Peptides for Hair: What the Research Says About Hair Growth, Thinning and Hair Loss

Copper peptides, biotinoyl tripeptide-1, acetyl tetrapeptide-3, lash peptides. We review the real evidence for peptides in hair and scalp care, what results are realistic, and when to see a dermatologist.

By the Glow Cosmetics Editorial Team. Updated .

Quick answer

Peptides are promising in hair and scalp care, but the evidence is still early. Copper peptides have shown follicle-stimulating effects only in lab and animal studies. Acetyl tetrapeptide-3 (often combined with red clover extract as Capixyl) has the best human data; in one small 24-week trial a combination containing it performed similarly to 3% minoxidil. Topical peptide products are cosmetics that condition the scalp and help hair look healthier. They are not a proven treatment for hair loss, so see a dermatologist for significant or sudden shedding.

  • The most-discussed hair peptides are copper peptides (GHK-Cu, AHK-Cu), biotinoyl tripeptide-1 (Procapil), acetyl tetrapeptide-3 (Capixyl) and lash peptides such as myristoyl pentapeptide-17.
  • Copper peptide hair data comes from lab and animal studies. We found no published placebo-controlled human trial of topical GHK-Cu for hair.
  • The best human study is a small 24-week trial (n=32) where an acetyl tetrapeptide-3 combination raised terminal hair count 8.3%, versus 8.7% for 3% minoxidil, with no significant difference between them.
  • A 2025 review found hair-peptide studies are mostly small, combination-based and often industry-linked.
  • Healthy-looking hair starts with a comfortable scalp. Scalp care is where cosmetic peptides fit best today.

Search "peptides for hair growth" and you'll find bold promises. The science is genuinely interesting, but it's earlier-stage than most marketing suggests. This guide separates what's been shown in people from what's only been seen in the lab, so you can make a sensible choice.

Important: Hair loss can have many causes, including genetics, hormones, thyroid problems, nutrition, stress, medications and scalp conditions. If you notice sudden shedding, patches of hair loss, or a scalp that is itchy, scaly or painful, see a board-certified dermatologist. Cosmetic products care for your scalp and hair; they don't diagnose or treat medical conditions.

Why peptides for hair?

Hair grows from follicles, tiny organs in the scalp that cycle through growth (anagen), transition (catagen) and resting (telogen) phases. The dermal papilla, a cluster of cells at the base of each follicle, acts as its control center.

Researchers are interested in peptides because some appear to influence these cells in the lab, for example by encouraging dermal papilla cells to multiply or by affecting signals linked to the growth phase. The open question is whether a peptide applied to the scalp reaches the follicle in enough quantity to make a visible difference. That's what clinical studies have to show.

The main hair peptides, and the evidence for each

Copper peptides (GHK-Cu and AHK-Cu)

What the research shows: Copper peptides have the longest research history in hair, but it's almost all lab and animal work:

  • In the early 1990s, a copper-binding peptide enlarged hair follicles in rats, an effect researchers described as similar to topical minoxidil (Uno & Kurata, 1993). Copper peptide complexes were also studied in mice (Trachy et al., 1991).
  • In a 2007 lab study, the copper peptide AHK-Cu (a close relative of GHK-Cu) stimulated the elongation of human hair follicles kept alive outside the body and boosted the growth of dermal papilla cells (Pyo et al., 2007). Note that this study tested AHK-Cu, not GHK-Cu, even though it's often cited as a "GHK-Cu hair study".
  • Reviews by GHK-Cu's original researchers list increased follicle size among its effects (Pickart, 2008; Pickart & Margolina, 2018). Those reviews come from the peptide's discoverer, who has commercial ties to it.

The honest summary: promising biology, but we could not find a published, placebo-controlled human trial of topical GHK-Cu for hair growth. Copper peptides are a reasonable ingredient in a scalp-care product; they aren't a proven hair-loss treatment.

Acetyl tetrapeptide-3 (often sold as Capixyl)

Acetyl tetrapeptide-3 is usually combined with red clover extract (a source of biochanin A). It has the most interesting human data of the hair peptides.

In a 24-week, randomized, triple-blind trial of 32 people with mild-to-moderate androgenetic (pattern) hair loss, a formula containing biochanin A, acetyl tetrapeptide-3 and ginseng increased terminal hair count by 8.3%, compared with 8.7% for 3% minoxidil, with no significant difference between the two. One person using minoxidil developed scalp eczema; nobody in the peptide-combination group had a local reaction (Lueangarun & Panchaprateep, 2020).

That's encouraging, with caveats: the trial was small, had no placebo group, and tested a multi-ingredient formula, so the peptide's own contribution can't be separated out.

Biotinoyl tripeptide-1 (often sold as Procapil)

Biotinoyl tripeptide-1 combines biotin with a peptide. It's frequently paired with apigenin and oleanolic acid. It's widely used in hair serums, but published human data is thin: a 2024 research letter evaluated a caffeine + Procapil formula in male pattern hair loss (Samadi et al., 2024), and most other data comes from ingredient suppliers.

Myristoyl pentapeptide-17 and lash peptides

Myristoyl pentapeptide-17 is a common ingredient in lash and brow serums. We could not find a peer-reviewed study on it. The best published lash data we found is an open-label 12-week study of 30 women using a lash serum with peptides and glycosaminoglycans. Lashes measured 8.3% longer, 10.1% wider and 14.1% greater in volume versus baseline, with no adverse effects (Fernandez-Gonzalez et al., 2024). There was no control group, and the specific peptides weren't named.

What independent reviews conclude

A 2025 review of 24 studies and technical files on topical alternatives such as Redensyl, Procapil, Capixyl and Baicapil found the ingredients were mostly studied in combinations, with "limited sample size, lack of comparison with standard therapies, … nondisclosure of the type of alopecia treated, and conflicts of interest." The author suggested they may have a role as an add-on or for people who can't tolerate standard treatments (Bikash, 2025). Another 2025 review of hair cosmeceuticals reached a similar conclusion (Pan et al., 2025).

Evidence at a glance

Peptide What it's used for Best evidence Evidence level
Copper peptides (GHK-Cu, AHK-Cu) Scalp & follicle support Lab (ex vivo follicles) and animal studies Preclinical only
Acetyl tetrapeptide-3 (+ red clover) Thinning-looking hair 24-week RCT, n=32, combination vs. 3% minoxidil Limited
Biotinoyl tripeptide-1 Thinning-looking hair Research letter; supplier data Limited
Myristoyl pentapeptide-17 Lashes & brows No peer-reviewed study found Very limited
Peptide lash serums (unnamed peptides) Lashes Open-label 12-week study, n=30 Limited

Where peptides fit in a hair routine today

Given the evidence, the most sensible role for cosmetic peptides is scalp and hair care: keeping the scalp comfortable and conditioned and helping hair look healthy, alongside the basics that matter most.

  1. Cleanse gently. Harsh shampoos can leave the scalp tight and irritated. Our Gentle Daily Shampoo uses mild cleansers with panthenol and glycerin.
  2. Condition the lengths. Conditioner reduces friction and the look of breakage while combing. Try the Smooth + Strength Conditioner.
  3. Leave-on scalp serum. This is where peptides make the most sense, because they stay on the scalp. The Peptide + Ectoin Scalp Serum pairs a peptide blend with ectoin and niacinamide for a comfortable, conditioned scalp.
  4. Lashes and brows: a conditioning serum such as the Peptide Lash + Brow Conditioner keeps them looking soft and groomed.

Habits that help hair look its best

  • Be gentle: avoid tight hairstyles, aggressive brushing of wet hair, and very high heat.
  • Eat enough protein, iron and overall calories. Crash diets are a common trigger for temporary shedding.
  • Manage stress and sleep where you can. A major stressor can cause a wave of shedding two to three months later.
  • Give any scalp product at least three months; a hair cycle takes time.

When to see a dermatologist

See a board-certified dermatologist if you notice:

  • Sudden or heavy shedding, or hair coming out in clumps
  • Round bald patches, or hair loss in a new pattern
  • A red, scaly, itchy or painful scalp
  • Hair loss alongside other symptoms such as fatigue or weight change

FDA-approved treatments exist for pattern hair loss, and early diagnosis makes a real difference.

Frequently asked questions

Do peptides help hair growth?

Some peptides have shown promising effects on hair follicles in lab and animal studies, and one small human trial found an acetyl tetrapeptide-3 combination performed similarly to 3% minoxidil over 24 weeks. Overall, the evidence is early, and topical peptide products should be seen as scalp and hair care rather than a proven hair-growth treatment.

Are copper peptides good for hair?

Copper peptides have stimulated hair follicles in lab and animal research, which makes them an interesting scalp-care ingredient. However, we could not find a published, placebo-controlled human trial showing topical GHK-Cu grows hair.

What is the best peptide for hair loss?

Acetyl tetrapeptide-3, usually combined with red clover extract, has the most relevant human data, from a small 24-week randomized trial. No cosmetic peptide is a proven treatment for hair loss, so anyone with significant hair loss should see a dermatologist.

How long do hair peptides take to work?

Hair studies typically run 12 to 24 weeks because of the hair growth cycle. Give any scalp product at least three months of consistent use before judging it.

Can I use a peptide scalp serum with minoxidil?

Many people use cosmetic scalp serums alongside other treatments, but ask your dermatologist first, especially if you use a prescription product, so they can advise on timing and tolerance.

Do peptides work for eyelashes?

Lash serums with peptides are popular. One open-label study of a peptide lash serum reported longer, fuller-looking lashes after 12 weeks, but there was no control group. Myristoyl pentapeptide-17 itself doesn't yet have peer-reviewed data.

Sources

  1. Uno H, Kurata S. Chemical agents and peptides affect hair growth. J Invest Dermatol. 1993;101(1 Suppl):143S-147S. https://pubmed.ncbi.nlm.nih.gov/8326148/
  2. Trachy RE, Fors TD, Pickart L, Uno H. The hair follicle-stimulating properties of peptide copper complexes. Results in C3H mice. Ann N Y Acad Sci. 1991;642:468-469. https://pubmed.ncbi.nlm.nih.gov/1809108/
  3. Pyo HK, et al. The effect of tripeptide-copper complex on human hair growth in vitro. Arch Pharm Res. 2007;30(7):834-839. https://pubmed.ncbi.nlm.nih.gov/17703734/
  4. Pickart L. The human tri-peptide GHK and tissue remodeling. J Biomater Sci Polym Ed. 2008;19(8):969-988. https://pubmed.ncbi.nlm.nih.gov/18644225/
  5. Pickart L, Margolina A. Regenerative and Protective Actions of the GHK-Cu Peptide in the Light of the New Gene Data. Int J Mol Sci. 2018;19(7):1987. https://pubmed.ncbi.nlm.nih.gov/29986520/
  6. Lueangarun S, Panchaprateep R. An Herbal Extract Combination (Biochanin A, Acetyl tetrapeptide-3, and Ginseng Extracts) versus 3% Minoxidil Solution for the Treatment of Androgenetic Alopecia: A 24-week, Prospective, Randomized, Triple-blind, Controlled Trial. J Clin Aesthet Dermatol. 2020;13(10):32-37. https://pubmed.ncbi.nlm.nih.gov/33584955/
  7. Samadi A, et al. Assessment of the efficacy and tolerability of a topical formulation containing caffeine and Procapil 3% for improvement of male pattern hair loss. J Cosmet Dermatol. 2024;23(4):1492-1494. https://pubmed.ncbi.nlm.nih.gov/37990760/
  8. Fernandez-Gonzalez P, Truchuelo-Díez MT, Gómez-Sánchez MJ. Open clinical trial evaluating the efficacy of a novel eyelash growth enhancer with peptides and glycosaminoglycans. J Cosmet Dermatol. 2024;23(6):2170-2180. https://pubmed.ncbi.nlm.nih.gov/38572527/
  9. Bikash C. Topical Alternatives for Hair Loss: Beyond the Conventional. Int J Trichology. 2025;17(1):13-19. https://pubmed.ncbi.nlm.nih.gov/40654553/
  10. Pan X, et al. Technological Advances in Anti-hair Loss and Hair Regrowth Cosmeceuticals. Aesthetic Plast Surg. 2025;49(19):5341-5390. https://pubmed.ncbi.nlm.nih.gov/40790388/