Peptides for Hair Growth: What the Trials Actually Show (2026)

Open any "peptides for hair growth" page and you get the same list: copper peptides, biotinoyl tripeptide-1, acetyl tetrapeptide-3, a few things sold in vials. What you do not get is what a dermatology journal would insist on — how many people were in the trial, whether there was a placebo, and who paid. We opened the studies cited below and say so wherever a source could not be traced. The placebo-controlled trials of defined hair peptides enrolled 22 to 45 people over four to six months, nearly all run or written by the ingredient's manufacturer; the one randomized comparison against minoxidil in an indexed journal had 32 participants and no placebo arm; no peptide has a placebo-controlled trial showing it beats minoxidil or finasteride; the vial-form "research" peptides have animal data and one uncontrolled cocktail pilot, nothing that isolates them in humans. That is not nothing, but it is a long way from how these ingredients are sold.

How we tiered the evidence

Criteria reviewed 2026-09-05. Every peptide gets one of six tiers, based on the best study we could open and read, not on how many blogs cite it:

• Human RCT — randomized, with a placebo or active comparator, peer-reviewed.
• Manufacturer trial, unpublished — randomized and placebo-controlled but never peer-reviewed; ranked below any published RCT.
• Human open-label or uncontrolled — treated and measured, no control group, so nothing can be attributed to one ingredient.
• Animal — rats or mice, usually with shaved dorsal skin; a 2026 review in Biomedicines notes that shaving mouse hair "does not accurately replicate any disease".
• In vitro / ex vivo — cells or plucked follicles in a dish.
• None — no published hair data we could locate.

The funding column matters because it changes how a number should be read: "manufacturer-authored" means the authors worked for the company selling the ingredient, and we never write "industry-funded" unless a funding line says so. Our testing notes explain how we handle ingredient claims; this page carries no product picks.

The evidence table

Copper peptides (GHK-Cu) for hair

What the lab studies show

The most-cited paper is from Seoul National University's dermatology department, and it did not test GHK-Cu. Pyo and colleagues (2007) tested AHK-Cu — alanyl-histidyl-lysine copper, a different tripeptide — and found it stimulated the elongation of human hair follicles ex vivo and the proliferation of dermal papilla cells in vitro; the reduction in apoptotic dermal papilla cells "was not statistically significant." A dish result on a cousin molecule is what most "GHK-Cu regrows hair" claims trace back to.

The animal data are older. In 1993, Uno and Kurata of the Wisconsin Regional Primate Research Center reported that a copper-binding peptide, PC1031, enlarged follicles on the back skin of fuzzy rats, "similar to that of topical minoxidil." A 1991 abstract on peptide copper complexes in C3H mice (PMID 1809108) lists its authors at ProCyte Corporation, the company then developing copper peptides.

Who wrote the reviews

The paper that says GHK-Cu increases "hair follicle size" and "improves hair transplant success" is a 2008 review by Loren Pickart, its sole author, whose listed affiliation is Skin Biology — a company selling GHK-Cu products; a 2015 review by Pickart and colleagues from the same company's R&D department adds wound healing of hair follicles. That does not make them wrong, but a company review is not a trial.

The one human trial, and it is not GHK-Cu

The 2026 Biomedicines review supports GHK-Cu's human hair effect with a single citation, "a clinical study of 45 AGA patients." We opened it, and it is not a GHK-Cu trial. Lee and colleagues (2016), in Annals of Dermatology, randomized 45 Korean men with pattern hair loss, double-blind, to a spray combining 5-aminolevulinic acid with GHK peptide — described in the paper as copper-free — at two strengths or placebo for six months. Hair count rose 52.6 and 71.5 versus 9.6 on placebo; only the lower-strength arm differed significantly from placebo, hair length and thickness did not differ, and the authors (Kyungpook National University, supported by a regional Korean small-business agency) call it a possible complementary agent. Because the peptide was paired with 5-ALA rather than copper, nothing in it can be attributed to GHK-Cu, and it is not evidence for GHK-Cu serums. For GHK-Cu itself there is still no published placebo-controlled human hair trial, and vial-form research GHK-Cu has no human hair trial on its own.

GHK-Cu's skin literature is larger and better than its hair literature, which is why marketing conflates the two. The skin side is in our copper peptides guide; this page stays on hair.

Biotinoyl tripeptide-1 (Procapil)

The 2004 Sederma dossier, unpublished

Procapil is Sederma's complex of biotinoyl tripeptide-1 with apigenin and oleanolic acid. Its only placebo-controlled trial of Procapil on its own sits in a Sederma technical dossier dated March 2004, run by the contract laboratory Laboratoires DERMSCAN (hair samples analyzed by BIO-EC) and never published in a journal. Thirty-five Caucasian men aged 18 to 50 were randomized to a 3% Procapil lotion (18) or placebo (17) for four months. The dossier reports that 67% of the Procapil group — 12 of 18 — improved their anagen/telogen ratio, and that mean hair growth rate "showed no significant difference." Its significance test is against baseline (+10% anagen hairs, p<0.05); of the placebo it says only that "the placebo is inactive."

What "comparable to finasteride" actually means

The dossier's finasteride comparison is against published finasteride literature, not a finasteride arm in the same trial. A 12-of-18 result in an unpublished manufacturer file, with a non-significant growth-rate outcome, is the whole clinical case for Procapil alone, and the dossier trial itself has never been through peer review. Procapil has since appeared in peer-reviewed trials, always inside a combination: a 2023 randomized trial in Cureus (Pavithra and colleagues, 54 men, six months, academic authors, no competing interests declared) paired it with platelet-rich plasma in both arms and found the Redensyl–saw palmetto–biotin comparator did better; a 2019 randomized comparison in a non-indexed journal (Karaca and Akpolat) scored a Redensyl–Capixyl–Procapil spray above 5% minoxidil on photographs in 106 men over 24 weeks, with no placebo and no funding statement. None of them can isolate the peptide.

Acetyl tetrapeptide-3 (Capixyl)

Capixyl is the best-evidenced cosmetic hair peptide, which says as much about the field as about Capixyl.

The manufacturer trial

Loing and colleagues (2013), writing from the R&D department of Lucas Meyer Cosmetics, ran a randomized, placebo-controlled study in 30 volunteers with receding hair over four months. By TrichoScan, anagen hair rose 13% and telogen density fell 29% in the treated group, with the anagen/telogen ratio up 46%; the placebo group went the other way (anagen −2%, telogen +23%, ratio −33%). Search snippets circulate different figures; these are from the published abstract.

The PubMed-indexed trial against minoxidil

Lueangarun and Panchaprateep (2020) is the only randomized hair-peptide trial on this page carrying "no funding was provided for this study," and the only comparison against minoxidil in a PubMed-indexed journal. Thirty-two adults with mild to moderate androgenetic alopecia were assigned, triple-blind, to an acetyl tetrapeptide-3 + biochanin A + ginseng combination or a 3% minoxidil solution for 24 weeks. Terminal hair count rose 8.3% and 8.7% respectively, with no significant difference; one minoxidil user developed scalp eczema. Two limits: no placebo arm, so "as good as" could also mean "both did little," and a 3% minoxidil comparator, below the 5% strength sold over the counter in the US. The 2019 Turkish spray comparison above shares the first limit and adds a non-indexed venue.

What the trichology review says

A 2025 review in the International Journal of Trichology of Redensyl, Procapil, Capixyl and similar actives found most of their studies "have limited sample size, lack of comparison with standard therapies", nonuniform groups, undisclosed alopecia type, "and conflicts of interest." The author declared none.

"Peptide" shampoos, serums and supplements

GPIGS: the Shiseido pentapeptide

Iwabuchi and colleagues (2016) tested a lotion containing the pentapeptide Gly-Pro-Ile-Gly-Ser in 22 Japanese men with androgenetic alopecia for four months, double-blind and randomized. The proportion of thick hair (60 µm or more) rose versus placebo (P=0.006), vellus hair fell (P=0.029), and blinded photo grading improved (P=0.020). The author list is led by Shiseido's Global Innovation Center.

The "peptide serum" trial that cannot isolate a peptide

A 2025 trial in the Journal of Cutaneous and Aesthetic Surgery comparing "hair peptide serums" in 45 women with telogen effluvium (14 per group after dropouts, 90 days, open-label) actually compared three multi-ingredient serums, two of which carry the very peptides on this list: the plant-stem-cell serum includes biotinoyl tripeptide-1 with apigenin and oleanolic acid (Procapil's trio); the growth-factor serum includes acetyl tetrapeptide-3 with red clover extract (Capixyl's pair) and was, per the paper, "researched and developed by Palsons Derma Pvt. Ltd."; the third is Redensyl plus aminexil. Shedding fell 23.9%, 54.6% and 26.3%, with no untreated control and a dozen or more actives per bottle, so nothing can be attributed to a peptide. Sponsorship is declared as nil; one co-author is affiliated with Palsons Derma. For oligopeptide shampoos, we found no peer-reviewed human trial, so that table row is empty rather than invented.

Egg-yolk peptides, and a peptide studied for graying

Nakamura and colleagues (2018) report that water-soluble chicken egg yolk peptides stimulated VEGF and dermal papilla cell growth, enhanced murine hair growth and, in the authors' words, "improve hair growth in FPHL." The first author and four co-authors work for Pharma Foods International, the manufacturer; the other three are at Charle Co., Hallym University and Osaka University. Per the 2026 review's summary of the paper, the human arm was a 76-subject, 24-week placebo-controlled study — figures we could not open the full text to confirm. Palmitoyl tetrapeptide-20, which consumer lists call a hair-growth "signal peptide," was studied for graying, not growth: the published study, from IFF-Lucas Meyer Cosmetics and Ales Groupe, enrolled 15 men with premature graying for three months and measured pigmentation markers.

The mass-market example

The product most answers name is The Ordinary's Multi-Peptide Serum for Hair Density. Its product page discloses caffeine, biotinoyl tripeptide-1, acetyl tetrapeptide-3, Redensyl, AnaGain, Procapil, Capixyl and Baicapil among its actives — most of this page in one bottle, which is why no trial above can be read across to it. We found no published trial of the finished product, and the page cites none. Products named on this page are formulation examples; nothing here is ranked, scored or affiliate-linked.

Thymosin beta-4 (TB-500): animal evidence, plus one uncontrolled cocktail pilot

Thymosin beta-4's hair data come from NIH. Philp and colleagues (2004) reported that it "stimulates hair growth in normal rats and mice," acting on bulge stem-cell migration; a 2007 follow-up (PMID 17947589) reconfirmed this in a transgenic mouse. There is no human hair trial of thymosin beta-4 alone in PubMed.

The only human data that include it come from a 1,000-patient open-label, single-arm pilot at a Mumbai clinic of a six-ingredient growth-factor cocktail — VEGF, bFGF, IGF, KGF, thymosin beta-4 and copper tripeptide-1 — in which 83% of patients showed reduced hair fall on a pull test. With no control group and six actives, nothing can be attributed to thymosin beta-4 or the copper peptide. This is research context, not a use case.

PTD-DBM and other research-only compounds

PTD-DBM is a peptide designed to block the CXXC5–Dishevelled interaction, releasing the Wnt/beta-catenin pathway follicles depend on. In Lee and colleagues (2017) it accelerated hair regrowth and wound-induced follicle neogenesis in mice; CXXC5 was also found upregulated in miniaturized follicles from balding human scalps. The affiliations include CK Biotechnology Inc.; a 2021 paper from the same lab on a different Wnt activator, the small molecule KY19382 (PMID 33751552), discloses the senior author as CEO of CK Biotech, which licenses the compounds in that paper, while the 2017 PTD-DBM paper carries no such disclosure. Mouse data, company-affiliated authors, no human trial.

PP405 belongs here because it is often listed among hair peptides — including by the 2026 Biomedicines review — but Pelage Pharmaceuticals' own release calls it "a novel, non-invasive, topical small molecule". Its Phase 2a trial enrolled 78 men and women with androgenetic alopecia; at week 8, 31% of treated men with a higher degree of hair loss showed more than a 20% increase in hair density, versus 0% on placebo. Those are press-release figures, not yet a published paper, and it is not a peptide.

The benchmarks readers compare against

Minoxidil and finasteride appear here as evidence context — the scale a "works for hair" claim is measured against — not as recommendations.

Minoxidil

Olsen and colleagues (2002) randomized 393 men aged 18 to 49 to 5% minoxidil, 2% minoxidil or placebo for 48 weeks; 5% was superior to both on non-vellus hair count, with more itching and irritation. In women, the 2016 Cochrane review pooled 47 trials and 5,290 participants: minoxidil users were roughly twice as likely to report moderate-to-marked regrowth as placebo (RR 1.93), gained about 13 hairs per square centimeter more, and 2% and 5% did not differ. The OTC labels set the timelines: at least 4 months before some men see results on the men's 5% foam, and stop and ask a doctor after 6 months without regrowth on the women's 5% foam.

Finasteride

Kaufman and colleagues (1998) — first author at Merck Research Laboratories — enrolled 1,553 men aged 18 to 41 in two one-year trials of finasteride (Propecia) versus placebo. Hair count in a one-inch vertex circle (baseline 876 hairs) was 107 hairs higher than placebo at one year and 138 at two. The FDA label states the indication is for men only, that "daily use for three months or more is necessary before benefit is observed," that "withdrawal of treatment leads to reversal of effect within 12 months," that it is contraindicated in pregnancy, and that drug-related sexual adverse experiences in year one were 3.8% versus 2.1% on placebo.

Peptides for hair loss: what to expect from the evidence

Put the numbers side by side and the gap is the story. The largest placebo-controlled trial of a defined hair peptide we could open had 45 participants, and it tested a copper-free GHK complex; the Capixyl and GPIGS placebo trials had 30 and 22, the unpublished Procapil dossier 35; the larger trials on this page test cocktails or combinations that cannot isolate a peptide, and the one 1,000-patient study was an uncontrolled six-ingredient cocktail. The finasteride label trials had 1,553, the 5% minoxidil trial 393, the Cochrane minoxidil review 5,290. We found no systematic review of randomized peptide trials. The placebo-controlled peptide trials ran four months (Capixyl, GPIGS, the Procapil dossier) to six months (the GHK complex) — one to two telogen cycles — and the two comparisons against minoxidil ran 24 weeks; most measured hair counts, anagen/telogen ratios or thick-hair proportions by trichoscopy, not the visible change a before-and-after photo implies. A 13% rise in anagen hairs is a shift in a ratio, not a hairline moving.

The 2026 review says it most directly: the peptide clinical studies "do not provide meaningful comparisons with established drugs such as minoxidil or finasteride, which undermines their credibility." The exceptions are the 32-person trial above and the 2019 Turkish comparison, both without a placebo arm. So the honest expectation: a cosmetic peptide serum has small-trial evidence for nudging follicle ratios the right way over four months, mostly generated by the companies selling it; nothing here has placebo-controlled evidence of matching an approved drug; the vial end of the market has no human hair data of its own. Where a trend crosses into research-only compounds, we report the context and stop — a beauty publication, not an instruction manual, as our testing notes put it.

When to see a dermatologist

Hair loss is common and distressing, and it has several causes that call for different responses — so the first job is finding out which kind it is, and peptide serums do not diagnose. The American Academy of Dermatology says it is normal to shed between 50 and 100 hairs a day, that heavier shedding often follows a trigger such as childbirth, high fever, surgery, serious illness, significant weight loss or stopping birth control, and that postpartum shedding peaks around four months with fullness tending to return within six to nine months. See a dermatologist, it says, if you are unsure whether you are shedding or losing hair.

For women, the AAD notes that female pattern hair loss is the most common cause of hair loss in women, that minoxidil is the most-recommended treatment for it, that "treatment delivers the best results when started at the first sign of hair loss," and that other causes can look like it — so evaluation comes first.

The OTC minoxidil labels list situations they say not to self-treat, which doubles as a list of reasons to book an appointment: sudden or patchy loss, loss of unknown cause, no family history of hair loss, an inflamed or painful scalp, hair loss associated with childbirth (women's label), and anyone under 18. Those are label facts, not a diagnosis; a dermatologist can tell you which, if any, applies.

This article is evidence journalism, not medical advice. Evidence last checked 2026-09-05. Published by Peptide Glow Journal Editorial.

Sources

• Fan C et al. Overview of Short Peptides for Hair Loss. Biomedicines 2026;14(4):864. PMC13113319. Funding: IPIC HKUST Dream Builder and HKSTP Ideation Program; authors declare no conflicts. Its "45 AGA patients" citation is reference 18, Lee 2016 below.
• Lee WJ, Sim HB, Jang YH, Lee SJ, Kim DW, Yim SH. Efficacy of a Complex of 5-Aminolevulinic Acid and Glycyl-Histidyl-Lysine Peptide on Hair Growth. Ann Dermatol 2016;28(4):438-43. PMID 27489425, PMC4969472. Kyungpook National University and Dongshin University; supported by the Small and Medium Business Administration of Gwangju & Jeollanam-do; no conflict statement.
• Pyo HK et al. The effect of tripeptide-copper complex on human hair growth in vitro. Arch Pharm Res 2007;30(7):834-9. PMID 17703734.
• Uno H, Kurata S. Chemical agents and peptides affect hair growth. J Invest Dermatol 1993;101(1 Suppl):143S-147S. PMID 8326148. Trachy RE et al. Ann N Y Acad Sci 1991;642:468-9, PMID 1809108 (ProCyte Corporation).
• Pickart L. The human tri-peptide GHK and tissue remodeling. J Biomater Sci Polym Ed 2008;19(8):969-88. PMID 18644225 (Skin Biology; sole author). Pickart L, Vasquez-Soltero JM, Margolina A. Biomed Res Int 2015, PMID 26236730 (Skin Biology R&D).
• Sederma. Procapil: For enhanced anchorage of the hair — technical dossier, 03/2004/V1. PDF hosted by a hair clinic. Unpublished manufacturer document; clinical trial by Laboratoires DERMSCAN, hair analysis by BIO-EC.
• Pavithra et al. A Comparative Study of Topical Procapil With Platelet-Rich Plasma Therapy Versus Topical Redensyl, Saw Palmetto, and Biotin With Platelet-Rich Plasma Therapy in the Treatment of Androgenetic Alopecia. Cureus 2023 (published May 8, 2023). PMC10246929. Sri Devaraj Urs Academy of Higher Education and Research; no competing interests declared; no funding statement.
• Karaca N, Akpolat ND. A Comparative Study between Topical 5% Minoxidil and Topical "Redensyl, Capixyl, and Procapil" Combination in Men with Androgenetic Alopecia. J Cosmo Trichol 2019;5:140. PDF. Not PubMed-indexed; no funding statement; the paper says the spray was formulated at Yeditepe University and its rights are registered under the name Procare.
• Loing E et al. A new strategy to modulate alopecia using a combination of two specific and unique ingredients. J Cosmet Sci 2013;64(1):45-58. PMID 23449130 (Lucas Meyer Cosmetics R&D).
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• Iwabuchi T et al. The topical penta-peptide Gly-Pro-Ile-Gly-Ser increases the proportion of thick hair in Japanese men with androgenetic alopecia. J Cosmet Dermatol 2016;15(2):176-84. PMID 27030543 (Shiseido; co-authors at AIST, Frontier Technology Laboratory Inc. and Keiyu Hospital).
• Nakamura T et al. Naturally Occurring Hair Growth Peptide: Water-Soluble Chicken Egg Yolk Peptides. J Med Food 2018;21(7):701-708. PMID 29583066 (first author and four co-authors at Pharma Foods International; others at Charle Co., Hallym University and Osaka University).
• Almeida Scalvino S et al. Efficacy of an agonist of α-MSH, the palmitoyl tetrapeptide-20, in hair pigmentation. Int J Cosmet Sci 2018;40(5):516-524. PMID 30222197 (IFF-Lucas Meyer Cosmetics).
• Chandrashekar BS et al. Comparative analysis of various hair peptide serums in managing telogen effluvium in females. J Cutan Aesthet Surg 2025;18(4):278-285. Full text. Sponsorship declared nil; one co-author is affiliated with Palsons Derma, the developer of the growth-factor serum tested.
• The Ordinary. Multi-Peptide Serum for Hair Density, product page. theordinary.com. Retailer page; disclosed actives only; no trial cited.
• Philp D et al. Thymosin beta4 increases hair growth by activation of hair follicle stem cells. FASEB J 2004;18(2):385-7. PMID 14657002 (NIH/NIDCR). Philp D et al. Ann N Y Acad Sci 2007, PMID 17947589.
• Kapoor R, Shome D. Intradermal injections of a hair growth factor formulation: first-in-man pilot clinical study. J Cosmet Laser Ther 2018;20(6):369-379. PMID 29482481. Funding not stated; authors at the treating clinic.
• Lee SH et al. Targeting of CXXC5 by a Competing Peptide Stimulates Hair Regrowth and Wound-Induced Hair Neogenesis. J Invest Dermatol 2017;137(11):2260-2269. PMID 28595998. Ryu YC et al. KY19382. Br J Pharmacol 2021, PMID 33751552 (CEO/license disclosure covers the compounds in that paper).
• Pelage Pharmaceuticals. Positive Phase 2a results for PP405, press release, June 17 2025. Syndicated on Yahoo Finance. Company release.
• Olsen EA et al. A randomized clinical trial of 5% topical minoxidil versus 2% topical minoxidil and placebo in the treatment of androgenetic alopecia in men. J Am Acad Dermatol 2002;47(3):377-85. PMID 12196747.
• van Zuuren EJ, Fedorowicz Z, Schoones J. Interventions for female pattern hair loss. Cochrane Database Syst Rev 2016;(5):CD007628. PMID 27225981. No financial conflicts.
• Kaufman KD et al. Finasteride in the treatment of men with androgenetic alopecia. J Am Acad Dermatol 1998;39(4 Pt 1):578-89. PMID 9777765 (Merck Research Laboratories).
• PROPECIA (finasteride) prescribing information, revised 04/2012. FDA label PDF.
• Kirkland Signature Minoxidil 5% foam, Drug Facts. DailyMed.
• Women's Rogaine Unscented (minoxidil 5%) foam, Drug Facts. DailyMed.
• American Academy of Dermatology. Hair shedding often occurs after stress and Female pattern hair loss.