Peptides: How to Read the Numbers in the Name – Penta and Hexa Are Counts, Palmitoyl Is the Carrier, and Why 12 Weeks (Ingredient Guide 10)

Hello, this is Dr. J.

Ingredient Guide number ten is peptides – the long names on the back of wrinkle and firming products, like Palmitoyl Pentapeptide-4 or Acetyl Hexapeptide-8.

Here is the surprising part. The landmark trial for this ingredient used 3 ppm – that is 0.0003%. So finding a peptide near the bottom of an ingredient list is not a red flag. This post explains how to read the numbers and prefixes inside those long names, and then looks at what two trials on real people found.

The short version: peptides are a family in which the evidence differs from one name to the next, so you choose by reading the full name rather than the word “peptide” – and the benchmark is 12 weeks.

🇰🇷 Read this in Korean: 펩타이드 크림, 이름 속 숫자 읽는 법 (성분 백과 ⑩)

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📄 Read the sources first

· Robinson LR et al., Int J Cosmet Sci 2005;27(3):155–160 – palmitoyl pentapeptide 3 ppm, 93 women, 12 weeks, split-face

· Wang Y et al., Am J Clin Dermatol 2013;14(2):147–153 – acetyl hexapeptide, 60 people, 4 weeks, placebo-controlled

· Schagen SK, Cosmetics 2017;4(2):16 – a review of cosmetic peptides by type (open access)

· 🏠 COSMILE Europe ingredient database – paste the full INCI name to look it up

The 2005 trial compared the two sides of the same face; the 2013 trial had a separate placebo group. Both designs are spelled out in the abstracts.

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15-second summary · no sound

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In a hurry? Four lines

✔ A peptide is a short chain of a few amino acids. If collagen is the long chain, a peptide is a fragment of it

✔ Penta, hexa, tri in the name is the amino-acid count. The trailing “-4” or “-8” is a registry index, so a bigger number is not a stronger product

✔ 93 women who applied palmitoyl pentapeptide at 3 ppm for 12 weeks saw fine lines improve significantly versus placebo; in 60 people who applied acetyl hexapeptide for 4 weeks, 48.9% were rated improved versus 0% on placebo

✔ Peptides are not on Korea’s list of four approved wrinkle ingredients. An “anti-wrinkle functional” claim means a listed ingredient is included or an individual review was done

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What a peptide is – a fragment of collagen

A protein is a chain of hundreds or thousands of amino acids. Cut a few to a few dozen of them off that chain and you have a peptide. That is why the names carry a count: penta (5), hexa (6), tri (3).

In the collagen guide I explained that topical collagen is too large to get in. Peptides are the answer to exactly that problem: they shrink the molecule. This is not an ingredient that works because it is big. It works because it is small.

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How they work – “make more” and “move less”

Peptides are not one thing. A 2017 review sorts cosmetic peptides into three groups by what they do – Schagen, Cosmetics 2017.

Group	Typical name (as listed)	What it does	Human trial
Signal peptide	Palmitoyl Pentapeptide-4 (Pal-KTTKS)	Resembles a collagen fragment and is designed to tell skin cells to make more collagen	93 women · 12 weeks · 3 ppm (2005)
Neurotransmitter-modulating peptide	Acetyl Hexapeptide-8 (formerly -3)	Patterned on the end of SNAP-25, the protein that passes the “move” signal to muscle, so it dampens that signal where expression lines form	60 people · 4 weeks (2013)
Carrier peptide	Copper Tripeptide-1 (GHK-Cu)	Binds copper and carries it into the skin	The review cites small studies, but I could not read the originals, so no figures appear in this post

Same word, different jobs – and a different depth of human evidence behind each. This post therefore centres on the two names above that have trials in people.

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Reading the numbers – penta, hexa, palmitoyl and ppm

Split “Palmitoyl Pentapeptide-4” into three pieces and it reads itself.

Piece	Meaning	How to read it
Palmitoyl	A fatty-acid tail. It helps a water-loving peptide cross the oily stratum corneum	When it is there, the molecule was designed with penetration in mind
Penta · Hexa · Tri	Amino-acid count – 5 · 6 · 3	More amino acids does not mean stronger. Which name it is matters more
-4 · -8	A registry index in the international naming system (INCI)	“-8 beats -3” is a misreading. Acetyl Hexapeptide-3 and -8 are the old and new names of the same ingredient
ppm	Parts per million. 3 ppm = 0.0003%	Trial doses are in this unit, so a peptide sitting near the bottom of the list is normal. Ingredients under 1% may be listed in any order

In short, the numbers in the name are size and index, not strength. Strength is what the trials below are for.

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What the trials found – 93 women for 12 weeks, 60 people for 4 weeks

First, 93 women. Caucasian women aged 35–55 applied a moisturiser to one side of the face and the same moisturiser with palmitoyl pentapeptide at 3 ppm to the other, for 12 weeks, in a double-blind, placebo-controlled, left-right randomised design. Both instrument measurements and expert graders found fine lines and wrinkles improved significantly versus placebo, and the women’s own assessments agreed. The peptide was well tolerated – Robinson et al., Int J Cosmet Sci 2005.

Second, 60 people. Sixty Chinese subjects were assigned 3:1 to acetyl hexapeptide or placebo, applied to the crow’s-feet area twice daily for 4 weeks. In the subjective assessment, total anti-wrinkle efficacy was 48.9% in the peptide group and 0% on placebo, and roughness parameters measured from silicone replicas all fell in the peptide group (p<0.01) with no clear change on placebo – Wang et al., Am J Clin Dermatol 2013.

Trial	People · duration	What was used	What was found
Robinson 2005	93 women · 12 weeks	Palmitoyl pentapeptide 3 ppm (split-face)	Fine lines significantly improved vs placebo · well tolerated
Wang 2013	60 people · 4 weeks	Acetyl hexapeptide (eye area, twice daily)	Rated improved 48.9% vs 0% · roughness fell (p<0.01)

Read together, the two trials say this. The two peptides with clear names have evidence in people; where the abstract gives no individual percentage, as in 2005, this post says “significantly” and leaves it there. One study delivered a result at 4 weeks, but for the “make more collagen” route the benchmark is 12 weeks. And peptides outside these two names may have a different level of evidence, so the sensible move is to read the name on the box and look up that name.

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On a Korean label – reading the “anti-wrinkle functional” claim

In Korea, a product can carry an anti-wrinkle claim only if it uses an ingredient and level approved by the Ministry of Food and Drug Safety, or passes an individual review with safety and efficacy data (Cosmetics Act, Article 4). The approved wrinkle ingredients are four: retinol, retinyl palmitate, adenosine and polyethoxylated retinamide. Peptides are not among them. Other countries regulate claims differently; the studies themselves are the same everywhere.

What the label shows	What it means
“Anti-wrinkle functional cosmetic” + adenosine or retinol in the list	Likely registered on the strength of the listed ingredient. The peptide is along for the ride
“Anti-wrinkle functional cosmetic” + no listed ingredient	Passed an individual review, with the peptide or another unlisted active
No claim · peptide in the list	An ordinary cosmetic. The ingredient is there but the claim cannot be printed. That does not mean the ingredient is idle

So the claim tells you a product went through a review, not that it is stronger. It is the same structure as the “whitening” claim in the tranexamic acid guide.

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How to use it – gentle enough to go almost anywhere

✔ Morning and evening are both fine. After serum, before cream

✔ It shares a routine comfortably with retinol and niacinamide. It is low-irritation, which makes it an easy first active

✔ For expression lines, acetyl hexapeptide was tested on the crow’s-feet area. Pat a thin layer on exactly that spot

✔ In the morning, sunscreen is half the job. A signal to make collagen goes nowhere if sunlight keeps breaking it down

Which ingredients can share a night is in the ingredient compatibility chart.

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Five things to check before you buy

✔ Which peptide? – read the full name on the ingredient list, not the word “peptide” on the front. The names with human trials are above

✔ Is there a “palmitoyl” in front? – a sign the molecule was designed to get in

✔ Is there an anti-wrinkle functional claim? – if so, a listed ingredient is included or an individual review was done

✔ Is it near the bottom of the list? That is fine – trial doses are in ppm. Do not judge by position

✔ Can you give it 12 weeks? – that is how long the collagen-signal trial ran. One jar is too short to judge

Save these five lines for the shop. Reading the back of the box takes five minutes.

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One-line summary

🧪 Peptides are an ingredient you choose by reading the name. Penta and hexa are counts, the trailing number is an index, palmitoyl is the carrier – pick a name that has been tested in people and give it 12 weeks, and you are close to what the trials saw.

The next Ingredient Guide is sunscreen: how to read SPF and PA (Ingredient Guide 11) – starting with what the number and the plus signs actually measure.

📌 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

· Collagen: Topical vs Oral – What the Research Says (Ingredient Guide 5)

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

· Dull, Rough Skin? Glycolic Acid (AHA) – What the Research Shows

📄 References

· Robinson LR, Fitzgerald NC, Doughty DG, Dawes NC, Berge CA, Bissett DL. Topical palmitoyl pentapeptide provides improvement in photoaged human facial skin. Int J Cosmet Sci 2005;27(3):155–160

· Wang Y, Wang M, Xiao S, Pan P, Li P, Huo J. The anti-wrinkle efficacy of argireline, a synthetic hexapeptide, in Chinese subjects: a randomized, placebo-controlled study. Am J Clin Dermatol 2013;14(2):147–153

· Schagen SK. Topical Peptide Treatments with Effective Anti-Aging Results. Cosmetics 2017;4(2):16

· Korea Cosmetics Act, Article 4 · Regulation on the Review of Functional Cosmetics – listed ingredients and individual review

This article summarises published research and public documents for information. It is not a diagnosis or a treatment. If you have a skin concern that worries you, please see a professional.

— Dr. J Ingredient Notes