Tag: salicylic acid

Exfoliating Actives in Korea: No Claim Category, but a Label Rule

Hello, this is Dr. J. Today we are looking at exfoliating actives in Korean cosmetics, and at what the studies behind them actually measured.

Here is the part most guides skip. Exfoliation is not a reviewed claim in Korea. It is not one of the six notified categories, and it is not one of the ten official test methods. Yet the label rules name it anyway.

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The primary documents

📄 Regulation on the Examination of Functional Cosmetics, Annex 4

📄 Regulation on Safety Standards for Cosmetics, Annex 2

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

📄 U.S. FDA, Alpha Hydroxy Acids

📄 Stiller MJ et al., Arch Dermatol 1996 (22 weeks, 74 women)

Annex 4 names six categories; the guideline names ten test methods. Exfoliation is in neither.

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The short version

✔ Korea notifies actives in six categories, and exfoliation is not one of them
✔ The regulator’s ten test methods do not cover it either
✔ Above 0.5% AHA a sun sensitivity warning becomes mandatory on the box
✔ Even a 10-50 mL package that shortens its ingredient list cannot drop fruit acid (AHA)
✔ So the useful question is what each study measured

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1. Korea notifies actives by claim, and exfoliation is missing

Korea runs functional cosmetics as a positive list. For each claim the notification names the ingredient and the percentage, and it also fixes the dosage form and the wording a company may print.

Category	What the notification sets	How to read it
UV protection and tanning	27 ingredients with maximum levels	Both the name and the number are 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	Dye lists split across six tables	Same
Hair removal	Thioglycolic acid 3.0-4.5%, pH 7.0 to below 12.7	A single ingredient
Acne-prone skin relief	Salicylic acid 0.5%, in cleansing products of soap composition	One of today’s five sits here
Exfoliation	There is no category	So there is nothing to be reviewed for

The last row is the point of this article. There is no exfoliation category, so there is nothing for a company to be reviewed against, and no notified percentage to compare a product with.

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2. There is no test method for it either

Separately from the notification, the Ministry publishes a guideline that sets out how to measure each claim: who the subjects are, which instrument is used, and what counts as a result. It has grown one claim at a time.

Chapter	Claim	Added
1	Skin hydration	2012, at the start
2	Skin elasticity	2012, at the start
3	Sebum control	2012, at the start
4	Temporary reduction of cellulite	2013
5	Suitable for acne-prone skin	2013
6	Dark circles	2014
7	Skin microcirculation	2015
8	Puffiness	2015
9	Paraben-free	31 March 2017
10	Fine dust protection	28 March 2018
—	Exfoliation	Never added

Ten chapters, added over six years, and exfoliation never arrived. In our earlier pieces the pattern was different each time: for sensitive skin the phrase appeared only as a subject exclusion criterion, and for sebum there was a full chapter with a Sebumeter procedure. Exfoliation is the third case — absent from both documents.

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3. The label rules name it even so

A claim category is one instrument. A label rule is another, and Korea uses the second here. Once a product passes 0.5% AHA, a notification requires fixed sentences on the box.

When it applies	What the box has to say
AHA above 0.5%	The product may increase the skin’s sensitivity to sunlight, so use a sunscreen alongside it (rinse-off and hair products are excepted).
Same threshold	Test it on a small area first and check for a skin reaction.
AHA above 10%, or pH below 3.5	The product contains a high concentration of AHA and may cause adverse effects, so consult a physician.

So the sunscreen sentence you find on the back of a Korean exfoliating toner is not marketing. It is text a notification requires, and its trigger is a concentration.

The second place is the ingredient list. Small containers may shorten it, but six things stay.

Enforcement Rule of the Cosmetics Act, Article 19(2)3 — what a small package may not drop

A package holding more than 10 mL and up to 50 mL (or more than 10 g and up to 50 g) may omit ingredient labelling, except for:
(a) tar colourants · (b) gold leaf · (c) the type of phosphate in shampoos and rinses
(d) fruit acid (AHA) · (e) ingredients that produce the effect of a functional cosmetic · (f) ingredients for which the Minister has notified a blending limit
※ Where labelling is omitted, the company must let consumers check the full list by telephone or website, or keep a printed list at the point of sale (paragraph 5).

An active with no claim category of its own is still named in the labelling rules. That is the shape of this subject in Korea.

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4. Roughness: the two AHAs did not behave the same

The cleanest cosmetic-strength trial here is old and still useful. 74 women aged 40 to 70, 22 weeks, randomised, double blind and vehicle controlled, applying 8% glycolic acid or 8% L-lactic acid twice a day to the face and outer forearms.

On the face, at least one grade of improvement was reached by 76% on glycolic acid, 71% on lactic acid and 40% on the vehicle.

On the forearm the two parted company. Lactic acid beat the vehicle for roughness; glycolic acid beat it for overall photodamage and sallowness but not for roughness. If you have read that the AHAs are interchangeable, this is the trial that complicates it.

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5. Horny layer thickness: urea

A separate study compared urea 2% cream, 10% cream and 10% foam against petrolatum and untreated skin, in healthy volunteers and in people with type I and type II diabetes.

The 10% cream slightly lowered transepidermal water loss and reduced horny layer thickness, with no excessive occlusion from any of the products.

Korea’s safety standards set the ceiling for urea at 10%, so the concentration the study used sits at the regulatory limit rather than below it.

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6. The one Korea notifies: salicylic acid 0.5%

Regulation on the Examination of Functional Cosmetics, Annex 4 — acne-prone skin relief

Ingredient and level: salicylic acid 0.5% · Product type: cleansing products of soap composition · Forms: solution, lotion, cream
Claim: “helps relieve acne-prone skin”
Directions: apply an appropriate amount to the skin and rinse off immediately with water

The directions matter as much as the percentage. What the notification covers is a rinse-off cleanser, not a leave-on treatment.

The safety standards then split the ceiling three ways: 0.5% when used as a preservative, 2% in personal cleansing products, and 3% in rinse-off hair products — the latter two only where it is the active of a functional cosmetic.

One more line sits with it: salicylic acid may not be used in products for infants, or in products labelled for children aged 13 or under, with shampoo excepted.

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7. Irritation: PHA (lactobionic acid)

Lactobionic acid at 10% was held under a 24 hour occlusive patch in 10 volunteers, with transepidermal water loss, erythema and stratum corneum hydration read afterwards. No irritation appeared.

The hydration arm of the same paper ran in 16 volunteers over 3 hours and 21 days, and there the authors are direct: a statistically significant difference between the placebo and the sample with lactobionic acid was not observed.

Read together, PHA is an ingredient with mildness shown rather than strength shown. That is worth separating when a product page offers it as a gentler route to the same result.

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The five side by side

Ingredient	People	Duration	Design	Measured	Result
Glycolic acid 8%	74, shared	22 weeks	Randomised, double blind, vehicle controlled	Facial grade, forearm roughness	Face 76% vs vehicle 40%; no difference in roughness
Lactic acid 8%	74, shared	22 weeks	Same trial	Facial grade, forearm roughness	Face 71%; roughness also beat vehicle
Urea 10%	not in abstract	not in abstract	Compared with petrolatum and untreated skin	Water loss, horny layer thickness	Horny layer thickness fell
Lactobionic acid 10%	10 and 16	24 h and 21 days	Patch test and hydration arm	Irritation, hydration	No irritation; hydration no different from placebo
Salicylic acid 0.5%	—	—	Notified active	—	Acne-prone skin relief

The endpoints are not interchangeable. Roughness, horny layer thickness and irritation are three different measurements, and a product page that says “clinically proven” rarely says which one it means.

And where each study is weak

Study	Where it is weak, stated plainly
Stiller 1996	The facial endpoint is an investigator grade, and roughness was read on the forearm. One participant withdrew for irritation and six for personal reasons.
Borelli 2011	The abstract gives neither the number of participants nor the overall duration. Healthy volunteers and diabetic patients were studied together.
Tasic-Kostov 2011	Hydration showed no significant difference from placebo. The irritation arm is a single 24 hour patch in 10 people.
Salicylic acid	No human trial is attached here — only the level and the directions the notification sets.

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8. Korea, the United States and the EU — the same two numbers, different force

No regulator here keeps a claim list for exfoliation. What differs is which instrument fills the gap.

	Korea	United States	European Union
Claim-based ingredient list	Six categories; exfoliation is not one	None — “FDA does not have a list of approved or accepted claims for cosmetics”	Permitted lists cover colourants, preservatives and UV filters (Art. 14)
Test procedure	Ten chapters; exfoliation is not one	Not written down	655/2013 requires “state of the art practices”
AHA and sunlight	Mandatory label text by notification, above 0.5%	Recommended Sunburn Alert, in a guidance	No entry found for this
The same two numbers	Above 10%, or pH below 3.5, adds a line	CIR found 10% or less and pH 3.5 or greater safe	—
Force of the document	Omitting the text is a labelling breach	“do not establish legally enforceable responsibilities”	Common criteria bind; the method is a condition

The striking part is the arithmetic. Korea’s notification adds the physician line above 10% AHA or below pH 3.5. In the United States, the Cosmetic Ingredient Review panel concluded that glycolic and lactic acid are safe where the concentration is 10 percent or less and the final product has a pH of 3.5 or greater. The same two numbers, drawn from the opposite side.

What separates them is the document. Korea’s sits in a notification, so leaving the sentence off the box is a labelling breach. The United States puts its Sunburn Alert wording in a guidance issued in January 2005, and FDA states plainly that its guidances “do not establish legally enforceable responsibilities” and “should be viewed only as recommendations”.

The EU does not run a claim-based ingredient list at all. Article 14 of Regulation (EC) No 1223/2009 keeps positive lists for colourants, preservatives and UV filters, and claims are governed instead by Regulation (EU) No 655/2013: they “shall be supported by adequate and verifiable evidence”, and that evidence “shall take into account state of the art practices”.

For anyone exporting into Korea, the practical reading is short: there is no exfoliation dossier to file, and the compliance work sits on the label instead.

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What to check on the box

✔ Ask what was measured — roughness, horny layer thickness or hydration
✔ A sun sensitivity sentence on the box means the product is above 0.5% AHA
✔ For salicylic acid, the ceiling depends on whether the product is rinsed off
✔ Even a small container lists fruit acid (AHA)

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One line

Exfoliation is not a reviewed claim in Korea; it is a labelled one. Decide which endpoint matters to you — roughness, horny layer thickness or mildness — and the list of five becomes a list of two.

Next: five actives for skin elasticity — chapter 2 of the same guideline, and unlike exfoliation, a claim with a written test procedure.

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What is not in this article, and why

✔ Peel and chemical resurfacing trials — those are procedures, not cosmetics. Only leave-on cosmetic strengths of 8 to 10% were used here
✔ A urea dose-ranging study (Addor et al., Surg Cosmet Dermatol) — the journal page carries no publication year, volume or pages, so it could not be cited properly
✔ A gluconolactone study (PMID 33769633) — Europe PMC returned 429 and PubMed a reCAPTCHA
✔ Enzyme and physical scrubs — no human study was found
✔ Whether Annex III of Regulation 1223/2009 carries entries for glycolic or lactic acid — the annex table could not be opened, so this is recorded as not found rather than as absent

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

📌 Acne Skincare Ingredients and Korea’s 0.5% Salicylic Acid Rule — the same salicylic acid entry, read from the acne side

📌 Pores and Sebum: the Test Method the Regulator Wrote Down — the mirror image of today’s piece

📌 Is Glycolic Acid an AHA? AHA vs BHA, Explained — the two acids in today’s trial

📌 Salicylic Acid (BHA): 0.5% vs 2%, Explained — why the ceiling splits

📄 Sources

· Regulation on the Examination of Functional Cosmetics, Annex 4 (Korea Law Information Center, accessed 20 October 2026)

· Regulation on Safety Standards for Cosmetics, Annex 2 (same, accessed 20 October 2026)

· MFDS, Guideline on Test Methods for Substantiating Cosmetic Labelling and Advertising Claims (March 2018, no. 0353-02)

· Notification on Cautions in Use and Labelling of Fragrance Allergens in Cosmetics (cross-checked on the Korea Cosmetic Association ingredient dictionary)

· Enforcement Rule of the Cosmetics Act, Article 19 (Korea Cosmetic Association, statute page)

· Stiller MJ, Bartolone J, Stern R, Smith S, Kollias N, Gillies R, Drake LA. Arch Dermatol 1996;132(6):631-636

· Borelli C, Bielfeldt S, Borelli S, Schaller M, Korting HC. Int J Cosmet Sci 2011;33(1):37-43

· Tasic-Kostov MZ, Reichl S, Lukic MZ, Jaksic IN, Savic SD. Pharmazie 2011;66:862-870

· U.S. FDA, “Alpha Hydroxy Acids”; “Guidance for Industry: Labeling for Cosmetics Containing Alpha Hydroxy Acids” (January 2005); “Cosmetics Labeling Claims”

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

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This article summarises published studies and public regulatory documents; it is not medical advice. The Korean notifications and annexes were opened in the original on the day of writing, and the AHA warning wording was taken from two Korea Cosmetic Association ingredient pages that matched word for word, because the notification annex PDF could not be opened. Of the studies cited, one does not report its participant count and one endpoint showed no difference from placebo; both are stated in the tables. Ingredient names and percentages are given as criteria for choosing a product, not as a recommendation of any particular one.

— Dr. J Ingredient Notes

October 20, 2026

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

🇰🇷 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.

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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

📌 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

October 16, 2026

Children’s Cosmetics in Korea: What the Label Triggers, and Why the Box Prints a Preservative Percentage (Ingredient Guide 20)

Cover image for a guide to Korea's rules for children's cosmetics, Ingredient Guide 20 from Dr. J Ingredient Notes. Infants are three years of age and under and children are four to thirteen, and once a product says so on the label three rules follow.

🇰🇷 한국어판: 어린이 화장품 기준 – 「어린이용」이라 적으면 따라오는 것, 그리고 상자의 보존제 함량

Hello, this is Dr. J. Today I want to read Korea’s rules for children’s cosmetics straight from the statute, because one of them changes what is printed on the box.

Most countries regulate what may go into a product for a child. Korea does that too, but it adds something unusual: once a product says it is for children, the outer package has to carry the amount of preservative in it, as a number, separate from the ingredient list. I have not found that requirement anywhere else.

And the trigger is not the formula. It is the label. That is the part worth understanding first, so let me start there.

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The sources, if you would rather read them first

📄 Korea Ministry of Government Legislation — cosmetics for infants and children — the age brackets and the three documents

📄 Safety Standards for Cosmetics, Annex 2 — the entries that carry an age condition

📄 Commission Regulation (EU) No 1004/2014 — parabens and the nappy area

📄 US FDA — Summary of Cosmetics Labeling Requirements — what a US label has to carry

The Korean annexes open as attachment files, so the text comes up directly rather than through a search form.

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Five lines, if you are in a hurry

✔ Korean law splits the two groups by age — an infant is 3 and under, a child is 4 to 13

✔ The rules attach the moment the package, the product name or an advertisement says the product is for them

✔ Three safety documents must be written and kept, for a year past the expiry date or three years past the manufacturing date

✔ The outer package gains one line — the content of the preservatives, printed apart from the ingredient list

✔ Salicylic acid and iodopropynyl butylcarbamate step out of products labelled for under-13s

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Two age groups, written into the statute

Article 4-2 of the Cosmetics Act and Article 10-2 of its Enforcement Rule define the two groups by age. An infant is three years of age and under. A child is four to thirteen.

The upper bound is worth noticing. Thirteen takes in primary-school age, so a lotion or a lip balm marketed to a nine-year-old sits inside the same rules as a baby lotion. In several other markets the special category stops at three.

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The rule starts at the label, not at the formula

This is the part that surprises people. The obligations do not attach because of what is in the bottle. They attach because of what the company says about who it is for.

Where	What makes the rules attach
Packaging	The inner or outer package states, specifically, that the product may be used by an infant or a child
Product name	The name of the cosmetic itself carries a reference to infants or children — the name alone is enough
Advertising	Newspapers, broadcast, magazines, the internet, posters and signboards, video or film, stating it specifically

So a very mild formula with no such wording stays outside the rules, and an ordinary formula with the wording falls inside them. The word the statute uses is “specifically”: a vague impression that a child might use it is not the test — naming the group is.

※ This is why the phrase on the front of a Korean box is a regulatory statement rather than a marketing flourish.

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Three documents, and how long they are kept

Once that wording is used, the responsible distributor has to prepare and keep product-specific safety documentation. Enforcement Rule Article 10-3 lists three items and sets the retention period.

Document	Content	Kept until
① Product and method	A description of the product and of how it is manufactured	Products labelled with an expiry date — one year after the expiry date of the last batch made or imported Products labelled with a period after opening — three years after the manufacturing date of the last batch
② Safety assessment	A safety assessment of the cosmetic product
③ Evidence of effect	Evidence for the efficacy or effect claimed for the product

The retention clock keeps running after the product has left the shelves — a year past the expiry date of the final batch. Failure to prepare or keep the documents carries up to one year of imprisonment or a fine of up to ten million won, and a company can be fined alongside the individual.

※ A shopper cannot ask to see this file. What is useful to know is that the phrase “for children” on a Korean box has a dossier sitting behind it.

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One extra line on the box — the preservative content

Here is the part a shopper can actually see. Where a product is labelled or advertised specifically for infants or children, the outer package must carry “the content of preservatives among the raw materials whose standards of use are designated and published”.

Compare that with the ordinary ingredient list. Ingredients are listed in order of how much is present, and in Korea anything at or below 1% may be listed in any order. No amounts appear. On a children’s product, the preservatives come back with a number attached — “phenoxyethanol 0.4%”, printed in its own line.

Two things follow from that line. First, its presence tells you the product is formally labelled for children. Second, it tells you which preservative is in there and how much. If no preservative is used, there is nothing to declare and the line is simply absent.

※ The basis is Article 10 of the Act with Article 19 of the Enforcement Rule. Look for it beside the ingredient list, not inside it.

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Two ingredients that step out

Annex 2 of the Safety Standards for Cosmetics sets a maximum for each restricted raw material. Two of those entries carry an age condition, and I opened both.

Ingredient	Limit	Age condition
Salicylic acid and its salts	0.5% as salicylic acid	Not to be used in products for infants, or in products labelled specifically as usable by children aged 13 or under (shampoo excepted)
Iodopropynyl butylcarbamate (IPBC)	0.02% rinse-off · 0.01% leave-on · 0.0075% in deodorants	The same prohibition (bath products, shower gels and shampoos excepted)

Read the two columns together. 0.5% is the adult ceiling; in a children’s product the ingredient is not permitted at all, not permitted at a lower level. The exceptions in brackets follow the same logic in reverse — products that are rinsed off are treated differently from products that stay on the skin.

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Fragrance allergens: 25 names, the same thresholds

If a Korean ingredient list ends with limonene, linalool, citronellol and a few more, those are the fragrance allergens that must be named separately rather than hidden inside “fragrance”. There are 25 of them.

The thresholds are above 0.01% in rinse-off products and above 0.001% in leave-on products. They are not lowered for children’s products — the annex carries no age clause at all.

※ A long tail of names is disclosure, not concealment. For a child who reacts to fragrance, that tail is the part of the label worth reading.

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Korea, the EU and the US, side by side

Three regulators, three different places to put the line. Korea hangs its rules on the label, the EU writes age into individual ingredient entries, and the US asks for no amounts on the label at all.

Where	What applies to a children’s product	Source
Korea	Infant 3 and under, child 4 to 13. Label or advertise it as such and three safety documents follow, plus the preservative content printed on the package	Cosmetics Act Art. 4-2, Art. 10 Enforcement Rule Art. 10-2, 10-3, 19
European Union	Propylparaben and butylparaben capped at 0.14% as the sum (as acid), and “not to be used in leave-on products designed for application on the nappy area of children under three years of age”; such products carry “Do not use on the nappy area”	Reg. (EU) No 1004/2014 Annex V entry 12a, applying from 16 April 2015
United States	“The ingredients must be declared in descending order of predominance”, and “color additives and ingredients present at one percent or less may be declared without regard for predominance”. No amount has to be shown	US FDA, Summary of Cosmetics Labeling Requirements

The contrast worth taking away is the middle column of the first row. A Korean children’s box tells you how much preservative is in the product. A European or American one does not, however carefully it is labelled otherwise.

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What to check on the box

✔ Does the package say, in so many words, that it is for children? That is what puts it inside these rules

✔ Is there a preservative line separate from the ingredient list, and which preservative is named

✔ If salicylic acid appears, is the product one that gets rinsed off

✔ For a child who reacts to scent, read the names after “fragrance”

✔ Is the expiry date on the container itself, which survives after the box is thrown away

※ A printed line is easier to verify than a claim such as “no preservatives”. Choose on what is written.

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What I left out, and why

✔ Whether Korea restricts parabens by age. The EU does. In the extract of Annex 2 I was able to open, the paraben entries carried no age condition — but I could not confirm the full entry, so I am not claiming Korea has no such rule

✔ The sub-paragraph numbers for the preservative-content requirement. Different official sources number it differently, so I cite the Act’s Article 10 with Article 19 of the Enforcement Rule and stop there

✔ “Baby products should be fragrance-free and preservative-free.” There is no primary source for that as a rule, and removing preservatives moves the microbiological question elsewhere rather than removing it

✔ Product names. This blog does not recommend particular products

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In one line

In Korea, the rules for a children’s cosmetic begin with the words on the label, not with the formula inside. Say it, and a dossier follows — and the box gains a line telling you how much preservative is in there.

Next in this series: what a “vegan” claim on a cosmetic certifies, which in Korea runs through an industry self-review rather than a government mark — a companion to the organic and natural guide (Ingredient Guide 21).

📌 Earlier guides

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

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

📌 Ceramides: the Cholesterol and Fatty Acid Ratio (Guide 4)

📌 Niacinamide: How Much Is Enough (Guide 2)

About the author · Dr. J

📄 References

· Cosmetics Act of Korea, Articles 4-2 and 10

· Enforcement Rule of the Cosmetics Act, Articles 10-2, 10-3 and 19

· Safety Standards for Cosmetics, Annex 2 (restricted raw materials)

· Notification on precautions and fragrance allergen labelling, Annex 2 (25 substances)

· Commission Regulation (EU) No 1004/2014, Annex Ⅴ entry 12a

· U.S. FDA, Summary of Cosmetics Labeling Requirements

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This article summarises public statutes and regulatory documents and is not a substitute for diagnosis or treatment. Quoted sentences are as they appear in the law and the notifications, and labelling practice varies between products. If a child’s skin reacts, stop using the product and speak to a professional.

— Dr. J Ingredient Notes

October 1, 2026

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.

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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

📄 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

September 29, 2026

AHA vs BHA: Is Glycolic Acid an AHA? — Water vs Oil, What Korea Caps, and Why the Same Acid Is a Drug in the US (Ingredient Guide 13)

Cover image for a Dr. J Ingredient Notes guide on AHA versus BHA, ingredient guide 13. Glycolic acid is an alpha hydroxy acid that dissolves in water and works on surface keratin, salicylic acid is a beta hydroxy acid that dissolves in oil and mixes with sebum inside the pore, and Korea and the United States regulate the two in different ways.

🇰🇷 한국어판: AHA BHA 차이 – 글리콜산과 살리실산 (성분 백과 ⑬)

Hello, I’m Dr. J. Short answer first, because it is the question people actually type: yes, glycolic acid is an AHA — an alpha hydroxy acid, and the smallest of them. Salicylic acid is the BHA. This is Ingredient Guide 13.

The long answer is more useful. One of the two dissolves in water and one in oil, and that single property decides where each ends up on your face. It also explains something stranger: Korea and the United States regulate these two acids in almost opposite ways, and the same salicylic acid that sits in a Korean cosmetic is an over-the-counter drug in the US.

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📄 If you’d rather read the primary sources

📄 Korea — Enforcement Rule of the Cosmetics Act, Annex 3: precautions for AHA products (Korean)

📄 Korea — Regulation on Cosmetic Safety Standards, Annex 2: restricted ingredients (Korean)

📄 US — 21 CFR 333.310, active ingredients for topical acne drug products (eCFR)

📄 US FDA — Alpha Hydroxy Acids: the UV-sensitivity study and the Sunburn Alert wording

🏠 Korean Cosmetic Association ingredient dictionary — paste a name from your label

The two Korean annexes are the ones nobody quotes. Annex 3 holds the AHA labelling lines; Annex 2 holds the salicylic acid caps.

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In four lines, if you’re in a hurry

● Glycolic acid is an AHA and dissolves in water. Salicylic acid is the BHA and dissolves in oil

● So AHA works on surface keratin; BHA mixes with sebum and reaches inside the pore

● Korea caps salicylic acid — 0.5%, 2% or 3% depending on what the product is

● Korea does not cap AHA. It requires label lines instead, above 0.5% and again above 10%

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Is glycolic acid an AHA? Yes — and here is what that means

AHA stands for alpha hydroxy acid, and it is a family rather than one ingredient. Glycolic acid is the best known member; lactic acid and mandelic acid are AHAs too. So “AHA” and “glycolic acid” are not two competing things — one contains the other. When a label says only “contains AHA”, the useful move is to find the actual name further down the ingredient list.

BHA stands for beta hydroxy acid, and in skincare it effectively means salicylic acid. The alpha and the beta refer to where a hydroxyl group sits on the molecule, which sounds academic until you see what it does: it changes what the acid dissolves in.

A 2015 review states the difference plainly: salicylic acid is a lipid-soluble agent, in contrast with the alpha hydroxy acids, and it is miscible with the lipids of the sebaceous glands in hair follicles. Sebum is oil. So salicylic acid travels with it, into the pore. Glycolic acid, being on the water side, stays and works at the surface.

	AHA	BHA
Members you’ll see	glycolic acid · lactic acid · mandelic acid	salicylic acid
Dissolves in	water	oil
Where it acts	surface keratin	mixes with sebum, inside the pore
Korea regulates by	no cap · mandatory label lines	a cap on the amount
Daytime	pair with sunscreen — the rule says so on the label	no such required line

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Korea ① — salicylic acid is capped by amount

Korea keeps a list called Annex 2, ingredients requiring restrictions on use. Salicylic acid is on it, and the limit is not a single number — it changes with what the ingredient is doing in the formula.

Used as	Limit	Product type
Preservative	0.5%	listed in the preservatives table
Functional-cosmetic active	2%	body-cleansing products
Functional-cosmetic active	3%	rinse-off hair products

The notes beside the numbers matter as much as the numbers. Salicylic acid may be used only as a functional-cosmetic active, not in other product types. It is also barred from products for infants, or from anything labelled as suitable for children aged 13 and under, with shampoo excepted. So when you read a percentage, read the product category next to it.

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Korea ② — AHA is not capped. It is labelled

AHA gets the opposite treatment. Instead of limiting how much may go in, Korea’s Enforcement Rule specifies what the label has to say. Item 11 of Annex 3 applies to any product above 0.5% AHA.

Trigger	Required line	Exempt
above 0.5%	use a sunscreen alongside this product	rinse-off and hair products
above 0.5%	patch-test on a small area first	—
above 10% or pH below 3.5	consult a specialist	—

This gives a Korean label a property that is quietly useful: the consult-a-specialist line is a concentration signal. A brand does not have to print the percentage, but if that sentence is there, the product is either above 10% or below pH 3.5. If it is absent, the product sits under both thresholds. The label tells you what the marketing does not.

And the sunscreen line is not decorative. The FDA’s own testing found that after four weeks of AHA use, sensitivity to UV-induced redness rose by 18%. Korea wrote the warning into a rule; the US described the same finding and recommended wording. Same evidence, two different instruments.

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In the US, one of these is not a cosmetic at all

Here is the part that surprises people who shop across both markets. In the United States, salicylic acid for acne is not regulated as a cosmetic — it is an over-the-counter drug. The monograph at 21 CFR 333.310 lists the permitted acne actives, and one line reads exactly: “Salicylic acid, 0.5 to 2 percent.“

AHA runs the other way. The US sets no concentration limit for it in cosmetics. The industry’s Cosmetic Ingredient Review panel concluded AHA products are safe when the concentration is 10% or less and the finished product has a pH of 3.5 or greater — the same two numbers Korea uses, but as a panel conclusion rather than a rule. And the Sunburn Alert sentence comes from a 2005 guidance, which is a recommendation, not a binding requirement.

Question	Korea	United States
Salicylic acid for acne is…	a functional cosmetic, capped at 2% in cleansers	an OTC drug, 0.5 to 2% under the monograph
AHA concentration limit	none — labelling instead	none — CIR advises 10% or less, pH 3.5 or above
AHA sun warning	mandatory, written into the Enforcement Rule	non-binding guidance (2005 Sunburn Alert wording)
Checked before launch	reviewed or reported to the MFDS	cosmetics need no FDA approval

Neither arrangement is strictly better, and that is not the point. The practical consequence is narrower: a product bought outside Korea does not carry the Korean label lines, so the concentration signal described above simply is not there. On an imported bottle you are back to reading the brand’s own claims.

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Which one do you need?

If this is the concern	Look at	On the label
Rough, dull surface	AHA	where glycolic or lactic acid sits, and whether the sunscreen line is there
Pores and sebum	BHA	salicylic acid, and whether it’s a cleanser or a hair product
First time with acids	the lower end	a product with no consult line sits under both thresholds
You want both	split them	different times of day rather than layered on the same spot

If you use an AHA, pair it with sunscreen in the daytime. That is the one instruction both regulators agree on, and how much sunscreen actually counts is covered in the SPF and PA guide.

※ One thing I could not confirm: how far an ordinary Korean cosmetic may go in advertising “exfoliation” wording. I could not obtain the MFDS notice text. If I get it, I’ll add it here.

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In one line

Water-soluble means surface; oil-soluble means pore. And Korea manages salicylic acid with a number, AHA with a sentence.

Next in the series: how to read an ingredient list in order (Ingredient Guide 14).

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📌 Earlier guides

📌 Glycolic Acid (AHA) – What the Research Shows and How Much Is Safe

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

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

📌 Dark Spots, Acne, Pores, Lines: Which Ingredient First

About the author · Dr. J

📄 References

· Enforcement Rule of the Cosmetics Act (Korea), Annex 3 — precautions for AHA-containing products, item 11

· Regulation on Cosmetic Safety Standards (Korea), Annex 2 — restricted ingredients, salicylic acid

· 21 CFR 333.310 — Topical acne drug products, active ingredients (US eCFR)

· U.S. FDA, Alpha Hydroxy Acids — 18% rise in UV sensitivity after four weeks; 2005 Sunburn Alert guidance; CIR conditions

· Arif T. Clin Cosmet Investig Dermatol 2015 — the review describing salicylic acid as lipid soluble and miscible with sebaceous lipids

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This article summarises regulatory texts and published research. It is information, not a diagnosis or a treatment plan. If something about your skin worries you, please talk to a professional.

— Dr. J Ingredient Notes

September 21, 2026

Salicylic Acid (BHA): 0.5% vs 2%, Explained – Why the Label Numbers Differ (Ingredient Guide 8)

Cover image for Ingredient Guide 8 on salicylic acid (BHA): how to read the 0.5 percent, 2 percent and 3 percent limits on Korean cosmetic labels, and what an 8-week trial in 30 people with acne found. Dr. J Ingredient Notes.

Hello, this is Dr. J.

Ingredient Guide number eight is salicylic acid – the ingredient most labels shorten to BHA.

If you shop for acne or pore products, you will see this name often. What you will also see is that the number on the back changes from product to product: 2% on one cleanser, 0.5% on a toner, 3% on a scalp product.

Here is the surprising part. In Korea, salicylic acid does not have one limit. The same ingredient is capped at 0.5%, 2% or 3% depending on what it is used for. This post explains how to read those numbers, and then walks through two 8-week trials.

🇰🇷 Read this in Korean: 살리실산 BHA, 0.5%와 2% 읽는 법 (성분 백과 ⑧)

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📄 Read the sources first

· Korea MFDS, Regulation on Cosmetic Safety Standards, Annex 2 – restricted ingredients (Korean)

· Bilal H et al., Pharmaceuticals 2023 – 30 people with acne, 2% gel, 8 weeks (open access)

· Li S et al., J Cosmet Dermatol 2023 – randomized trial of a salicylic acid serum, 8 weeks

· Arif T, Clin Cosmet Investig Dermatol 2015 – review (open access)

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

Annex 2 lists the limit for each product category on one line, with a note about children’s products. Salicylic acid appears in two tables – preservatives and other restricted ingredients – so check both.

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15-second summary · no sound

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The four lines, if you are in a hurry

✔ Salicylic acid is lipid-soluble, so it mixes with sebum. That is where it parts ways with water-soluble AHAs

✔ The 0.5% · 2% · 3% on Korean labels are not strength levels – they are use categories: preservative, rinse-off cleanser active, rinse-off hair-product active

✔ 30 people with acne used a 2% gel twice daily for 8 weeks: lesion counts and severity scores fell significantly

✔ In a randomized trial, 83 people completed 8 weeks of a salicylic acid serum: pore density, sebum and comedones improved

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Lipid-soluble – where BHA parts ways with AHA

Salicylic acid is a beta hydroxy acid, BHA. The name looks like glycolic acid (AHA), which I covered in Guide 2, but the two behave differently.

✔ Glycolic acid dissolves in water – it works at the skin surface

✔ Salicylic acid dissolves in oil – it mixes with sebum and reaches into the pore

A 2015 review puts it this way: salicylic acid, unlike the alpha hydroxy acids, is a lipid-soluble agent, miscible with the lipids of the epidermis and with the sebaceous-gland lipids inside hair follicles. That is why it comes up for comedone-prone skin. The review also places its calming, anti-inflammatory action in the 0.5–5% range – Arif T, 2015.

So the question is less “AHA or BHA, which is better?” and more “is my concern at the surface, or in the pore?” Dullness and rough texture have the AHA evidence; sebum and comedones have the BHA evidence.

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How to read the numbers – 0.5%, 2% and 3% are use categories

A higher number does not mean a stronger product. Korea’s cosmetic safety standard (Annex 2) sets a separate limit for each use. I read the Korean text and keep the categories as written; other markets set their own limits.

Number on the label	Used as	Product type
0.5%	Preservative	Limit in the preservatives table
2%	Active in a “functional cosmetic”	Rinse-off cleansers for the body and face
3%	Active in a “functional cosmetic”	Rinse-off hair products

The same table adds two notes.

✔ Not permitted in products for infants, or in products labeled as suitable for children aged 13 and under (shampoo excepted)

✔ The 2% and 3% limits apply only when the product has been reviewed as a functional cosmetic; other products may not use it as an active

“Functional cosmetic” is a Korean regulatory category – a product whose specific claim, such as “soothes acne-prone skin,” has been reviewed by the MFDS. That is why 2% in Korea almost always appears on a rinse-off cleanser with that claim. The small numbers on leave-on toners and serums are either within the preservative limit or belong to a related ingredient with a different name – see the next table.

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Finding it on the ingredient list – four names in the salicylic family

Name on the list (INCI)	What it is
Salicylic Acid	The ingredient itself. The limits above apply to this name
Capryloyl Salicylic Acid (LHA)	Salicylic acid with a fatty-acid tail attached. It was paired with salicylic acid in the 83-person serum trial
Betaine Salicylate	Salicylic acid combined with betaine. Common in leave-on products, especially Korean ones
Salix Alba (Willow) Bark Extract	A plant extract. Not salicylic acid itself, so it sits outside the limits above

A different name means a different limit and a different body of research. Read the numbers in this post against the Salicylic Acid line only.

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What the research found – 30 people for 8 weeks, 83 people for 8 weeks

First, 30 people with acne. Thirty acne patients – 12 men and 18 women, average age 22 – used a 2% salicylic acid gel twice daily for 8 weeks, alongside a control group of 10. Total lesion counts and the Global Acne Grading System (GAGS) score fell significantly (p<0.001). Two people had mild dryness and flaking that settled within a week – Bilal et al., Pharmaceuticals 2023. The paper is open access, so the tables are one click away above.

Second, 93 people randomized. A serum containing salicylic acid and lipohydroxy acid was tested over 8 weeks; 93 people were randomized and 83 completed. One group used the serum, the other added a mask. Both groups improved on acne severity, skin-tone evenness, pore density, pigmentation, sebum output, comedones and hydration (P<0.05); the mask group did slightly better on closed comedones and acne severity. No adverse events were reported – Li et al., J Cosmet Dermatol 2023.

Study	People · duration	What was used	What was found
Bilal 2023	30 · 8 weeks	2% gel, twice daily	Lesion count and severity score fell (p<0.001)
Li 2023	93 randomized · 83 completed · 8 weeks	Salicylic acid + LHA serum (± mask)	Pore density, sebum, comedones improved (P<0.05)
Arif 2015	Review	—	Lipid-soluble; calming action in the 0.5–5% range

Both trials ran for 8 weeks. It is not an ingredient to judge after a few days. And with 30 and 83 participants, both are real but small – I would not stretch them to “works for everyone.” This post stays with cosmetic use and leaves professional peel studies aside.

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How to use it – order and pairing

✔ Start at 2–3 nights a week. If skin feels dry or stings, cut back

✔ A rinse-off product goes in the cleansing step; a leave-on product goes right after cleansing, followed by moisturizer

✔ On nights you use glycolic acid (AHA) or retinol, alternate the days. Do not stack all three in one evening

✔ Soothing and barrier ingredients – niacinamide, ceramides, panthenol – can sit in the same routine

✔ Wear sunscreen the next morning

✔ If you are pregnant or sensitive to aspirin, ask a professional before starting

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 it rinse-off or leave-on? – that is where the limits split

✔ Is the name “Salicylic Acid,” or one of the related names? – check the four-name table above

✔ Where does it sit on the ingredient list? – higher means more. Ingredients at 1% or below may be listed in any order, so a low position is not unusual

✔ Is there a percentage on the front? – if not, the list order is your only clue

✔ Is the product labeled for children 13 and under? – in Korea it cannot contain salicylic acid (shampoo excepted)

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

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In one line

🧪 Salicylic acid works because it is lipid-soluble. The number on the label tells you the use, not the strength – and two 8-week trials show what it did for lesions, pores and sebum.

Next in the Ingredient Guide: tranexamic acid (Guide 9) – the name that keeps coming up for dark spots.

📌 Earlier posts

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

· 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

About the author · Dr. J

📄 References

· Korea MFDS, Regulation on Cosmetic Safety Standards, Annex 2 – Salicylic Acid and its salts

· Bilal H et al., Pharmaceuticals 2023;16(1):87 – 2% salicylic acid gel, 30 people, 8 weeks

· Li S et al., J Cosmet Dermatol 2023 – randomized trial of a salicylic acid/LHA serum, 93 randomized, 83 completed, 8 weeks

· Arif T, Clin Cosmet Investig Dermatol 2015;8:455-461 – review

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

September 16, 2026