 2-5%, and others) The nearest box to today’s topic
    Wrinkle improvement Four actives (retinol 2,500 IU/g, adenosine 0.04%, and others) The subject of the previous article
    Hair colour change Dyeing, bleaching and de-dyeing actives Hair, not skin
    Hair removal Thioglycolic acid and others Depilatories
    Acne-prone skin relief Salicylic acid 0.5% Covered in an earlier article
    Dark circles — There is no such category

    The nearest box is whitening, with nine actives

    Pigment is one of the reasons the under-eye area looks dark, and pigment is what the whitening box covers.

    Notified whitening actives (nine) Level
    Broussonetia extract 2%
    Arbutin 2-5%
    Ethyl ascorbyl ether 1-2%
    Oil-soluble licorice extract 0.05%
    Ascorbyl glucoside 2%
    Magnesium ascorbyl phosphate 3%
    Niacinamide 2-5%
    Alpha-bisabolol 0.5%
    Ascorbyl tetraisopalmitate 2%

    Two names in this table come back later in this article: ascorbyl glucoside and niacinamide.

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    What exists instead — Chapter 6 of the test guideline

    The MFDS guideline on test methods for substantiating claims (March 2018, document no. 0353-02) sets out how to test ten advertising claims. Chapter 6 is dark circle relief, and it was added in August 2014.

    Chapter Claim When it was added
    Ch. 1-3 Skin moisturising · Skin elasticity · Sebum control May 2012, original
    Ch. 4-5 Temporary cellulite reduction · Suitability for acne-prone skin Nov 2013
    Ch. 6 Dark circle relief Aug 2014 (B2-2014-4-003)
    Ch. 7-8 Blood circulation · Puffiness relief Dec 2015
    Ch. 9 Paraben-free 31 Mar 2017
    Ch. 10 Fine-dust protection 28 Mar 2018

    Chapter 6 — what is measured (the guideline’s own wording)

    1. “Melanin content of the skin is measured and the change in melanin index is evaluated.”
    2. “The L* value of the pigmented site is measured and the change is evaluated.”
    3. “The whole face is photographed at a fixed angle and distance, and Red, Green and Blue values are obtained with image analysis software to derive a quasi L* value.”
    4. “Two or more experts closely observe the dark-circle area and grade it according to the dark circle grade (Grade 0-5) in Table 1.”

    Chapter 6 — how it is run and how it is judged

    “The test site shall be the dark-circle area under the eye.”
    “The number of subjects shall be 20 or more so that statistical comparison is possible, securing valid data.”
    “Adults aged 20 or over shall be selected …”
    “After cleansing, subjects rest for 30 minutes under controlled conditions (20-24 °C, 40-60% RH) before measurement.”
    “Repeated measures ANOVA is evaluated for statistical significance at the 95% confidence interval (p<0.05).”
    “If one or more of the evaluation indices shows relief of dark circles after use of the test material, the product is judged to help relieve dark circles.”
    The study length is “recommended to be about 8 weeks”, and application follows the product’s own directions.

    Read closely, the judgement is on the permissive side: if one or more of the four indices improves, the product is judged to help.

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    The part that surprised me — a 0-5 grade scale for a shadow

    Chapter 6 attaches a table that two or more experts use to grade the area by eye. Here it is in full.

    Grade What the guideline writes (translated from the Korean text)
    0 No dark circle is perceived
    1 A faint purplish shadow in the inner lower eyelid, judged a dark circle because the colour deepens when the skin is pulled
    2 A purplish shadow clearly visible without pulling the skin, or mild pigmentation, or both together
    3 A deep purplish shadow, or moderate pigmentation in part of the area, or both together
    4 Uniform, strong pigmentation overall, sometimes seen above and below the eye at the same time
    5 Uniform and very strong pigmentation seen above and below the eye at the same time

    Grade 1 is the interesting one: the shadow counts as a dark circle because the colour deepens when the skin is pulled. Pull the skin and it darkens, and you are closer to a shadow; stays the same, and you are closer to pigment.

    Grades 4 and 5 say “above and below the eye at the same time”. Even within one claim, the scale looks at different places as it climbs.

    Evidence summary for dark circle ingredients. First, there is no dark-circle box in the notified list: the six categories are UV protection and tanning, whitening, wrinkle improvement, hair colour change, hair removal and acne-prone skin, and the nearest box is whitening with nine actives including niacinamide at two to five percent. Second, the test method is written down in Chapter 6 of the MFDS guideline, with the test site under the eye, melanin index by Mexameter MX18, lightness L star by Chromameter CR-400, photographs by Visia-CR, expert visual grading from zero to five, at least twenty valid data sets, adults aged twenty and over, twenty to twenty-four degrees and forty to sixty percent humidity with thirty minutes of rest, and repeated measures analysis of variance at p below 0.05. Third, two actives moved the vascular reading: in fifty-seven Japanese adults over eight weeks, an open-label gel with phytonadione two percent, retinol zero point one percent and vitamins C and E improved the vascular component in twenty-seven of fifty-seven, that is forty-seven percent, while pigmentation was not clearly removed. Fourth, two vitamin C forms split apart: in fourteen subjects over six months with a split-face vehicle control, sodium ascorbate ten percent showed a significantly smaller change in erythema index than the vehicle side, while ascorbyl glucoside showed no difference from vehicle in erythema, melanin or dermal thickness. Fifth, what was left out and why: niacinamide stopped at the notified two to five percent because no eye-area trial could be opened, a caffeine and vitamin K study used an eye pad rather than a cream, laser, filler, mesotherapy and peels are procedures, and a trademark-ingredient serum trial names ingredients that cannot be found on a label.

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    Two that moved the vascular reading — vitamin K and retinol

    57 Japanese adults with infraorbital dark circles and lower-eyelid wrinkles applied a gel twice daily for 8 weeks — the same length Chapter 6 recommends.

    The gel contained phytonadione (vitamin K1) 2%, retinol 0.1% and vitamins C and E at 0.1%.

    After 8 weeks the vascular component improved in 27 of the 57 (47%), and wrinkles decreased in some subjects. Pigmentation was not clearly removed.

    The weak points belong here too: the study was open label, and with four actives in one gel the shares cannot be separated.

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    Two vitamin C forms that split apart

    14 subjects with dark circles applied sodium ascorbate 10% under one eye and the vehicle under the other for 6 months.

    On the sodium ascorbate side, the change in erythema index was significantly smaller than on the vehicle side. Dermal thickness trended upward but did not reach significance.

    In the same study, ascorbyl glucoside showed no difference from vehicle in erythema index, melanin index or dermal thickness.

    They are both vitamin C derivatives, and ascorbyl glucoside is one of the nine notified whitening actives, at 2%. Being on the notified list and moving a number under the eye are two different things.

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    The one the notified list puts on the pigment side — niacinamide

    Niacinamide 2-5% sits in the whitening box, so a Korean product can carry a reviewed whitening claim with it.

    I could not open an eye-area trial for it as a primary source today, so this article stops at the notified level rather than implying more.

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    The five in one table

    Ingredient People and time Design What was measured Result
    Vitamin K (phytonadione 2%) 57 Japanese adults · 8 weeks Open label · twice daily Vascular score, pigmentation, wrinkles Vascular score improved in 27 (47%)
    Retinol 0.1% Same study In the same gel Same measures Wrinkles decreased in some subjects
    Sodium ascorbate 10% 14 subjects · 6 months Split face · vehicle control Erythema index, melanin index, dermis Change in EI significantly smaller than vehicle
    Ascorbyl glucoside Same study Same design Same measures No difference from vehicle
    Niacinamide 2-5% — — — Notified level for whitening, nothing more here

    Where each study is weak

    Ingredient Where it is weak
    Vitamin K and retinol Open label, with no placebo arm in the abstract. Four actives sat in one gel, so the shares cannot be separated. Pigmentation was not clearly removed
    Sodium ascorbate Only 14 subjects. No p value in the abstract, and the dermal thickening was not significant
    Ascorbyl glucoside Its concentration is not given in the abstract. The null result itself is clear
    Niacinamide No eye-area trial could be opened as a primary source today, so this article stops at the notified level

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    Korea, the United States and the EU

    None of the three keeps a list of actives for dark circles. What differs is whether the regulator writes down how to measure it.

    What a dark circle claim rests on Who writes the test method
    Korea No box in the notified list. The claim is substantiated afterwards (Cosmetics Act Art. 14) The government does — Chapter 6 names the instruments, the room conditions and a 0-5 expert grade scale
    United States There is no list of approved claims at all — “FDA does not have a list of approved or accepted claims for cosmetics” Nobody. The agency also states it has no authority to approve claims before marketing
    EU The six common criteria of Regulation (EU) No 655/2013 Nobody — only the conditions: “adequate and verifiable evidence” and “state of the art practices”

    For an exporter the practical line is short: in Seoul the question is how you measured it, in Brussels and Washington the question is what evidence you hold. Korea is unusual in writing the instruments, the room conditions and a grading table into a public document for a claim it does not pre-review.

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    Five things to check on a label

    ✔ Ask first what is dark — pigment, visible vessels, or a shadow

    ✔ In front of a mirror, pull the skin gently: if the colour deepens, you are closer to the shadow side (that is Grade 1’s own wording)

    ✔ A whitening functional claim means one of the nine notified actives, on the pigment side

    ✔ A “dark circle” claim is substantiated, not pre-reviewed — the procedure lives in Chapter 6

    ✔ Where an advertisement shows a number, look for how many people, how many weeks, and which index

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    One line

    Korea wrote the ruler and the grading table, but never opened a box for the claim — and the two eye-area studies moved the vascular reading rather than the pigment one.

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    What I left out, and why

    ✔ A caffeine 3% and vitamin K 1% study (Adv Biomed Res 2015, 11 women, 4 weeks) — the product was an eye pad, not a cream, and the report carries no figures or p values

    ✔ Laser, filler, mesotherapy, PRP and peels — procedures. On this topic they fill most of the search results

    ✔ A single-arm serum trial (J Clin Aesthet Dermatol 2022, 85 completers, 3 months, melanin index down 12.29%, p<0.05) — the only study here that measured melanin under the eye directly, but its actives are trade names that a reader cannot find on an ingredient list, there was no placebo arm, and the manufacturer funded it

    ✔ Mechanism paragraphs (vascular permeability, haemoglobin breakdown, melanosome transfer) — I did not open a primary review, so I did not write them

    ✔ Folk wisdom — “dark circles come from lack of sleep” and “tapping helps” have no primary source here

    About the author · Dr. J

    MS in Veterinary Medicine, PhD in Life Sciences. I worked as a researcher at the Korea Research Institute of Bioscience and Biotechnology (KRIBB) and now run Beaurea, a cosmetics manufacturing company, where I write the formulas myself. This blog reads the research papers and the regulatory documents and turns them into plain-language criteria for choosing ingredients. I don’t recommend specific products here – only criteria that apply to any product.

    📌 Related reading

    📌 Firmness actives in Korea: wrinkle is notified, elasticity is substantiated — Chapter 2 of the same guideline

    📌 Pores and sebum: the test method the regulator wrote down — Chapter 3 of the same guideline

    📌 Niacinamide: how much is enough — the notified 2-5% in detail

    📌 Not all vitamin C serums work — the two forms that split apart today

    📌 Retinol: start at 0.1% — the concentration that sat in today’s gel

    📄 References

    · Regulation on Functional Cosmetics Review, Annex 4 (Korea Law Service, accessed 22 Oct 2026)

    · Ministry of Food and Drug Safety, Guideline on Test Methods for Substantiating Cosmetic Labelling and Advertising Claims (civil petitioner guide, Mar 2018, no. 0353-02), Chapter 6

    · Mitsuishi T, Shimoda T, Mitsui Y, Kuriyama Y, Kawana S. J Cosmet Dermatol 2004;3(2):73-75

    · Ohshima H, Mizukoshi K, Oyobikawa M, Matsumoto K, Takiwaki H, Kanto H, Itoh M. Skin Res Technol 2009;15(2):214-217

    · U.S. FDA, “Cosmetics Labeling Claims” (content current as of 21 Nov 2022) · Regulation (EU) No 655/2013 · Regulation (EC) No 1223/2009 Art. 14

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    This article summarises published research and Korean regulatory documents; it is information, not diagnosis or treatment. Annex 4 and Chapter 6 were read in the original today, and the quoted Korean passages are my translation of that text. Of the two eye-area studies, one was open label with four actives in a single gel and the other had 14 subjects and no p value in the abstract — both facts are in the tables above. Ingredient names and levels are written as criteria for choosing a product, not as a recommendation of any particular one.

    — Dr. J Ingredient Notes

  • Sensitive Skin Ingredients: The Category No Regulator Names, and Five with Human Studies

    Cover image for a guide to sensitive skin cosmetic ingredients in Korea. Korea's Regulation on Review of Functional Cosmetics, Annex 4, notifies actives in six categories: UV protection with 27 ingredients, brightening with nine, wrinkle improvement with four, hair colour change, hair removal with thioglycolic acid, and acne relief with salicylic acid at 0.5 percent. Sensitive skin is not one of them. The Ministry of Food and Drug Safety guideline on test methods for substantiating cosmetic claims sets out ten methods, and sensitive skin is not among those either; people with sensitive or hyper-reactive skin are instead screened out of those tests. In the United States there are no federal standards or definitions for the term hypoallergenic, and in the European Union the only permitted lists of ingredients are for colorants, preservatives and UV filters. Five ingredients with human studies fill the gap: ceramide, panthenol, colloidal oatmeal, licochalcone A and niacinamide. A Dr. J Ingredient Notes cover.

    🇰🇷 한국어판

    Hello, this is Dr. J. Today I want to pick five ingredients for sensitive skin the only way that is left — from studies done on people.

    One thing first, because it sets up everything else. Sensitive skin barely appears in the rules at all. Where it does appear, it is not as something to measure. It is a reason to exclude someone from a test.

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    The sources, first

    📄 Regulation on Review of Functional Cosmetics, Annex 4 (Korean Law Service)

    📄 MFDS, Guideline on Test Methods for Substantiating Cosmetic Claims (2018-03, PDF)

    📄 U.S. FDA, “Hypoallergenic Cosmetics”

    📄 Regulation (EC) No 1223/2009, Article 14

    Six categories in the Korean annex, ten methods in the guideline. Sensitive skin is in neither.

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    Five lines, if you are in a hurry

    ✔ Korea notifies actives in six categories, and sensitive skin is not one

    ✔ The MFDS test-method guideline lists ten methods, and sensitive skin is not one either

    ✔ In those tests, sensitive skin is an exclusion criterion

    ✔ The United States wrote a definition for “hypoallergenic” in 1975 and lost it in court

    ✔ So five ingredients are picked here from human studies, weaknesses included

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    What Korea names, and what it leaves out

    Korea’s functional cosmetics system works from a notified list. Annex 4 of the Regulation on Review of Functional Cosmetics sets out the ingredient and the amount. Make a product to those numbers and you do not have to file fresh efficacy data — which is another way of saying the state has already decided what counts.

    Category What the notification sets out How to read it
    UV protection 27 ingredients with maximum amounts Names and numbers are both fixed
    Brightening Nine ingredients (arbutin 2–5%, niacinamide 2–5% and others) Same
    Wrinkle improvement Four ingredients (retinol 2,500 IU/g, adenosine 0.04% and others) Same
    Hair colour change A dyeing list split across six sub-tables Same
    Hair removal Thioglycolic acid, 3.0–4.5% as the acid, pH 7.0 to under 12.7 One ingredient
    Acne relief Salicylic acid 0.5%, in cleansing products One ingredient
    Sensitive skin Nothing There is no such category

    Acne gets one ingredient. Sensitive skin gets no category at all. So “for sensitive skin” and “low irritation” on a Korean box are not reviewed phrases.

    Evidence figure on sensitive skin ingredients. First, Korea notifies actives by category. Six categories each carry named actives and set amounts: UV protection 27, brightening nine, wrinkle four, hair colour, hair removal with thioglycolic acid, and acne with salicylic acid 0.5 percent. Sensitive skin is not one of the six. The source is the Regulation on Review of Functional Cosmetics, Annex 4. Second, sensitive skin is not in the test-method guideline either. The Ministry of Food and Drug Safety guideline sets out ten test methods covering moisturising, elasticity, sebum, dark circles, fine dust and others, and sensitive skin and low irritation are not among the ten. Instead people with sensitive or hyper-reactive skin are an exclusion criterion in those tests. Third, the United States had a definition and lost it. FDA proposed a hypoallergenic rule in February 1974 and issued the final regulation on 6 June 1975, but an appeals court held the definition was unreasonable. FDA now writes that the term means whatever a particular company wants it to mean and that there are no federal standards or definitions governing its use, as of 25 February 2022. Fourth, the European Union names actives for three jobs and not for claims. Article 14 of Regulation 1223/2009 bans colorants not listed in Annex 4 and does the same for preservatives and UV filters in Annexes 5 and 6, and no annex is a permitted list of actives for a claim. Claims instead need adequate and verifiable evidence under Regulation 655/2013. Fifth, the human studies have to do the work: ceramide with 50 subjects over four weeks in a single arm, panthenol 5 percent with 25 enrolled over 26 days in a randomised placebo-controlled trial, colloidal oatmeal with 29 women investigator-blinded, licochalcone A with 1,221 subjects over four weeks in an open study, and niacinamide with 50 women over four weeks with one forearm untreated. Two of the five had no control group and one did not report its duration.

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    There is no method to measure it either

    This is the part that is specific to Korea, and it is worth knowing if you sell there. The MFDS publishes a separate guideline that tells you how to run the test behind a claim — which instrument, how long, what unit. Each claim gets its own chapter.

    Chapter Test method Added
    1 Skin moisturising 2012-05, at issue
    2 Skin elasticity 2012-05, at issue
    3 Sebum control 2012-05, at issue
    4 Temporary reduction of cellulite 2013-11
    5 Suitability for acne-prone skin 2013-11
    6 Dark circle improvement 2014-08
    7 Skin blood-flow improvement 2015-12
    8 Puffiness reduction 2015-12
    9 Paraben-free 2017-03-31
    10 Fine-dust blocking 2018-03-28
    — Sensitive skin, low irritation Not among the ten

    Moisturising is there. Sebum is there. Dark circles are there. Sensitive skin is not.

    ★ The one place “sensitive” does appear

    In the subject-selection rules for chapters 1, 2 and 3 — moisturising, elasticity and sebum — one of the exclusion criteria is “people with sensitive or hyper-reactive skin”. Chapter 5, on acne-prone skin, excludes “people whose skin is sensitive to adhesive components”.
    So in this document sensitive skin is not something you measure. It is something you screen out before you measure anything else.

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    The United States tried, and the courts said no

    The American story is the sharpest of the three, because the definition existed and then stopped existing.

    When What happened Where it stands
    February 1974 FDA proposed a regulation on the term hypoallergenic A definition was on the table
    6 June 1975 FDA issued the final regulation Manufacturers would have had to test
    On appeal The court held FDA’s definition was unreasonable The regulation fell
    Today «There are no Federal standards or definitions that govern the use» «The term means whatever a particular company wants it to mean»

    FDA’s own page puts it plainly: «There are no Federal standards or definitions that govern the use of the term “hypoallergenic.”» And then, one sentence later: «The term means whatever a particular company wants it to mean.»

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    The EU names actives for three jobs, and claims are not one of them

    It is easy to assume the EU, with its long annexes, must have a list somewhere. It does not — not for claims.

    Annex What it is What that means for a claim
    Annex II Prohibited substances A list of what cannot go in at all
    Annex III Restricted substances Conditions, not a permitted list
    Annex IV Colorants — permitted list A colorant not listed cannot be used
    Annex V Preservatives — permitted list Same
    Annex VI UV filters — permitted list Same
    For a claim No annex Evidence under Reg. 655/2013 instead of a list

    Article 14 is a list of prohibitions. Three of them work as permitted lists, because a colorant, a preservative or a UV filter that is not in its annex cannot be used. There is no fourth annex for “soothing” or “for sensitive skin”. Under Regulation (EC) No 655/2013 a claim has to rest on «adequate and verifiable evidence» instead, and the method is left to «state of the art practices».

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    So the studies have to do it

    That is the whole argument for reading the trials themselves. Here are the five, with the size, the length and the design next to each.

    Ingredient People Length Design Measured Number
    Ceramide 50 4 weeks Single arm, no control Hydration, TEWL Hydration median 50 to 80
    Panthenol 25 enrolled
    21 finished    		 26 days Randomised, double-blind, placebo-controlled Hydration after irritation Better on the active side in 11, placebo in 1
    Colloidal oatmeal 29 women Not reported Investigator-blinded Dryness, scaling, roughness, itch All four improved
    Licochalcone A 1,221 4 weeks Open study, no control Redness and related scores P<0.001
    Niacinamide 50 women
    46 finished    		 4 weeks One forearm untreated, investigator-blind TEWL, capacitance TEWL 2.5 vs 3.9

    The last row is worth a pause. Niacinamide sits on Korea’s brightening list at 2–5%. This study measured something else entirely — barrier. The ingredient name does not tell you what was measured.

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    And where each one is weak

    Ingredient Where it is weak How to read it
    Ceramide No control group, one site, manufacturer-funded Read what was measured, not the size of the change
    Panthenol Only one endpoint reached significance The design is the strongest of the five
    Colloidal oatmeal The abstract does not give the duration Read it without knowing how long
    Licochalcone A No control, and the product also contained trans-4-t-butylcyclohexanol The two cannot be separated here
    Niacinamide The facial figures were not tested statistically Read the forearm numbers

    Of the five, one design is clearly the strongest, and it is the smallest study. Twenty-five people, randomised, double-blind, placebo-controlled, with the irritation deliberately induced. The study with 1,221 people has no control group at all. Size and strength are not the same thing, and a box never prints either.

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    Four things to check on the box

    ✔ Look past “for sensitive skin” and check whether the five names are in the ingredient list

    ✔ The earlier a name sits in that list, the more of it is in there

    ✔ Photograph the names after “fragrance” so you can compare them later

    ✔ Try anything new on the inside of your arm for a few days first

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    One line

    No regulator in these three places names an ingredient for sensitive skin, so the studies have to. Decide first whether your issue is barrier, itch or redness, and five becomes three.

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    What I left out, and why

    ✔ Centella asiatica and madecassoside — I could not open a human study, only reviews

    ✔ “Fragrance-free is safer” — no primary source for it

    ✔ The facial figures in the niacinamide study — cheek TEWL fell, but those values were not tested statistically

    ✔ Prescription drugs and procedures — they do not belong in a cosmetics piece

    ✔ An EU rule specific to sensitive skin — I did not find one, which is not the same as saying none exists

    About the author · Dr. J

    MS in Veterinary Medicine, PhD in Life Sciences. I worked as a researcher at the Korea Research Institute of Bioscience and Biotechnology (KRIBB) and now run Beaurea, a cosmetics manufacturing company, where I write the formulas myself. This blog reads the research papers and the regulatory documents and turns them into plain-language criteria for choosing ingredients. I don’t recommend specific products here – only criteria that apply to any product.

    📌 Previously

    📌 Niacinamide: How Much Is Enough — the same ingredient, seen from the brightening side

    📌 Ceramides – cholesterol and fatty acid ratio — the first ingredient here, in full

    📌 Panthenol for Skin: What the Dexpanthenol Studies Show — the irritation side

    📌 How to Read a Korean Cosmetic Ingredient List — where to find these names on the box

    📄 References

    · Regulation on Review of Functional Cosmetics, Annex 4 (Korean Law Service, opened 2026-10-17)

    · MFDS, Guideline on Test Methods for Substantiating Cosmetic Claims (2018-03, 안내서-0353-02)

    · MFDS, Guideline on Cosmetic Labelling and Advertising (2025-08-14, 안내서-0086-07), Annex 2

    · Draelos ZD, Raymond I. J Clin Aesthet Dermatol 2018;11(5):30-32

    · Biro K, Thaçi D, Ochsendorf FR, Kaufmann R, Boehncke WH. Contact Dermatitis 2003;49(2):80-84

    · Reynertson KA et al. J Drugs Dermatol 2015;14(1):43-48 · Jovanovic Z et al. ibid. 2017;16(6):605-611

    · Draelos ZD, Ertel K, Berge C. Cutis 2005;76:135-141

    · U.S. FDA, “Hypoallergenic Cosmetics” (content current as of 2022-02-25)

    · Regulation (EC) No 1223/2009, Article 14 · Regulation (EC) No 655/2013

    ――――――――――――――――――――――――――――

    This article summarises published studies and public regulatory documents. It is information, not diagnosis or treatment. Of the five studies, two had no control group and one does not report its duration, and one was run on a product containing two actives. Those limits are set out in the tables above rather than hidden. Ingredient names and concentrations are given as criteria for choosing a product, not as a recommendation of any particular one.

    — Dr. J Ingredient Notes

  • Pores and Sebum in Korean Cosmetics: Five Ingredients, and the Test Method the Regulator Wrote Down

    Cover image for an article on pore and sebum claims in Korean cosmetics. Korea's functional cosmetic notice fixes ingredients and percentages for whitening with nine entries, wrinkles with four and acne with one, and it has no pore or sebum entry at all. A separate guideline from the Ministry of Food and Drug Safety, the Guideline on Test Methods for Substantiating Cosmetic Labelling and Advertising issued in March 2018, sets out ten claim types, and chapter three is sebum secretion control. A Sebumeter tape is pressed on the skin for thirty seconds and read as sebum per unit area in micrograms per square centimetre, with casual sebum level and sebum excretion rate measured separately. Pores are not among the ten. The five ingredients chosen here are niacinamide at two percent, green tea at five percent, L-carnitine at two percent, guava leaf at six percent and salicylic acid at zero point five percent, which is the notified acne ingredient. Cover image for Dr. J Ingredient Notes.

    🇰🇷 한국어판

    Hello, this is Dr. J. Today we look at the five ingredients worth knowing for oily skin and visible pores — chosen, in every case, from a human study that actually measured sebum.

    Here is the surprise. In Korea, “pores” is not one of the claims the regulator has written a test method for. “Sebum secretion control” is — down to the instrument, the number of seconds and the unit.

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    The primary sources

    📄 MFDS, Guideline on Test Methods for Substantiating Cosmetic Labelling and Advertising (March 2018, PDF, Korean)

    📄 Green tea, split-face study (Hippokratia 2013;17(1):64-67)

    📄 L-carnitine and EGCG (J Cosmet Dermatol 2023)

    📄 Regulation (EC) No 655/2013, common criteria

    Chapter 3 of the Korean guideline sets out the sebum procedure itself — the device, the thirty seconds, the unit, and the two values that are measured separately.

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    In five lines

    ✔ Korea’s functional-cosmetic notice has no pore or sebum entry

    ✔ Yet a separate guideline sets out how sebum is measured — chapter 3 of ten

    ✔ Three ingredients here have measured sebum numbers

    ✔ One more study measured the nose and the forehead apart

    ✔ What the studies measured is sebum, not pore size

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    What Korea’s notified list does fix

    Korea’s Regulation on Functional Cosmetic Review carries an annex that fixes ingredient names and percentages. Formulate to that line and you are excused from filing fresh efficacy data — which also means the state has drawn the boundary of each claim.

    Claim What the annex fixes How to read it
    Whitening Nine ingredients with percentages (arbutin 2–5%, niacinamide 2–5%, and others) Both the name and the number are set
    Wrinkle improvement Four ingredients (retinol 2,500 IU/g, adenosine 0.04%, and others) The same
    Acne-prone skin relief One ingredient — salicylic acid 0.5% This is where blocked pores lead
    Pores and sebum No entry at all “Pore minimising” and “sebum control” have not been reviewed as claims

    That is not a ban. It means no authority has signed off on the wording. The same gap appeared in our piece on sensitive skin — but with pores and sebum there is a second document to open.

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    The claim without a method, and the claim with one

    The Ministry of Food and Drug Safety publishes a separate guidance document, the Guideline on Test Methods for Substantiating Cosmetic Labelling and Advertising (March 2018, guidance 0353-02). It gives each claim type its own chapter. There are ten.

    Chapter Claim Chapter Claim
    1 Skin moisturisation 6 Dark circle improvement
    2 Skin elasticity improvement 7 Skin blood circulation
    3 Sebum secretion control 8 Puffiness relief
    4 Temporary cellulite reduction 9 Paraben-free
    5 Suitable for acne-prone skin 10 Fine-dust protection

    Pores are not among the ten. The word appears once, in a footnote to chapter 5 that defines a comedo as a small sac formed when the opening of a sebaceous gland is blocked.

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    What chapter 3 actually says

    “A Sebumeter® is used. When the Sebumeter®, fitted with a special opaque plastic tape, is pressed on the skin with slight pressure for 30 seconds to collect sebum, the increase in the transparency of the tape is turned into a figure shown on the device, and that figure represents the amount of sebum per unit area (µg/cm²) collected.” — our translation of the Korean guideline, chapter 3

    What As the guideline sets it
    Device Sebumeter® — reads how far an opaque tape turns transparent
    Time 30 seconds of slight pressure on the skin
    Unit Sebum per unit area, µg/cm²
    Casual sebum level Measured as soon as the volunteer arrives, without washing — what has pooled on the skin
    Sebum excretion rate (SER) Measured after everyone washes with the same cleanser — how fast sebum returns
    Schedule A fixed body site, measured before and after application of the test material

    The split matters. “There is a lot of oil sitting there” and “oil comes back quickly” are different statements, and most of the studies below measured the second one.

    Evidence summary for an article on pore and sebum claims in Korean cosmetics, in five cards. First, what Korea's notified list leaves out: the functional cosmetic notice fixes ingredients and percentages for whitening with nine entries, wrinkles with four and acne with one, there is no pore or sebum entry in that table, and so pore minimising and sebum control are not claims a Korean authority has reviewed, which does not mean a brand cannot print them. Second, the test method is written down: the Ministry of Food and Drug Safety guideline on test methods for substantiating cosmetic labelling and advertising, issued March 2018 as guidance 0353-02 by the National Institute of Food and Drug Safety Evaluation, sets out ten claim types each with its own chapter, chapter three is sebum secretion control, a Sebumeter tape is pressed on the skin for thirty seconds and read as sebum per unit area in micrograms per square centimetre, casual sebum level and sebum excretion rate are measured separately, and pores are not among the ten. Third, three ingredients with sebum numbers: niacinamide two percent in Draelos 2006, where one hundred Japanese women over four weeks showed sebum excretion rate down twenty one point eight percent against ten point seven percent on placebo, while in the same paper thirty United States women over six weeks did not reach significance, so the two groups parted; green tea five percent in Mahmood 2013, where twenty two men over sixty days applied the product to one cheek against a placebo cheek and sebum was about twenty seven percent lower with a p value of zero point zero zero six zero; and L-carnitine two percent with epigallocatechin gallate five percent in Detudom 2023, where ninety subjects over four weeks showed falls in all three arms with p below zero point zero one, although there was no placebo arm. Fourth, nose and forehead measured apart: a guava leaf six percent toner in Pongsakornpaisan 2019, with twenty one subjects over twenty eight days in a split face single blind comparison against the base toner, measured with Sebutape on the forehead and on the nose, giving forehead thirteen point one zero plus or minus three point six seven percent with P below zero point zero five and nose twenty one point four three plus or minus three point two one percent with P below zero point zero zero one, parting from week three. Fifth, who writes the test method: in Korea a government guideline names ten claim types and the procedure for each, down to the thirty second reading; in the European Union, Regulation (EC) No 655/2013 says evidence shall take into account state of the art practices, and the Commission's technical document on cosmetic claims asks for methods which are reliable and reproducible while naming no particular test; in the United States the Food and Drug Administration states that it does not have a list of approved or accepted claims for cosmetics, and the same salicylic acid for acne sits at zero point five to two percent in an over the counter drug monograph. All statements come from the sources named on each card.

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    Five ingredients in one table — including where each is weak

    Ingredient Study People · duration Compared with What was measured Where it is weak
    Niacinamide 2% Draelos 2006
    J Cosmet Laser Ther 8(2)    		 100 Japanese women · 4 weeks
    30 US women · 6 weeks    		 Placebo Sebum excretion rate down 21.8% (placebo 10.7%)
    At 2 weeks 21.3% (placebo 8.6%)    		 The two groups parted — the US arm did not reach significance
    Green tea 5% Mahmood 2013
    Hippokratia 17(1)    		 22 men (22–28) · 60 days One cheek against a placebo cheek About 27% lower (p=0.0060)
    Sebumeter SM 815    		 22 men, and the raw µg/cm² values appear only in the figures
    L-carnitine 2%
    EGCG 5%    		 Detudom 2023
    J Cosmet Dermatol 22(11)    		 90 subjects, three arms · 4 weeks The three active arms against each other All three arms fell (p<0.01)
    The combination beat L-carnitine alone (p=0.009)    		 No placebo arm · age and sex are not in the abstract
    Guava leaf 6% Pongsakornpaisan 2019
    J Cosmet Dermatol 18(6)    		 21 subjects · 28 days Half the face against the base toner (single-blind) Sebutape®
    Forehead 13.10±3.67% (P<0.05) · nose 21.43±3.21% (P<0.001)
    The nose parted from week three    		 21 subjects, and the abstract alone does not settle whether the percentages are against baseline or between arms
    Salicylic acid 0.5% Korean notice, Annex 4 — — The notified ingredient for acne-prone skin relief Regulatory ground, not a sebum measurement

    Read the table across and the yardstick appears. Numbers of people, duration and comparator give the same percentage a different weight.

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    The one ingredient Korea fixed by notice

    Item As the notice sets it
    Ingredient and level Salicylic acid 0.5%
    Form Solution · lotion · cream
    Claim “Helps relieve acne-prone skin”
    Directions Apply an appropriate amount and rinse off thoroughly with water straight away
    Age restriction
    Safety standards, Annex 2    		 0.5% as salicylic acid, not for use in products for infants or products specifically labelled as usable by children aged 13 or under (shampoo excepted)

    Note the rinse-off in the directions. The form Korea reviewed is not a leave-on product. In the United States the same acid for acne is not a cosmetic ingredient at all — see the next table.

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    Who writes the test method — Korea, the EU and the US

    Korea EU United States
    List of claims For functional cosmetics the notice fixes ingredient and percentage; other claims appear on a separate substantiation list Not a list but six common criteria (Reg. (EC) No 655/2013) “FDA does not have a list of approved or accepted claims for cosmetics.“
    Test method Written out claim by claim — ten chapters, chapter 3 being sebum secretion control (Sebumeter® · 30 seconds · µg/cm²) Evidence “shall take into account state of the art practices“. The Commission’s technical document asks for “methods which are reliable and reproducible” and names no particular test No prescribed method. Labelling, including claims, “must be truthful and not misleading“
    Salicylic acid for acne A cosmetic — notified functional ingredient at 0.5% Handled inside the cosmetics regulation An OTC drug — 21 CFR 333.310 sets it at 0.5 to 2 percent
    Pores Neither in the notice nor among the ten test methods We found nothing set aside for it The same

    Put the three side by side and the axis is clear. Korea writes down what to measure and how; the EU sets a condition — reliable, reproducible, state of the art — and leaves the method to the field; the United States keeps no approved list at all. The clearest illustration is that the same salicylic acid is a cosmetic ingredient in Seoul and a drug ingredient in Washington.

    For a brand selling into Korea, that has a practical edge: the procedure your sebum claim will be read against is a public document, and it is specific enough to design a study from.

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    Four things to check on the box

    ✔ “Pore minimising” is not a reviewed claim — look for the number and the source

    ✔ What the studies measured is sebum, not pore diameter

    ✔ Check how many people and for how long — 21 and 100 are not the same weight

    ✔ Check whether there was a placebo arm — in one of these studies there was not

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    One line

    Pores have no measuring stick yet; sebum has one. Start with the side that carries numbers.

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    What I did not use, and why

    ✔ Trials that measured pore size — none of the human cosmetic studies I opened measured pores directly

    ✔ Procedures — randomised trials of botulinum toxin or microneedling for pores belong to a different article

    ✔ Retinol and pores — I opened two retinol trials; neither abstract reported a pore endpoint, and one compared against a prescription drug

    ✔ Folk claims — “pores never shrink once enlarged”, “cold water closes pores”: no primary source

    ✔ A fresh reading of the niacinamide paper — the literature databases were rate-limited on the day of writing, so the figures come from an earlier piece in which the full text was read

    About the author · Dr. J

    MS in Veterinary Medicine, PhD in Life Sciences. I worked as a researcher at the Korea Research Institute of Bioscience and Biotechnology (KRIBB) and now run Beaurea, a cosmetics manufacturing company, where I write the formulas myself. This blog reads the research papers and the regulatory documents and turns them into plain-language criteria for choosing ingredients. I don’t recommend specific products here – only criteria that apply to any product.

    📌 Related posts

    📌 Niacinamide: How Much Is Enough (Ingredient Guide 2) — the first ingredient here

    📌 Salicylic Acid (BHA): 0.5% vs 2%, Explained (Guide 8) — the notified 0.5% in full

    📌 AHA vs BHA: Is Glycolic Acid an AHA? (Guide 13) — the blocked-keratin side

    📌 How to Read a Korean Cosmetic Ingredient List (Guide 14) — finding the names on the pack

    📄 Sources

    · MFDS, Guideline on Test Methods for Substantiating Cosmetic Labelling and Advertising (civil-petition guidance 0353-02, March 2018), chapter 3

    · Regulation on Functional Cosmetic Review, Annex 4 · Regulation on Safety Standards for Cosmetics, Annex 2

    · Draelos ZD, Matsubara A, Smiles K. J Cosmet Laser Ther 2006;8(2):96-101

    · Mahmood T, Akhtar N, Moldovan C. Hippokratia 2013;17(1):64-67

    · Detudom P et al. J Cosmet Dermatol 2023;22(11):3058-3064 · Pongsakornpaisan P et al. ibid. 2019;18(6):1737-1741

    · Regulation (EC) No 655/2013, Annex (common criteria) · European Commission, Technical document on cosmetic claims

    · U.S. FDA, “Cosmetics Labeling Claims” (current as of 21 November 2022) · 21 CFR 333.310

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    This article summarises published studies and regulatory documents and is not a substitute for diagnosis or treatment. The Korean legal database was unavailable on the day of writing, so the notice figures come from earlier pieces in which the originals were read, and the niacinamide paper was not reopened. Translations of the Korean guideline are mine. Ingredient names and concentrations are given as criteria for choosing a product, not as a recommendation of any particular one.

    — Dr. J Ingredient Notes

  • Acne Skincare Ingredients: What Korea’s 0.5% Salicylic Acid Rule Means, and Four Ingredients with Human Trials

    Cover image for an article on acne skincare ingredients. It covers the one ingredient Korea's functional cosmetics notice lists for acne, salicylic acid at 0.5 percent, and four more ingredients with human trials: glycolic acid, niacinamide, tea tree oil and green tea EGCG.

    🇰🇷 한국어판: 여드름 화장품 성분 다섯 – 고시가 정한 0.5%와 사람 대상 연구 네 편

    Hello, this is Dr. J. Today we look at acne skincare ingredients — and only at what a regulation or a human trial actually says about them.

    An acne aisle in Korea will show you twenty ingredient names. Exactly one of them is listed in the country’s functional cosmetics notice for acne. For the other four in this article, I opened the trials one by one.

    This is also a good article for reading a Korean label from outside Korea, because the Korean rule and the American rule treat the same molecule in two different ways. Salicylic acid is a cosmetic ingredient here and an over-the-counter drug there, and the concentration ranges are different too. There is a table for that below.

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    📄 The sources, first

    📄 Korea — Functional Cosmetics Review notice, Annex 4 (the acne row is here)

    📄 Korea — Cosmetic Safety Standard, Annex 2 (restricted raw materials)

    📄 United States — 21 CFR 333.310, acne active ingredients

    📄 Abels 2011 — glycolic acid 10% cream, 120 people, 90 days

    📄 Draelos 2006 — niacinamide 2% and facial sebum production

    📄 Enshaieh 2007 — tea tree oil 5% gel, 60 people, 45 days

    📄 Yoon 2013 — green tea EGCG, 35 people, 8 weeks, split-face

    The two Korean annexes download as plain text from those links, with the dosage form and the wash-off instruction written out line by line.

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    In a hurry? Five lines

    ✔ Korea lists one acne ingredient: salicylic acid at 0.5%

    ✔ That product is rinsed off right after use, by the notice’s own wording

    ✔ The United States treats the same acid as an OTC drug at 0.5 to 2%

    ✔ For leave-on cosmetics, glycolic acid has a 90-day placebo-controlled trial

    ✔ Niacinamide was measured on sebum, not lesions, and two studies split

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    Five ingredients in one table, with what each was compared against

    Ingredient Source People · length Compared with What was found
    Salicylic acid 0.5%
    rinse-off    		 Korean notice, Annex 4 — Not a trial — a notice The one ingredient listed for acne-prone skin
    Glycolic acid (AHA) 10% Abels 2011 120 enrolled, 115 analysed · 90 days Placebo cream, double-blind Split from placebo from day 45; adverse events alike
    Niacinamide 2% Draelos 2006 Japan 100, 4 weeks / US 30, 6 weeks Placebo moisturizer Japan: sebum rate down 21.8% (placebo 10.7%). US: no significant difference
    Tea tree oil 5% Enshaieh 2007 60 people · 45 days Placebo gel, double-blind Total lesion count 3.55x placebo; severity index 5.75x
    Green tea EGCG 1% / 5% Yoon 2013 35 finished · 8 weeks The other half of the same face (3% ethanol vehicle) Inflammatory lesions 10.0 to 1.1 in the 1% group

    The column worth reading twice is «compared with». Two products can both say «improved» and mean very different things, depending on what sat on the other side of the comparison.

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    Korea and the United States: the same acid, two systems

    Korea United States
    What salicylic acid is for acne A functional cosmetic ingredient An OTC drug active ingredient
    Where it is written Functional Cosmetics Review notice, Annex 4 21 CFR 333.310, acne monograph
    Concentration 0.5%, one figure 0.5 to 2%, a range
    How it is used Applied, then rinsed off right away Leave-on products are covered too
    Wording on the pack 「Helps relieve acne-prone skin」 Drug Facts label, «for the treatment of acne»
    Other listed actives None for acne Benzoyl peroxide 2.5–10%, sulfur 3–10%, resorcinol 2% with sulfur

    This is the part that surprises people who read Korean labels from abroad. In Korea, a product that carries the acne functional cosmetic claim is, by the notice’s own wording, a product you wash off right away — which is why so many of them are cleansers. In the United States, the same molecule sits in 21 CFR 333.310 as an acne drug active, at 0.5 to 2 percent, and leave-on products are ordinary there.

    So «Korean acne cleanser with 0.5% salicylic acid» and «American 2% BHA leave-on» are not the same category of product wearing different labels. They are two regulatory systems that decided to file the same ingredient in different drawers.

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    What Korea’s notice actually says

    Annex 4 of the Functional Cosmetics Review notice is a list of the cases where a company does not have to submit new efficacy data. Whitening has nine ingredients on that list, wrinkle improvement has four, and acne has one:

    ✔ Ingredient and amount — salicylic acid 0.5%

    ✔ Dosage forms — solution, lotion, cream

    ✔ Claim — «helps relieve acne-prone skin»

    ✔ Directions — «take an appropriate amount, apply to the skin, then rinse off with water right away»

    There is a second Korean line worth knowing, in the Cosmetic Safety Standard, Annex 2: salicylic acid is capped at 0.5% and may not be used in products for infants, or in products labelled as suitable for children aged 13 or under — shampoos excepted. If you are buying for a younger teenager, that is the line to check.

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    A leave-on option with a trial behind it: glycolic acid 10%, 90 days

    Abels and colleagues, 2011. 120 people with mild acne (Leeds 0.25–1, mean age 21±5.8) were randomised; 115 made the final analysis. They applied a 10% glycolic acid oil-in-water emulsion once every evening for 90 days, as monotherapy, with cleansing standardised.

    The treated group separated from placebo from day 45 at the 5% significance level, and the difference held to day 90. Adverse events did not differ significantly between the groups.

    Two things are useful here. First, this is a cream you leave on, not a peel — I keep peeling and dermabrasion studies out of cosmetic articles. Second, day 45 is a reasonable answer to «how long before I judge it». Two weeks is not.

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    Niacinamide 2%: read what it actually measured

    Draelos, Matsubara and Smiles, 2006, ran two studies in two countries. In Japan, 100 women over 4 weeks: the sebum excretion rate fell 21.8% against 10.7% for placebo (at 2 weeks, 21.3% against 8.6%).

    In the United States, 30 Caucasian women over 6 weeks: casual sebum levels trended down but only reached p=0.055, and the sebum excretion rate did not reach statistical significance.

    «Niacinamide reduces oil» is repeated everywhere. The paper says two more things that rarely travel with it: it measured sebum output rather than acne lesions, and the two populations did not agree. Both belong in the sentence.

    Why not a niacinamide acne trial instead? Because most of them compare it with clindamycin gel, a prescription antibiotic. I do not line cosmetics up against prescription drugs in these articles, so I used the sebum study and said so.

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    Two with placebo-controlled trials: tea tree oil and green tea

    Tea tree: Enshaieh and colleagues, 2007. 60 people with mild to moderate acne, randomised double-blind, 30 per group, 45 days with checks every 15 days. Improvement in total lesion count was 3.55 times that of placebo, and in the acne severity index 5.75 times. Side effects were comparable and tolerable in both groups.

    Green tea: Yoon and colleagues, 2013. Thirty-seven enrolled, 35 finished 8 weeks. A randomly allocated half of each face received 1% (17 people) or 5% (18 people) EGCG solution twice daily; the other half received the vehicle, 3% ethanol only.

    In the 1% group, inflammatory lesions went from 10.0±3.1 to 1.1±0.5 and non-inflammatory lesions from 53.8±19.8 to 15.6±6.2. A split-face design removes a great deal of person-to-person noise, which is what makes a 35-person study worth reading.

    Evidence card summarizing what the sources say about five acne ingredients. First, Korea's Functional Cosmetics Review notice Annex 4 lists salicylic acid 0.5 percent as the only acne ingredient, in solution, lotion or cream form, rinsed off right after use, with the claim helps relieve acne-prone skin. Second, a glycolic acid 10 percent cream trial enrolled 120 people with mild acne, analysed 115, applied once every evening for 90 days and separated from placebo from day 45, Abels 2011. Third, a niacinamide 2 percent study measured sebum output: in Japan 100 women over 4 weeks saw the sebum rate fall 21.8 percent against 10.7 percent for placebo, while in the United States 30 women over 6 weeks showed no statistical difference, Draelos 2006. Fourth, a tea tree oil 5 percent gel trial in 60 people over 45 days improved total lesion count 3.55 times and the acne severity index 5.75 times over placebo, Enshaieh 2007. Fifth, a green tea EGCG 1 and 5 percent trial had 35 people finish 8 weeks with one half-face treated and the other half given a 3 percent ethanol vehicle, Yoon 2013.

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    How to read «it improved»

    Compared with How to read it In this article
    The same product minus the ingredient Only that ingredient is left to explain the difference — the cleanest comparison Glycolic acid, tea tree, niacinamide
    The other half of the same face Everything that differs between people is held still; the two halves can still influence each other Green tea EGCG
    The starting point (before and after) The season and the person’s routine move too, so this alone is weak Where an abstract gives no placebo figure
    A notice Not the size of an effect — the right to make a claim Salicylic acid 0.5%

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    What I left out, and why

    ✔ Trials against prescription drugs — most niacinamide acne trials compare it with clindamycin gel. A cosmetic article should not be read as putting a cream next to a prescription

    ✔ Peels and dermabrasion — salicylic and glycolic acid both have large peel literatures. That is a procedure, not a product on a shelf

    ✔ Bakuchiol — there is an acne study, but I could not confirm from the source whether it was placebo-controlled, so it waits

    ✔ Mechanism — how salicylic acid loosens keratin, or what EGCG does inside a cell, needs review articles I could not open today

    Writing down what was left out is the point of the exercise: it shows you the rule I used, so you can apply the same rule to the next ingredient someone recommends.

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    So where do you look?

    ✔ Breakouts often — start from a rinse-off product with salicylic acid 0.5%

    ✔ You want something you leave on — glycolic acid, and give it 45 days

    ✔ Oiliness is the complaint — niacinamide, knowing it was measured on sebum

    ✔ You want the gentler end — tea tree and green tea both have placebo-controlled trials

    ✔ Buying for a young teenager — check the Annex 2 age line

    ✔ Do not stack all five at once — one at a time, in the evening

    I read the claim and the trial as two separate things. A functional cosmetic claim in Korea means a listed ingredient at a listed amount; it does not tell you the size of the effect. What comes next is whether that ingredient has a human trial, and what sat on the other side of the comparison.

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    One line

    Korea lists exactly one acne ingredient — salicylic acid 0.5%, rinsed off — and the other four earn their place from placebo-controlled trials. Read the claim and the trial side by side.

    Next: five ingredients for dark spots, starting from the nine on Korea’s whitening list.

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    📌 Previously

    📌 Salicylic Acid (BHA): 0.5% vs 2%, Explained

    📌 AHA vs BHA: Is Glycolic Acid an AHA?

    📌 Niacinamide: How Much Is Enough

    📌 How to Read a Korean Cosmetic Ingredient List

    📌 Skin Concern Ingredient Map

    About the author · Dr. J

    MS in Veterinary Medicine, PhD in Life Sciences. I worked as a researcher at the Korea Research Institute of Bioscience and Biotechnology (KRIBB) and now run Beaurea, a cosmetics manufacturing company, where I write the formulas myself. This blog reads the research papers and the regulatory documents and turns them into plain-language criteria for choosing ingredients. I don’t recommend specific products here – only criteria that apply to any product.

    📄 References

    · Korea MFDS, Regulation on the Review of Functional Cosmetics, Annex 4

    · Korea MFDS, Regulation on Safety Standards for Cosmetics, Annex 2

    · 21 CFR 333.310 — Acne active ingredients (US FDA OTC monograph)

    · Abels C, Kaszuba A, Michalak I et al., J Cosmet Dermatol 2011;10(3):202-209

    · Draelos ZD, Matsubara A, Smiles K, J Cosmet Laser Ther 2006;8(2):96-101

    · Enshaieh S, Jooya A, Siadat AH et al., Indian J Dermatol Venereol Leprol 2007;73(1):22-25

    · Yoon JY, Kwon HH, Min SU et al., J Invest Dermatol 2013;133(2):429-440

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    This article summarises published regulations and research for information only; it does not replace diagnosis or treatment. If a skin problem persists, please see a professional.

    — Dr. J Ingredient Notes

  • Korea’s Nine Approved Brightening Actives: What the Human Studies Show for Melasma and Dark Spots

    Cover image for an article on the five ingredients to look for in melasma and dark spot care. Korea's functional cosmetics notification lists nine approved brightening actives with set concentrations, and this article reads the human studies for niacinamide, arbutin, magnesium ascorbyl phosphate and alpha-bisabolol, from Dr. J Ingredient Notes.

    🇰🇷 한국어판: 기미 화장품 성분 다섯 – 미백 고시 아홉 가지에서 고르는 법

    Hello, this is Dr. J. Today we are choosing brightening ingredients for melasma and dark spots the way a formulator does: from the regulation first, then from the human studies.

    Here is the part that surprises people outside Korea. In Korea, “brightening” is not a free marketing word. It is a functional claim, and there is an official list of actives with the amounts written next to them. The list has nine entries. I read the human evidence for each one, and I could open full abstracts for four. I will say that plainly as we go.

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    Primary sources

    📄 Regulation on Review of Functional Cosmetics, Annex 4 (MFDS notification) — the nine actives, their amounts, dosage forms and claim wording

    📄 Niacinamide and cutaneous pigmentation (Hakozaki 2002)

    📄 Arbutin 2.51% cream, 8 weeks (Morag 2015)

    📄 Magnesium ascorbyl phosphate and melanogenesis (Kameyama 1996)

    📄 Alpha-bisabolol in Asian women (Lee 2010)

    📄 EU SCCS opinion on alpha-arbutin and beta-arbutin (SCCS/1642/22, 31 January 2023)

    The Korean annex opens directly as an attachment file. It is worth opening once: the amounts are printed in a single line each, so you can hold the page next to a product’s back label.

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    In short, five lines

    ✔ Korea’s functional list has nine brightening actives, with the amounts fixed

    ✔ I could open full human-study abstracts for four of them

    ✔ Niacinamide separated from vehicle at 4 weeks, arbutin at 8 weeks

    ✔ The alpha-bisabolol trial was run on the back, not the face

    ✔ Tranexamic acid is not on the list, and its topical trials run 12 weeks

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    Nine actives, and what the amounts actually mean

    The annex is titled “Types of functional cosmetics for which data submission is omitted”. Read that title before you read the numbers. The concentrations are not upper safety limits. They are the amounts at which a company does not have to submit new efficacy data, because the authority has already accepted the evidence for that active at that amount.

    No. Active Amount Study opened here
    1 Broussonetia (mulberry) extract 2% —
    2 Arbutin 2–5% Morag 2015 · 102 women, 8 weeks
    3 Ethyl ascorbyl ether 1–2% —
    4 Oil-soluble licorice extract 0.05% —
    5 Ascorbyl glucoside 2% —
    6 Magnesium ascorbyl phosphate 3% Kameyama 1996 · 19 of 34
    7 Niacinamide 2–5% Hakozaki 2002 · 18 and 120 people
    8 Alpha-bisabolol 0.5% Lee 2010 · 28 women, 8 weeks
    9 Ascorbyl tetraisopalmitate 2% —

    The annex also fixes the dosage forms — lotion, liquid, cream and sheet mask — and the exact claim wording, which translates as “helps brighten the skin”. Even the directions are written down: apply an appropriate amount and spread evenly, and for a sheet mask, remove the sheet after 10 to 20 minutes and spread what is left. A product that follows all of this files a report instead of a full review.

    The five rows marked “—” are the ones where I could not open a human study abstract today. That is not the same as saying no study exists. It is a note about what I verified, and I would rather write it than leave you guessing.

    Evidence figure listing what the sources say about five brightening ingredients. First, Annex 4 of Korea's Regulation on Review of Functional Cosmetics lists nine approved actives: mulberry extract 2 percent, arbutin 2 to 5 percent, ethyl ascorbyl ether 1 to 2 percent, licorice extract 0.05 percent, ascorbyl glucoside 2 percent, magnesium ascorbyl phosphate 3 percent, niacinamide 2 to 5 percent, alpha-bisabolol 0.5 percent and ascorbyl tetraisopalmitate 2 percent, in lotion, liquid, cream and sheet mask forms. Second, the niacinamide study had 18 people use 5 percent and vehicle in a paired design and 120 tanned people use three treatments, with pigmentation falling after 4 weeks, Hakozaki 2002. Third, the arbutin 2.51 percent cream study randomised 102 women to 54 active and 48 placebo for 8 weeks, with lightening in 75.86 percent of melasma cases, Morag 2015. Fourth, magnesium ascorbyl phosphate improved 19 of 34 people with pigmentation and only 3 of 25 with normal skin, Kameyama 1996. Fifth, alpha-bisabolol was applied for 8 weeks on the back rather than the face by 28 women, Lee 2010.

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    The four, in one table — including what each was compared with

    A percentage means very little on its own. What it was measured against is where the value sits: the same cream without the active, a different product, untreated skin, or simply the starting point.

    Active Study People · duration Compared with What was found
    Niacinamide 5% Hakozaki et al. 2002 18 with hyperpigmentation vehicle moisturiser, paired on the same person Significant drop in pigmentation and rise in lightness at 4 weeks
    Niacinamide 2%
    with sunscreen    		 same paper 120 with facial tanning vehicle, sunscreen alone Better than vehicle on skin colour measures
    Arbutin 2.51% Morag et al. 2015 102 women · 8 weeks
    54 active · 48 placebo    		 placebo cream, double-blind Lightening in 75.86% of melasma, 56.00% of solar lentigo
    placebo figures not in the abstract
    Magnesium ascorbyl phosphate Kameyama et al. 1996 34 with pigmentation
    duration not in the abstract    		 baseline pigmentation 19 of 34 improved significantly · 3 of 25 with normal skin
    Alpha-bisabolol
    concentration not in the abstract    		 Lee et al. 2010 28 women · 8 weeks · back vehicle cream on the same women Significant lightening in most subjects
    Tranexamic acid
    not on the list    		 covered in guide 9 trials run 12 weeks varies by trial Topical-only results were not statistically clear

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    Niacinamide 2–5% — the point where it separated from vehicle was 4 weeks

    Hakozaki 2002 carried two human trials in one paper. In the first, 18 people with facial hyperpigmentation used a 5% niacinamide moisturiser and a vehicle moisturiser in a paired design — both products on the same face, one per side. In the second, 120 people with facial tanning were each assigned two of three treatments: vehicle, sunscreen, or 2% niacinamide plus sunscreen.

    Changes were quantified by computer analysis of high-resolution facial images and by visual grading. After 4 weeks, niacinamide significantly decreased hyperpigmentation and increased skin lightness compared with vehicle alone. The paired design is the part I like: season, sleep and sun exposure are held constant because both sides belong to the same person.

    The same paper ran cell work. Niacinamide gave 35–68% inhibition of melanosome transfer in a keratinocyte and melanocyte co-culture, and reduced pigmentation in a reconstructed epidermis model. It had no effect on mushroom tyrosinase activity or on melanin production in cultured melanocytes. Worth keeping those in their own lane: a co-culture is not a face, and I would not carry the 35–68% figure over to what happens on your cheek.

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    Arbutin 2–5% — 102 women, 8 weeks, and a different number in the EU

    Morag 2015 was a double-blind, placebo-controlled randomised trial in 102 women aged 26 to 55 with melasma or solar lentigo. Fifty-four used a cream containing 2.51% arbutin twice daily for 8 weeks; 48 used placebo.

    Lightening was seen in 75.86% of the melasma cases and 56.00% of the solar lentigo cases. The placebo-arm figures are not given in the abstract, so I have not carried them over. Read the percentage as “how many in the active arm showed lightening”, not as “how much better than placebo”.

    Europe looked at the same molecule from the safety side, which is a different question from efficacy. The SCCS adopted its opinion on 31 January 2023.

    What the number decides Korea · Annex 4 EU · SCCS/1642/22 (2023)
    Nature of the figure efficacy data can be omitted safety assessment
    Arbutin (beta) 2–5% safe in face creams up to 7%
    Alpha-arbutin not named in the annex safe in face creams up to 2%, body lotions up to 0.5%
    Hydroquinone content not the subject of this annex “as low as possible… not higher than the unavoidable traces in both arbutins”
    LOQ 3 ppm · LOD 1 ppm

    So a Korean product and a European product can both be correct and still print different percentages, because the two numbers answer different questions. And on a back label, “arbutin” and “alpha-arbutin” are two different names — the annex lists the first one. Guide 15 goes through that comparison in detail.

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    Vitamin C derivatives — 19 of 34, and only 3 of 25

    Four of the nine entries are vitamin C derivatives: ethyl ascorbyl ether 1–2%, ascorbyl glucoside 2%, magnesium ascorbyl phosphate 3% and ascorbyl tetraisopalmitate 2%. Pure ascorbic acid is unstable in a finished formula, so the molecule is modified and the skin’s enzymes are expected to release it.

    Of those four, the one I could open was magnesium ascorbyl phosphate. Kameyama 1996 reported that 19 of 34 patients with chloasma or senile freckles showed significant lightening. In the same paper, among 25 people with normal skin, only 3 did.

    Put those two numbers side by side and you get a way to read them: this is an ingredient that earns its place where the pigment already is. Expect it to work on the dark patch rather than to change your overall complexion. The trial duration is not stated in the abstract, which is worth knowing before you set a deadline for it.

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    Alpha-bisabolol 0.5% — the trial was not run on faces

    Lee 2010 tested a base cream containing alpha-bisabolol on 28 female subjects, applied once a day for 8 weeks. The application site was pigmented skin on the back, and the same women also applied a vehicle control cream. Results were assessed by clinical and biophysical methods, and after 8 weeks most subjects showed significant lightening.

    Two honest notes. The concentration of alpha-bisabolol in the cream is not given in the abstract, and the back is not the face: thicker stratum corneum, different sun exposure, different pigment history. The annex figure of 0.5% is what Korea accepted for the claim; the trial figure is simply not stated. Knowing that keeps the expectation the right size.

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    The one that is not on the list — tranexamic acid

    Tranexamic acid does not appear among the nine. A Korean product carrying the brightening claim with tranexamic acid has therefore been through an individual review with its own safety and efficacy dossier, rather than the report route that the listed actives allow.

    The trials are built around 12 weeks, and when the topical route is pooled on its own the result was not statistically clear. Guide 9 sets out those numbers, including the confidence interval, and it is the honest place to start if a tranexamic acid serum is already in your routine.

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    What is not in this article, and why

    ✔ Comparisons with hydroquinone or prescription creams — a cosmetics article should not line itself up against a drug

    ✔ Laser and chemical peel trials — procedures are a separate conversation from ingredients

    ✔ Retinol for pigmentation (Kafi 2007) — I opened the abstract and it reports fine wrinkles and collagen markers, with no pigmentation outcome, so it is out

    ✔ Mechanism paragraphs — where I could not open the review, I stopped at what the abstract itself states

    ✔ Claims that circulate online — “vitamin C erases melasma”, “use brighteners at night only” — no primary source, so no sentence

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    Four things to check when you buy

    ✔ Whether the carton carries the functional cosmetics mark, with the claim wording printed underneath in the same size or larger

    ✔ Which of the nine names appears in the ingredient list

    ✔ Whether the format is a lotion, liquid, cream or sheet mask

    ✔ Whether there is enough product for 4 to 12 weeks, since that is the length the trials ran

    Whichever active you choose, daytime sunscreen travels with it. Pigment darkens again in sunlight, and the 120-person arm of Hakozaki 2002 was itself run on top of a sunscreen. Guide 11 covers how to read SPF and PA labels.

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    One line

    Pick a name from the list of nine, give it 4 to 12 weeks, and wear sunscreen while you do.

    The next guide takes on organic and natural cosmetic labelling — what those words are allowed to certify under the Korean standard.

    📌 Related guides

    📌 Niacinamide: How Much Is Enough (Guide 2)

    📌 Arbutin vs Alpha-Arbutin: Korea’s 2–5% and the EU limits (Guide 15)

    📌 Tranexamic Acid Cream: What the Melasma Trials Found (Guide 9)

    📌 Adenosine 0.04%: Who Decided That Number (Guide 12)

    📌 How to Read a Korean Cosmetic Ingredient List (Guide 14)

    📌 Sunscreen SPF and PA: How to Read the Numbers (Guide 11)

    About the author · Dr. J

    MS in Veterinary Medicine, PhD in Life Sciences. I worked as a researcher at the Korea Research Institute of Bioscience and Biotechnology (KRIBB) and now run Beaurea, a cosmetics manufacturing company, where I write the formulas myself. This blog reads the research papers and the regulatory documents and turns them into plain-language criteria for choosing ingredients. I don’t recommend specific products here – only criteria that apply to any product.

    📄 References

    · Regulation on Review of Functional Cosmetics, Annex 4 — Types of functional cosmetics for which data submission is omitted (MFDS notification)

    · Hakozaki T, Minwalla L, Zhuang J, et al. Br J Dermatol 2002;147(1):20-31

    · Morag M, Nawrot J, Siatkowski I, et al. J Cosmet Dermatol 2015;14(3):185-190

    · Kameyama K, Sakai C, Kondoh S, et al. J Am Acad Dermatol 1996;34(1):29-33

    · Lee J, Jun H, Jung E, et al. Int J Cosmet Sci 2010;32(4):299-303

    · SCCS Opinion on alpha-Arbutin and beta-Arbutin, SCCS/1642/22, adopted 31 January 2023

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    This article summarises a public regulation and published research. It is information, not a diagnosis or a treatment plan. The figures are as written in the notification and in each abstract, and results differ from person to person. If a pigment change worries you, please speak with a professional.

    — Dr. J Ingredient Notes

  • Tranexamic Acid Cream: What the Melasma Trials Found – Alone, With Niacinamide, and Why 12 Weeks (Ingredient Guide 9)

    Cover image for Ingredient Guide 9 on tranexamic acid: a signal blocker rather than a pigment eraser, 2 to 5 percent in cosmetics, a 12-week split-face trial in 50 people with melasma and a 667-person meta-analysis. Dr. J Ingredient Notes.

    Hello, this is Dr. J.

    Ingredient Guide number nine is tranexamic acid – a name that now shows up on the back of many dark-spot and melasma products.

    Here is the surprising part. This ingredient started life as a drug that stops bleeding. This post follows how an operating-room molecule ended up in a melasma cream, and then looks at how far the topical trials actually go.

    The short version: it works on its own, but the numbers are steadier with niacinamide, and the benchmark is 12 weeks.

    🇰🇷 Read this in Korean: 트라넥삼산 크림, 기미 연구가 확인한 것 (성분 백과 ⑨)

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    📄 Read the sources first

    · Kim HJ et al., Acta Derm Venereol 2017 – meta-analysis of 11 studies, 667 participants (open access)

    · Ebrahimi B et al., J Res Med Sci 2014 – 3% cream, 50 patients, 12 weeks, split-face

    · Hsin et al., Cosmetics 2024 – 3% cream and serum, 22 patients, 8 weeks (open access)

    · Korea’s functional-cosmetic review rules – listed ingredients vs. individual review (Korean)

    · 🏠 COSMILE Europe INCI database – type the name exactly as it appears on the label

    The meta-analysis reports topical, oral and injected tranexamic acid separately. This post uses the topical numbers.

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    15-second summary · no sound

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    The four lines, if you are in a hurry

    ✔ Tranexamic acid does not erase melanin. It turns down the signal that tells skin to make more

    ✔ Cosmetics typically use 2–5%. In Korea it is not on the official whitening-ingredient list, so a “whitening” claim means the product passed an individual review

    ✔ 50 people with melasma applied a 3% cream for 12 weeks: their melasma score (MASI) fell significantly

    ✔ Across 11 studies and 667 people, topical use alone is still thinly supported – it works on its own, but the results are steadier with niacinamide

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    How it works – not an eraser, a signal blocker

    When skin is hit by UV, the surface cells (keratinocytes) use an enzyme called plasmin to send melanocytes a “make more pigment” message. Melasma is close to that message being stuck on in one patch of skin.

    ✔ Tranexamic acid blocks plasmin – the same action it has as an anti-bleeding drug

    ✔ So unlike vitamin C, which works on pigment that is already there, it slows down new pigment

    ✔ That is why results take time. Nearly every trial runs 12 weeks

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    How to read the numbers – 2%, 3%, 5% and the “whitening” claim

    The trials used 2%, 3% and 5%, and a 2024 review treats 2–5% as the usual range. On a Korean label, though, the claim tells you more than the percentage. Korea has a regulatory category called “functional cosmetics”: a product may print “whitening” only if it uses an ingredient on the MFDS list at the listed level, or passes an individual review with safety and efficacy data. Tranexamic acid is not on that list.

    What you see on the label What it means
    “Whitening functional cosmetic” claim Because tranexamic acid is not a listed ingredient, the product had to pass an individual MFDS review (safety, efficacy and human-test data) to carry this claim
    No claim · contains tranexamic acid A regular cosmetic. The ingredient is there, but the product may not say “whitening”
    Whitening claim + niacinamide, arbutin, etc. The claim may rest on a listed ingredient (niacinamide, arbutin, alpha-bisabolol, licorice extract and others) filed without review. Tranexamic acid is along for the ride
    A percentage (2% · 3% · 5%) Inside the trial range is fine. With no percentage, the position on the ingredient list is your clue – higher means more; ingredients at 1% or below may be listed in any order

    In short, a “whitening” claim means reviewed, not stronger. And no claim does not mean the ingredient is idle – for that, look at the trials below. Other countries regulate claims differently; the studies themselves are the same everywhere.

    Tranexamic acid evidence summary. 50 people with melasma applied a 3 percent cream to one side of the face for 12 weeks and the melasma score MASI fell significantly with fewer side effects than the prescription comparator, Journal of Research in Medical Sciences 2014. A meta-analysis of 11 studies and 667 people found MASI fell by 1.60 overall but only 1.36 for topical use alone, not statistically significant, Acta Dermato-Venereologica 2017. 22 people used a 3 percent cream and serum with niacinamide for 8 weeks and dark-spot color fell 13 percent, Cosmetics 2024. Tranexamic acid is not on Korea's listed whitening ingredients, so a whitening claim means an individual review.

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    What the research found – 50 people for 12 weeks, a 667-person meta-analysis, 22 people for 8 weeks

    First, 50 people with melasma. Each person applied a 3% tranexamic acid cream to one side of the face and a prescription combination to the other, for 12 weeks. Both sides improved significantly on the melasma score (MASI), with no difference between them. Side effects were significantly fewer on the tranexamic acid side (P=0.01) – Ebrahimi et al., J Res Med Sci 2014.

    Second, the 667-person meta-analysis. Pooling 11 studies, tranexamic acid overall lowered MASI by 1.60 (p<0.001). But topical use alone came to 1.36 – not quite statistically solid (p=0.08), because the individual studies disagreed with each other. Side effects were mild: redness, irritation, dryness – Kim HJ et al., Acta Derm Venereol 2017.

    Third, 22 people for 8 weeks. Adults aged 45–67 used a 3% tranexamic acid cream and serum that also contained 5% niacinamide, for 8 weeks. Dark-spot color intensity fell 13% (significant), spot size fell 6%, and 77% said their spots looked lighter. No serious adverse effects – Hsin et al., Cosmetics 2024.

    Study People · duration What was used What was found
    Ebrahimi 2014 50 · 12 weeks 3% cream alone (split-face) MASI fell significantly · fewer side effects
    Kim 2017 meta-analysis 11 studies · 667 Topical, oral and injected pooled Overall −1.60 (p<0.001) · topical alone −1.36 (p=0.08)
    Hsin 2024 22 · 8 weeks 3% + 5% niacinamide, cream and serum Spot color −13% · 77% reported lighter spots

    Put the three side by side and this is what they say. Tranexamic acid works on its own, but the studies vary enough that it is too early to call the topical evidence settled. The study that paired it with niacinamide produced steadier numbers. Using the two together is closer to what the research has seen. And every trial ran 8–12 weeks – it is not an ingredient to judge after a few days. Oral tranexamic acid and in-office procedures are outside the scope of this post.

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    How to use it – order and pairing

    ✔ Morning and night, right after cleansing, on the spots first, then moisturizer

    ✔ Niacinamide can be in the same product or the same routine – that is the pairing the trial used

    ✔ Vitamin C (the “eraser” side) fits in the same routine too – vitamin C in the morning, tranexamic acid at night is one easy split

    ✔ It is gentle enough that you rarely need to alternate days with retinol or AHAs. If that night stings, move tranexamic acid to the morning

    ✔ Sunscreen in the morning is half the job. This ingredient slows the signal; if UV keeps sending it, you stay where you started

    ✔ Oral tranexamic acid is a prescription drug. It is a separate conversation from cosmetics

    The ingredient compatibility chart shows which pairs can share a night and which should be split.

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    Five things to check before you buy

    ✔ Is the percentage printed? – 2–5% is the trial range

    ✔ Is there a “whitening” or brightening claim? – in Korea that means a review was passed. Without it, the ingredient still works

    ✔ Is niacinamide in the formula? – that is the pairing the trial used

    ✔ Where does tranexamic acid sit on the list? – higher means more

    ✔ Is there enough for 12 weeks? – this is not an ingredient to judge in under 8 weeks

    Save these five lines for the store. Reading the back takes about five minutes.

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    In one line

    🧪 Tranexamic acid slows the signal that tells skin to make pigment. It works on its own, but with niacinamide, over 12 weeks, and under sunscreen is where the research has seen it do best.

    Next in the Ingredient Guide: peptides (Guide 10) – many names, uneven evidence, so I will take them one name at a time.

    📌 Earlier posts

    · Retinol: Start at 0.1% – How to Read the Concentration Numbers (Ingredient Guide 1)

    · Skincare Ingredient Compatibility Chart – 12 Ingredients, What to Layer and What to Split

    · Dull, Rough Skin? Glycolic Acid (AHA) – What the Research Shows and How Much Is Safe

    · Salicylic Acid (BHA): 0.5% vs 2%, Explained (Ingredient Guide 8)

    About the author · Dr. J

    MS in Veterinary Medicine, PhD in Life Sciences. I worked as a researcher at the Korea Research Institute of Bioscience and Biotechnology (KRIBB) and now run Beaurea, a cosmetics manufacturing company, where I write the formulas myself. This blog reads the research papers and the regulatory documents and turns them into plain-language criteria for choosing ingredients. I don’t recommend specific products here – only criteria that apply to any product.

    📄 References

    · Kim HJ et al., Acta Derm Venereol 2017 – Efficacy and safety of tranexamic acid in melasma: a meta-analysis and systematic review (11 studies, 667 participants)

    · Ebrahimi B, Fatemi Naeini F, J Res Med Sci 2014 – Topical tranexamic acid as a promising treatment for melasma (3% cream, 50 patients, 12 weeks)

    · Hsin et al., Cosmetics 2024;11(5):168 – 3% tranexamic acid cream and serum with niacinamide, 22 patients, 8 weeks

    · Korea Cosmetics Act, Article 4 – functional-cosmetic review and listed ingredients

    This post summarizes published research and public documents for information only. It is not a substitute for diagnosis or treatment. If you have a concern, please consult a professional.

    — Dr. J Ingredient Notes

  • Ceramides Work Better With Company – What 4 Studies Say About the Back of the Jar (Ingredient Guide 4)

    Cover image for Ceramides Work Better With Company. Dr. J Ingredient Notes guide 4, summarising four studies showing that skin barrier repair was faster when ceramide, cholesterol and fatty acid were applied together.

    Hello, this is Dr. J.

    The fourth ingredient guide is about ceramides.

    Every year, as soon as the air turns dry, the same question arrives: which moisturiser should I be using?

    Here is the part that makes the answer interesting. In a 1996 experiment, skin treated with ceramides on their own repaired its barrier at a different speed from skin treated with ceramides alongside two other lipids. Same ingredient, opposite direction.

    Today I will follow that thread and end up at the back of the jar.

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    📄 Read the sources first, if you prefer

    · Man MQ et al., J Invest Dermatol 1996 – barrier repair timed as the lipid ratio was varied

    · Tanno O et al., Br J Dermatol 2000 – niacinamide and ceramide synthesis

    · 🏠 COSMILE Europe INCI database – type an ingredient name from your label and read what it is

    The abstracts carry the exact ratios and time points I have left out here. Open them above if you want them.

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    Fifteen-second summary · no sound

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    The four lines, if you are in a hurry

    ✔ Ceramides are the lipids that fill the space between skin cells. When they run low, water leaves

    ✔ Barrier repair was faster with cholesterol and fatty acid present than with ceramides alone

    ✔ In studies of 24 children and 100 adults, water loss through the skin came down

    ✔ Niacinamide raised the skin’s own ceramide production 4.1 to 5.5 fold

    ―――――――――――――――――――――

    Why ceramides alone were slower – the 1996 ratio experiment

    Picture the outer layer of skin as a brick wall. The cells are the bricks, and the mortar filling the gaps is made of three things: ceramides, cholesterol and fatty acids. Mortar only sets when all three are mixed. Pour in as much sand as you like – without cement and water it never hardens.

    Man MQ and colleagues published the experiment in the Journal of Investigative Dermatology in 1996 (volume 106, pages 1096–1101). They disrupted the barrier deliberately, applied lipids, and timed how quickly it recovered.

    ✔ One or two of the three lipids made recovery slower, not faster

    ✔ All three in equal parts restored normal speed, and a 3-fold excess of any one made it quicker still

    ✔ Confirmed in an animal model, and pointing the same way in disrupted human skin

    So a formula built around a single lipid is not the stronger formula. Which is why the useful question at the shelf is not whether a cream contains ceramides, but what the ceramides were formulated with.

    Evidence summary for ceramides. Shows that ceramide, cholesterol and fatty acid applied together restored normal barrier repair in a 1996 study, alongside a 24-child 20 to 21 week study, a 100-adult 28-day randomised controlled study, and a 2000 study in which niacinamide raised ceramide synthesis 4.1 to 5.5 fold.

    ―――――――――――――――――――――

    Did it hold up in people – 24 children, 100 adults

    Chamlin SL and colleagues, Journal of the American Academy of Dermatology 2002, volume 47, pages 198–208.

    Twenty-four children with atopic dermatitis added a ceramide-dominant product to their routine for 20 to 21 weeks. By week three, 22 of the 24 had lower severity scores, and water loss through the skin kept falling even after the scores had levelled off. The visible part settled first; the barrier itself carried on mending underneath.

    Spada F and colleagues, Dermatologic Therapy 2021, volume 34, e14970.

    One hundred adults were randomised for 28 days, one group using a ceramide-dominant cream and cleanser. Water loss and skin hydration both did better than in the control group, and ratings for itch and dryness were higher as well.

    The two products share one thing. Ceramides sat at the centre of the formula, with cholesterol and fatty acids beside them. You do not need the product names. The shape of the combination is the part worth carrying to the shop.

    ―――――――――――――――――――――

    Finding the names on the label – five lines that decide it

    Ceramides appear under several names. These are the five lines to look for.

    What you will see on the label Which of the three it belongs to
    Ceramide NP · AP · EOP · NG · AS The ceramides themselves. The letters describe structure, not grade
    Hydroxypalmitoyl sphinganine · Phytosphingosine Same family, listed under a different name
    Cholesterol The second ingredient in the 1996 experiment
    Stearic acid · Palmitic acid · Linoleic acid The fatty acid side. The third one
    Niacinamide Not a refill. It helps skin make its own

    The letters after a ceramide – NP, AP, EOP and the rest – describe molecular structure. They are not a quality ranking, and I have not found human studies comparing them head to head. Rather than picking between them, check whether cholesterol and a fatty acid are listed nearby.

    If a name is unfamiliar, type it into the COSMILE Europe INCI database and you will get its definition and function.

    ―――――――――――――――――――――

    Helping skin make its own – niacinamide

    Tanno O and colleagues, British Journal of Dermatology 2000, volume 143, pages 524–531.

    Cultured human skin cells given niacinamide for six days produced 4.1 to 5.5 times more ceramides. Fatty acids rose 2.3 fold and cholesterol 1.5 fold at the same time – all three mortar ingredients together.

    Applied to skin, it also raised ceramide and fatty acid levels in the outer layer and reduced water loss. That is the reason so many jars now carry both the refill and the prompt in one formula.

    How to read a niacinamide percentage is covered in Ingredient Guide 1, on retinol, where the same approach to concentration numbers applies.

    ―――――――――――――――――――――

    When to apply it – order and combinations

    ✔ Straight after cleansing, while skin is still slightly damp, is the easiest moment

    ✔ On retinol or AHA nights, put it on last. That is the night it earns its place

    ✔ There is no need to separate it from a vitamin C serum. Serum first, cream after

    ✔ With anything new, try it on the inner forearm and give it two days

    👉 If layering order gets confusing, the ingredient compatibility chart covers twelve ingredients and what to keep apart.

    ―――――――――――――――――――――

    Five things to check before you buy

    ✔ Are they together? Cholesterol and a fatty acid listed alongside the ceramides

    ✔ Where on the list? Ceramides near the front or middle rather than the very end

    ✔ Is niacinamide there? The refill and the prompt in one jar

    ✔ Does the texture suit your week? In dry months a cream or balm holds up better than a lotion

    ✔ Where does fragrance sit? High on the list is worth noticing when the barrier is already stressed

    Save these five lines and open them at the shelf. Reading the back of a jar takes about five minutes.

    ―――――――――――――――――――――

    In one line

    🧪 Ceramides look most like the research when cholesterol and a fatty acid are in the formula and niacinamide is nearby.

    The next ingredient guide is collagen – what changes between putting it on your skin and taking it by mouth.

    📌 Earlier posts

    · Skincare Ingredient Compatibility Chart – 12 ingredients, what to layer and what to split

    · Retinol: Start at 0.1% – how to read the concentration numbers

    · Not All Vitamin C Serums Work – 3 conditions the research says you need

    About the author · Dr. J

    MS in Veterinary Medicine, PhD in Life Sciences. I worked as a researcher at the Korea Research Institute of Bioscience and Biotechnology (KRIBB) and now run Beaurea, a cosmetics manufacturing company, where I write the formulas myself. This blog reads the research papers and the regulatory documents and turns them into plain-language criteria for choosing ingredients. I don’t recommend specific products here – only criteria that apply to any product.

    📄 References

    · Man MQ et al., J Invest Dermatol 1996;106(5):1096-1101

    · Chamlin SL et al., J Am Acad Dermatol 2002;47(2):198-208

    · Spada F et al., Dermatol Ther 2021;34(4):e14970

    · Tanno O et al., Br J Dermatol 2000;143(3):524-531

    · 🏠 COSMILE Europe INCI database

    Note: this article reads the research and sets out criteria for choosing an ingredient. It does not recommend a particular product. What suits you depends on your skin and on what you already use, so try anything new on the inner forearm first.


    Dr. J Ingredient Notes | Ingredient Guide 4 · Ceramides

  • Niacinamide: 5% Is Enough – What Each Concentration Has Actually Shown (Ingredient Encyclopedia 2)

    Niacinamide: 5% is enough - human studies ran at 2-5%, Korea's whitening functional range is 2-5%, no evidence 10% or 20% works better, Dr. J Ingredient Notes cover

    🇰🇷 이 글의 한국어판 → 한국어판

    Hello, I’m Dr. J.
    In Korea you can hardly walk past a serum shelf without seeing niacinamide on the label.
    It sits in most products approved here as brightening functional cosmetics.

    The number next to it keeps changing, though: 2%, 5%, 10%, 20%.
    Does a bigger number buy you more?
    Here is what the human studies actually support.

     

    The short version

    ✔ Niacinamide is a form of vitamin B3. One ingredient works on dark spots, pores, acne, redness, fine lines and the skin barrier
    ✔ The human studies ran at 2-5%, and Korea’s brightening functional range is also 2-5%
    ✔ No head-to-head human study shows 10% or 20% doing more. The chance of flushing does go up
    ✔ Morning and night are both fine, and it layers with retinol, vitamin C and acids
    ✔ Expect the first change around week 4 and a clear one at 8-12 weeks. Consistency matters more than strength
     

    What the research confirms – five jobs, one ingredient

    Niacinamide by concentration - 2% less sebum (Draelos 2006), 4% acne (Shalita 1995) and melasma (Navarrete-Solis 2011), 5% pigment, lines and redness (Bissett 2005, Hakozaki 2002), 10% no added benefit, 20% flushing
    · Dark spots — it blocks the hand-off of melanin to skin cells. It leaves the pigment-making enzyme alone, which is why it is gentle. Blotches faded over 8 weeks at 5%
    · Fine lines, redness, elasticity — 50 people used 5% on one half of the face and a plain cream on the other for 12 weeks. Fine lines, blotches, red spots, sallowness and elasticity all improved
    · Acne — a 4% gel matched a 1% clindamycin (antibiotic) gel over 8 weeks in 76 people
    · Sebum and pores — 2% for 4 weeks lowered sebum output. Less oil, less prominent pores
    · Barrier and dryness — it raises ceramide synthesis, so the skin loses less water. That is why it buffers a retinol or acid routine

    There is a melasma study too.
    4% niacinamide matched 4% hydroquinone with fewer side effects (27 people, 8 weeks).

     

    Choosing the number: 2, 5, 10 or 20%

    · 2% — the sebum and pore studies. A sensible starting point for sensitive skin
    · 4% — the acne and melasma studies
    · 5% — pigment, fine lines and redness. This is the reference point
    · 10% — no human comparison showing it beats 5%. More people report flushing
    · 20% — it exists on shelves, the evidence does not, and stinging is common

    That warm flush some people feel comes less from niacinamide itself than from nicotinic acid left in the raw material.
    A safety review of high-purity material (CIR) found no irritation even at 10%.
    Still, nothing shows that more is better, so 5% used for a long time is the path the research supports.

     

    Three things to check on the label

    ✔ Is there a number? “Contains niacinamide” can mean 0.5%
    ✔ A brightening functional claim (Korea) means 2-5% is definitely in there. It does not mean high strength
    ✔ If your face flushes, drop the strength or change products. Purity differs, so two 5% products can feel different
     

    When to use it, and what it layers with

    ✔ Morning and night — it is stable in light. Apply at the serum step, moisturiser on top
    ✔ With retinol → yes. It cushions the dryness and stinging of the break-in weeks
    ✔ With vitamin C → yes. The “never together” rule traces back to a 1960s solution experiment, not to modern formulas
    ✔ With AHA or BHA → yes. Applied after an acid it helps the barrier recover
    ✔ Give it 4 weeks, then keep going to 8-12 — the pigment-transfer block reverses within days of stopping, so it is an ingredient you stay on

    🧪 Check niacinamide pairings in the ingredient checker

     

    One line

    Niacinamide: 5%, morning and night, 8-12 weeks.
    It covers dark spots, pores, redness and the barrier at once and gets along with everything else, which makes it a good default serum in a routine.

    ▶ Ingredient encyclopedia 1: Retinol: Start at 0.1% – How to Read the Concentration Numbers
    ▶ Ingredient encyclopedia 3: Bakuchiol vs Retinol – What a 44-Person Trial Found
    ▶ Earlier post: Skincare Ingredient Compatibility Chart – What to Layer and What to Split
    ▶ Earlier post: Not All Vitamin C Serums Work – 3 Conditions the Research Says You Need
    🇰🇷 이 글의 한국어판 → 한국어판

    About the author · Dr. J
    MS in Veterinary Medicine, PhD in Life Sciences. I worked as a researcher at the Korea Research Institute of Bioscience and Biotechnology (KRIBB) and now run Beaurea, a cosmetics manufacturing company, where I write the formulas myself. This blog reads the research papers and the regulatory documents and turns them into plain-language criteria for choosing ingredients. I don’t recommend specific products here – only criteria that apply to any product.

    References
    1. Korea MFDS, Regulation on the Review of Functional Cosmetics, Table 4 — brightening: niacinamide 2-5%
    2. Bissett DL et al. Dermatologic Surgery 2005;31:860-865 — 5%, 50 subjects, 12 weeks, split-face
    3. Hakozaki T et al. British Journal of Dermatology 2002;147:20-31 — melanosome transfer reduced 35-68%, 5% for 8 weeks
    4. Shalita AR et al. International Journal of Dermatology 1995;34:434-437 — 4% vs 1% clindamycin, 76 subjects, 8 weeks
    5. Draelos ZD et al. Journal of Cosmetic and Laser Therapy 2006;8:96-101 — 2%, sebum output
    6. Navarrete-Solís J et al. Dermatology Research and Practice 2011 — 4% vs 4% hydroquinone, 27 subjects, 8 weeks
    7. Tanno O et al. British Journal of Dermatology 2000;143:524-531 — ceramide and barrier lipid synthesis

    ※ This article is general information. Results vary with individual skin. It does not recommend or criticise any specific product. If you are being treated for a skin condition, talk to your dermatologist first. The author runs a company that manufactures and sells cosmetics.