The Cosmetic Peptide Encyclopedia: Every Common Skincare Peptide, A to Z

An A–Z reference to cosmetic peptides in skincare, hair care and eye care - INCI names, trade names, what each is used for, and an honest rating of the published evidence, with sources.

By the Glow Cosmetics Editorial Team. Updated .

Quick answer

Cosmetic peptides are short chains of amino acids used in skincare, grouped as signal peptides (e.g., palmitoyl pentapeptide-4), carrier peptides (copper tripeptide-1), neurotransmitter-inhibiting peptides (acetyl hexapeptide-8) and enzyme-inhibiting peptides. Of the dozens on the market, only a handful have placebo-controlled human trials - palmitoyl pentapeptide-4 and acetyl hexapeptide-8 for wrinkles, and palmitoyl tripeptide-8 for sensitive-skin stinging. Most others rely on lab, combination-product or supplier data. This A–Z lists each one with its evidence level.

  • Four main types: signal, carrier, neurotransmitter-inhibiting and enzyme-inhibiting peptides.
  • Strongest single-peptide human evidence: palmitoyl pentapeptide-4 (wrinkles), acetyl hexapeptide-8 (mixed), palmitoyl tripeptide-8 (sensitive skin).
  • Many famous trade-name peptides have no standalone peer-reviewed human trial.
  • Penetration through the skin barrier is the main scientific limitation for most peptides.

This is our living reference to the peptides you'll find on skincare, hair-care and eye-care labels. For each one we list its INCI name (the standardized name on ingredient lists), common trade names, what it's used for, and an honest evidence rating based on peer-reviewed literature we verified on PubMed.

How to read this guide

The four types of cosmetic peptides

Reviews generally sort topical peptides into four groups (Gorouhi & Maibach, 2009; Errante et al., 2020):

  • Signal peptides: prompt skin cells to support collagen, elastin and matrix production.
  • Carrier peptides: deliver trace elements like copper.
  • Neurotransmitter-inhibiting peptides: designed to soften expression lines.
  • Enzyme-inhibiting peptides: slow enzymes that break down skin proteins.

Our evidence ratings

Rating Meaning
Moderate At least one adequately designed, placebo/vehicle-controlled human trial of the peptide itself
Limited Small, short, open-label or multi-ingredient human studies; or mixed results
Preclinical Lab (cell, skin explant) or animal studies only
Supplier data No peer-reviewed human efficacy study found; claims come from ingredient suppliers

A low rating doesn't mean an ingredient doesn't work; it means the public, peer-reviewed proof isn't there yet. Reviewers consistently note that peptide clinical evidence is "often weak", penetration is a key limitation, and many results "have not been published in scientific journals" (Pai et al., 2017; Schagen, 2017; Pintea et al., 2025).

Quick reference table

INCI name Trade name Type Used for Evidence
Acetyl dipeptide-1 cetyl ester (various) Neuro-soothing Sensitive skin, stinging Limited
Acetyl dipeptide-31 amide (various) Anti-inflammatory signal Calming, firmness Limited
Acetyl hexapeptide-8 (-3) Argireline Neurotransmitter Expression lines Limited (mixed)
Acetyl octapeptide-3 SNAP-8 Neurotransmitter Expression lines Supplier data
Acetyl tetrapeptide-3 Capixyl (with red clover) Signal Thinning-looking hair Limited
Acetyl tetrapeptide-5 Eyeseryl Signal Under-eye puffiness Supplier data
Biotinoyl tripeptide-1 Procapil (blend) Signal Hair & scalp Limited
Carnosine — Antioxidant dipeptide Glycation, oxidative stress Preclinical
Copper tripeptide-1 GHK-Cu Carrier / signal Firmness, smoothness, scalp Limited (skin), Preclinical (hair)
Dipeptide diaminobutyroyl benzylamide diacetate Syn-Ake Neurotransmitter Expression lines Preclinical
Dipeptide-2 (+ palmitoyl tetrapeptide-7) Eyeliss Signal Under-eye bags Supplier data
Hexapeptide-9 (various) Signal Wrinkles Limited
Hexapeptide-11 — Signal Elasticity Limited
Myristoyl pentapeptide-17 (lash serums) Signal Lashes & brows Supplier data
Palmitoyl pentapeptide-4 Matrixyl Signal Wrinkles, fine lines Moderate
Palmitoyl tripeptide-1 + palmitoyl tetrapeptide-7 Matrixyl 3000 Signal Wrinkles, firmness Limited
Palmitoyl tripeptide-5 Syn-Coll Signal Collagen support Supplier data
Palmitoyl tripeptide-8 Neutrazen Neuro-soothing Sensitive skin, redness Moderate (one RCT)
Palmitoyl tripeptide-38 Matrixyl synthe'6 Signal Wrinkles Limited
Pentapeptide-18 Leuphasyl Neurotransmitter Expression lines Preclinical
sh-Oligopeptide-1 EGF Growth-factor-like Texture, firmness Limited
Tripeptide-10 citrulline Decorinyl Signal Collagen organization Limited

Peptides A–Z

Acetyl dipeptide-1 cetyl ester

A soothing peptide designed to calm skin's sensory nerve response. In a 31-woman split-face study, a product containing it relieved capsaicin-induced facial burning within 15 minutes, though a competitor's product acted faster (Schoelermann et al., 2016). Evidence: Limited. See peptides for sensitive skin.

Acetyl dipeptide-31 amide

A newer anti-inflammatory peptide that reduced several inflammatory signals in lab tests, with a 16-week clinical study reporting improvements in sagging and lines (Edison et al., 2025). Evidence: Limited (industry data).

Acetyl hexapeptide-8 (Argireline)

The best-known neurotransmitter-inhibiting peptide, designed to soften expression lines. A 4-week placebo-controlled trial of 60 people found 48.9% subjective improvement vs 0% placebo (Wang et al., 2013), but an independent split-face study found no significant effect (Henseler, 2023). The CIR panel found it safe up to 0.005% (Johnson et al., 2025). Evidence: Limited (mixed). Full guide: Argireline.

Acetyl octapeptide-3 (SNAP-8)

A longer relative of Argireline. It appears in peer-reviewed literature only inside multi-ingredient microneedle patches (Shin et al., 2024). Evidence: Supplier data for standalone use.

Acetyl tetrapeptide-3 (Capixyl)

A signal peptide usually combined with red clover extract for hair. In a 24-week randomized trial of 32 people, a combination containing it increased terminal hair count by 8.3% vs 8.7% for 3% minoxidil, with no significant difference (Lueangarun & Panchaprateep, 2020). Evidence: Limited. See peptides for hair.

Acetyl tetrapeptide-5 (Eyeseryl)

Marketed for under-eye puffiness. Peer-reviewed data are limited to a cell study of a peptide mixture (Wu et al., 2021). Evidence: Supplier data. See peptides for under-eye bags.

Biotinoyl tripeptide-1 (Procapil)

Biotin linked to a peptide, often blended with apigenin and oleanolic acid for scalp care. Published human data are limited to a research letter (Samadi et al., 2024). Evidence: Limited.

Carnosine

A naturally occurring antioxidant dipeptide. A carnosine cream reduced markers of glycation in human skin samples (Narda et al., 2018), and it reduced oxidative damage after simulated sunlight in skin explants (Girardi et al., 2024). Evidence: Preclinical.

Copper tripeptide-1 (GHK-Cu)

A naturally occurring peptide-copper complex that supports collagen, elastin and glycosaminoglycan production in lab studies (Pickart & Margolina, 2018). Human facial studies were mostly unpublished conference reports, and a 2026 evidence map called it "promising but unproven" (Mateescu et al., 2026). Evidence: Limited (skin), Preclinical (hair). Full guide: copper peptides.

Dipeptide diaminobutyroyl benzylamide diacetate (Syn-Ake)

A small peptide-like molecule modeled on a snake-venom compound, marketed for expression lines. Peer-reviewed data are computational and cell-based (Gok et al., 2024). Evidence: Preclinical.

Dipeptide-2 (Eyeliss)

Combined with palmitoyl tetrapeptide-7 and hesperidin methyl chalcone in the Eyeliss complex, marketed for under-eye bags. No peer-reviewed human trial found. Evidence: Supplier data.

Hexapeptide-9

A collagen-derived signal peptide. A 96-person randomized trial found a cyclized version outperformed vehicle and low-dose (0.002%) retinol over 56 days (Chang et al., 2025); results may not apply to standard hexapeptide-9. Evidence: Limited.

Hexapeptide-11

A peptide that activated cell "housekeeping" pathways in lab studies; a 25-person, 4-week toner test reported improved elasticity (Sklirou et al., 2015). Evidence: Limited (supplier-run).

Myristoyl pentapeptide-17

A common lash- and brow-serum peptide. We found no peer-reviewed study on it. Evidence: Supplier data.

Palmitoyl pentapeptide-4 (Matrixyl)

A signal peptide modeled on a collagen-precursor fragment, with the strongest single-peptide trial in skincare: 12 weeks, double-blind, placebo-controlled, 93 women, significant reductions in wrinkles and fine lines (Robinson et al., 2005). Evidence: Moderate. Full guide: Matrixyl.

Palmitoyl tripeptide-1 + palmitoyl tetrapeptide-7 (Matrixyl 3000)

One of the most widely used peptide blends (Ferreira et al., 2020). A human tape-strip study found both peptides in the outer skin layer (Trzaska et al., 2026); efficacy data come from multi-ingredient products. Evidence: Limited.

Palmitoyl tripeptide-5 (Syn-Coll)

Marketed to support collagen. No standalone peer-reviewed human trial found; it appears in multi-ingredient microneedle studies (Avcil et al., 2020). Evidence: Supplier data.

Palmitoyl tripeptide-8 (Neutrazen)

A soothing peptide for sensitive skin. In a 56-person, double-blind, vehicle-controlled trial, it reduced capsaicin-provoked stinging significantly more than its vehicle over 14 days (Fatemi et al., 2016). Evidence: Moderate (one RCT).

Palmitoyl tripeptide-38 (Matrixyl synthe'6)

A matrix-signaling peptide found in multi-ingredient serums with positive open-label results (Lintner et al., 2020). Evidence: Limited.

Pentapeptide-18 (Leuphasyl)

Targets a different step of the nerve-to-muscle signal than Argireline. Peer-reviewed data are computational and cell studies only (Akhan et al., 2026). Evidence: Preclinical.

sh-Oligopeptide-1 (EGF)

A lab-made version of epidermal growth factor. Small open-label and pilot studies report improved texture (Schouest et al., 2012), while a 2026 randomized pilot found global wrinkle ratings "changed minimally" (Abud et al., 2026). Evidence: Limited.

Tripeptide-10 citrulline (Decorinyl)

Mimics part of decorin, a protein that organizes collagen fibers; lab data show more uniform collagen fibrils (Puig et al., 2008), with limited human data in combination (Raikou et al., 2017). Evidence: Limited.

Peptides by concern

Frequently asked questions

What are the main types of peptides in skincare?

Signal peptides (support collagen and matrix), carrier peptides (deliver trace elements like copper), neurotransmitter-inhibiting peptides (soften expression lines), and enzyme-inhibiting peptides (slow the breakdown of skin proteins).

Which skincare peptides have the best evidence?

Palmitoyl pentapeptide-4 (Matrixyl) has the strongest single-peptide trial for wrinkles. Acetyl hexapeptide-8 (Argireline) has one positive placebo-controlled trial and one independent null study. Palmitoyl tripeptide-8 has a vehicle-controlled trial for sensitive-skin stinging.

How do I find peptides on an ingredient list?

Look for names containing "peptide" (for example, palmitoyl pentapeptide-4, acetyl hexapeptide-8, copper tripeptide-1). Trade names like Matrixyl or Argireline won't appear on the INCI list; the chemical names will.

Do peptides penetrate the skin?

Many peptides are larger than the ~500 dalton size that passes easily through skin, which is a recognized limitation. Human studies of some peptides have found them in the outermost skin layer; formulation and delivery matter a lot.

Are peptides safe?

Cosmetic peptides are generally well tolerated and are among the gentler active ingredients. Safety panels have reviewed specific peptides; for example, the CIR panel found acetyl hexapeptide-8 amide safe up to 0.005% as used.

Sources

  1. Gorouhi F, Maibach HI. Role of topical peptides in preventing or treating aged skin. Int J Cosmet Sci. 2009;31(5):327-345. https://pubmed.ncbi.nlm.nih.gov/19570099/
  2. Errante F, et al. Cosmeceutical Peptides in the Framework of Sustainable Wellness Economy. Front Chem. 2020;8:572923. https://pubmed.ncbi.nlm.nih.gov/33195061/
  3. Pai VV, Bhandari P, Shukla P. Topical peptides as cosmeceuticals. Indian J Dermatol Venereol Leprol. 2017;83(1):9-18. https://pubmed.ncbi.nlm.nih.gov/27451932/
  4. Schagen SK. Topical Peptide Treatments with Effective Anti-Aging Results. Cosmetics. 2017;4(2):16. https://doi.org/10.3390/cosmetics4020016
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  6. Schoelermann AM, et al. Comparison of skin calming effects of cosmetic products containing 4-t-butylcyclohexanol or acetyl dipeptide-1 cetyl ester on capsaicin-induced facial stinging in volunteers with sensitive skin. J Eur Acad Dermatol Venereol. 2016;30 Suppl 1:18-20. https://pubmed.ncbi.nlm.nih.gov/26805418/
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  8. Wang Y, et al. 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. https://pubmed.ncbi.nlm.nih.gov/23417317/
  9. Henseler H. Investigating the effects of Argireline in a skin serum containing hyaluronic acids on skin surface wrinkles using the Visia Complexion Analysis camera system. GMS Interdiscip Plast Reconstr Surg DGPW. 2023;12:Doc09. https://pubmed.ncbi.nlm.nih.gov/38024099/
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  11. Shin JY, et al. Clinical Safety and Efficacy Evaluation of a Dissolving Microneedle Patch Having Dual Anti-Wrinkle Effects With Safe and Long-Term Activities. Ann Dermatol. 2024;36:215-224. https://pubmed.ncbi.nlm.nih.gov/39082657/
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