Best Peptides for Hair Growth: GHK-Cu, PTD-DBM, Topical vs Injectable - Evidence Ranking

Key takeaways

• No peptide has an adequately powered human trial for hair growth. The best peptide data are small: an 18-person eyebrow study of a 2 percent GHK-Cu serum, a 45-man scalp trial of a copper-free GHK compound, and a 22-man trial of a cosmetic pentapeptide. PTD-DBM, thymosin beta-4 and TB-500 have no human hair study of their own, only mouse, rat and cell work.
• The treatments with real evidence are not peptides: topical minoxidil 5 percent (48-week trials in 393 men and 381 women) and, for men, finasteride 1 mg (1,553 men, two years). Low-dose oral minoxidil, a prescription off-label option, matched the topical in a 90-man randomized trial.
• Our ranking: topical copper peptides first and other cosmetic hair peptides second, both grade C and close to tied; PTD-DBM third and thymosin beta-4 or TB-500 fourth, both grade D. None comes near the benchmarks.
• Injectable 'hair peptides' (GHK-Cu shots, GLOW or KLOW vials, TB-500, PTD-DBM) have no controlled human study and no legal source: no US pharmacy may compound any of them as of October 2026. Scalp injections from unlabeled vials add infection risk, and GHK-Cu adds copper delivered past the gut.
• If you are losing hair, find the cause first, start minoxidil (and, for men, ask about finasteride), and judge the result at six to twelve months. A peptide serum is an optional cosmetic add-on, not a treatment.

Searching for a peptide for hair growth leads to copper peptide serums, 'hair density' multi-peptide bottles, a Korean laboratory peptide called PTD-DBM, and vials sold for injection into the scalp. This guide ranks them by what PubMed actually contains and sets them against the drugs that have large trials. The short answer: no peptide has been shown to regrow scalp hair in an adequately powered human trial, and the injectable versions have no controlled human evidence and no legal source. Copper peptides for hair loss goes deeper on serums versus injections, GHK-Cu dosage lists the concentrations that were studied, and the GHK-Cu profile has the full evidence table, the copper arithmetic and the legal history.

How we ranked

Four criteria, in order: human evidence for hair growth, graded A to D under our editorial policy; US legal status as of October 2026; safety; and cost. Popularity, photos and supplier data we could not read did not count. We searched PubMed and ClinicalTrials.gov for every candidate on October 10, 2026 and graded each by its best human hair study; when that study was on eyebrows, or tested a related molecule, we graded it down. Because pattern hair loss is progressive, a weak product costs months of untreated loss as well as money, so the drugs with large trials come first and each peptide faces one question: is there a reason to use it instead of, or alongside, minoxidil?

The ranking

Grades describe the evidence for hair growth only. The gap between the benchmark rows and rank 1 is the main finding of this guide.

The benchmark: what works for pattern hair loss

Topical minoxidil. In a 48-week double-blind trial, 393 men aged 18 to 49 applied 5 percent minoxidil, 2 percent minoxidil or placebo twice daily. The 5 percent solution beat both on hair counts and on patient and investigator ratings, produced 45 percent more regrowth than the 2 percent solution at week 48, and worked sooner; itching and local irritation were more common at the higher strength, with no systemic effects (Olsen 2002). The matching trial in 381 women with female pattern hair loss found 5 percent superior to placebo on all three primary measures, with more itching, irritation and unwanted hair growth than at 2 percent (Lucky 2004). Minoxidil slows loss and regrows some hair, mostly where thinning is recent; it does not restore a bald scalp, and the benefit fades when it is stopped.

Finasteride, for men. In two one-year trials of 1,553 men aged 18 to 41, with 1,215 continuing blinded for a second year, finasteride 1 mg a day increased hair counts in a one-inch circle of balding crown by 107 hairs over placebo at one year and 138 at two years, from a baseline of 876, while the placebo group kept losing hair (Kaufman 1998). The label limits it to men, contraindicates it in pregnancy, and warns that women who are or may become pregnant should not handle crushed or broken tablets. In the hair-loss trials, decreased libido (1.8 versus 1.3 percent), erectile dysfunction (1.3 versus 0.7 percent) and ejaculation disorder (1.2 versus 0.7 percent) were more common than on placebo, and postmarketing reports include depression, suicidal thoughts and sexual problems that continued after stopping (Propecia label).

Low-dose oral minoxidil. Interest has grown in prescribing minoxidil tablets at a fraction of the blood-pressure dose. The best comparative trial randomized 90 men to 5 mg daily by mouth or 5 percent topical twice daily, each with a matching placebo, for 24 weeks; 68 finished. The tablet was not superior on terminal hair density (frontal difference 3.1 hairs per square centimeter, P = .27; crown 23.4, P = .09), although photographic assessment favored it at the crown; 49 percent of the oral group grew unwanted body or facial hair and 14 percent had headaches (Penha 2024). The tablet is FDA-approved only for severe high blood pressure, and its label carries a boxed warning about fluid around the heart and worsening angina (minoxidil tablet label). It is an option for someone who cannot use the topical, prescribed by a clinician who checks heart history and blood pressure.

1. Copper peptides (GHK-Cu and relatives): mostly indirect evidence

GHK-Cu, a three-amino-acid peptide carrying a copper ion, is the most searched hair peptide in the US and the ingredient listed as copper tripeptide-1 on serums. Its hair story is built from four kinds of evidence, and only one tests GHK-Cu on its own in people.

• Animals and a cousin molecule. In a 1993 report, a copper-binding peptide coded PC1031 enlarged hair follicles on the backs of fuzzy rats, an effect the authors compared with topical minoxidil (Uno 1993). In 2007 a Seoul National University group showed that AHK-Cu, a cousin of GHK-Cu with alanine in place of glycine, lengthened human hair follicles kept alive in culture and multiplied dermal papilla cells at picomolar to nanomolar concentrations (Pyo 2007).
• One eyebrow study. In 2026, 18 healthy adults aged 18 to 40 applied a 2 percent GHK-Cu serum to one eyebrow and a placebo serum to the other, twice daily for 12 weeks, in a randomized, double-blind design. Hair count and hair diameter improved on the treated side, with no serious side effects or allergic reactions (Bo 2026). It appeared as a conference poster abstract, not in a PubMed-indexed journal, and the independent 2026 evidence map that found it notes it did not establish what form of the copper complex reached the skin or how much (Mateescu 2026).
• A scalp trial without copper. The only randomized scalp trial of a GHK-based product in pattern hair loss used a molecule that joins 5-aminolevulinic acid to copper-free GHK. Forty-five men sprayed it on the scalp nightly at 50 or 100 mg/mL, or used placebo, for six months; hair counts in a 1-cm circle rose by 71.5 and 52.6 hairs versus 9.6 on placebo, only the lower strength separated from placebo on the ratio measure, and hair length and thickness did not change (Lee 2016). The stronger dose doing worse and the absence of any change in thickness are reasons for caution.
• Mixtures delivered into the scalp. The only scalp data involving a copper peptide itself come from two uncontrolled series in which it was mixed with other actives: seven men treated by tattoo machine with minoxidil and dutasteride, and an open-label series of scalp injections combining growth factors, thymosin beta-4 and copper tripeptide-1. Copper peptides for hair loss explains why neither can credit the copper peptide.

The 2026 evidence map insists that GHK-Cu, copper-free GHK, GHK-derived copper peptides and other copper peptides are different entities that cannot be treated as interchangeable, and concludes that GHK-Cu remains promising but unproven (Mateescu 2026). That is our grade: C.

Legal status and cost. Copper peptide serums are legal cosmetics as long as the label does not promise regrowth, which would be a drug claim; the GHK-Cu profile explains the line. Prices run from drugstore to prestige, and a higher percentage on the label has no dose-response data behind it; GHK-Cu dosage lists what was studied. Who it is for: someone already on minoxidil, or unable to use it, who wants a gentle add-on and accepts that the scalp effect is unknown.

2. Cosmetic hair peptides in multi-peptide serums

'Multi-peptide serum for hair density' is among the most searched phrases in this category. The bottles typically combine supplier blends that pair a peptide, often acetyl tetrapeptide-3 or biotinoyl tripeptide-1, with plant extracts, sometimes with copper tripeptide-1 or caffeine. We found no published controlled trial of any finished multi-peptide serum.

The cleanest ingredient trial isolated a single peptide: 22 Japanese men with pattern hair loss used a lotion with or without the pentapeptide Gly-Pro-Ile-Gly-Ser for four months, double-blind, and the peptide group gained a larger share of thick hairs (60 micrometers or more), lost fine vellus hairs and scored better on blinded photo grading. Some authors worked for a cosmetics company, and the abstract gives no effect sizes (Iwabuchi 2016). An independent 2025 review of popular hair-serum actives found mostly combined formulations tested in small samples, without comparison to standard treatment and with conflicts of interest, and suggested at most an add-on role (Bikash 2025).

Grade C: one small, sponsor-run trial per ingredient at best, and no replication. It ranks a step below copper peptides only because GHK-Cu has independent investigators and a longer cosmetic safety record; on scalp data the two are close to tied. Legal status and cost: cosmetics, drugstore to mid-range. Who it is for: the same person as rank 1.

3. PTD-DBM: interesting biology, no human data

PTD-DBM pairs a protein-transduction domain, which carries cargo into cells, with a Dishevelled-binding motif. It was designed by Kang-Yell Choi's group at Yonsei University to block CXXC5, a protein that sits on Dishevelled and brakes the Wnt/beta-catenin signal that hair follicles use to enter a growth phase. In the founding paper, CXXC5 was elevated in miniaturized follicles from balding human scalps, it suppressed human dermal papilla cells in culture, mice lacking it regrew hair faster, and the competitor peptide accelerated both hair regrowth and the formation of new follicles in healing wounds in mice (Lee 2017). The senior author also lists an affiliation with a biotechnology company.

That is the record. We found no human study of PTD-DBM in PubMed or ClinicalTrials.gov as of October 10, 2026; figures for human results on sales pages come without a publication or trial registration. Grade D. Legal status: not approved anywhere we could find; it has no USP monograph, is not part of an approved drug and is not on FDA's permitted bulk list, so no US pharmacy may compound it, and the vials sold online are research chemicals. Who it is for: nobody outside a trial, which does not yet exist.

4. Thymosin beta-4 and TB-500: rodents only

Thymosin beta-4 is a 43-amino-acid protein involved in cell migration and blood-vessel growth. At the US National Institutes of Health it stimulated hair growth in normal rats and mice and increased the migration and maturation of follicle stem-cell-like keratinocytes in culture (Philp 2004). No human hair study of thymosin beta-4 on its own exists; it was one of six ingredients in the uncontrolled injection series described on the copper peptide page. What is sold as TB-500 is usually a seven-amino-acid fragment of the protein, not the protein, and it has never been tested for hair in animals or people; our TB-500 profile covers what is in the vials.

Grade D. Legal status: TB-500 cannot be compounded by any US pharmacy as of October 2026; FDA's advisory committee voted 8 to 6 in July 2026 to recommend it despite FDA reviewers noting no human studies, and nothing changes until FDA completes rulemaking. It is prohibited in sport at all times. Who it is for: nobody, for hair.

Injectable 'hair peptides': no controlled evidence and no legal source

The injectable side of the market sells GHK-Cu vials, GLOW and KLOW blends that add BPC-157 and TB-500, TB-500 alone, PTD-DBM, and scalp 'mesotherapy' cocktails. None has a controlled human study for hair. The one published series of scalp injections that included copper tripeptide-1 and thymosin beta-4 mixed them with four growth factors and had no control group; copper peptides for hair loss covers it. None has a legal US source either: no US pharmacy may compound injectable GHK-Cu, TB-500, BPC-157 or PTD-DBM as of October 2026, and FDA told five online vendors in August 2026 that research-use labels do not protect products sold with dosing instructions; see the legal tracker and the GLOW and KLOW review.

The risks are concrete even though nobody has counted them. An unlabeled vial has no verified content, sterility or endotoxin testing, and a needle in the scalp is a route for bacteria; the copper peptide page describes a published case of scalp mesotherapy that ended in abscesses and surgery. Immune reactions to peptide impurities were FDA's reason for flagging injectable GHK-Cu in 2023. And GHK-Cu is about 16 percent copper by weight: a 2 mg injection carries roughly 0.3 mg of copper, a 50 mg vial about 8 mg, delivered past the gut, where the body normally limits copper uptake; GHK-Cu injection versus topical has the detail.

What we excluded and why

• Collagen peptide supplements. A food supplement rather than a peptide therapy; outside the scope of this guide.
• Platelet-rich plasma, exosomes and growth factors. Not peptides; their evidence is a separate question.
• BPC-157 and KPV. No hair data in animals or humans that we could find, and neither is compoundable; see the BPC-157 and KPV profiles.
• Patchy hair loss. Alopecia areata is an autoimmune disease with its own prescription treatments; it needs a dermatologist, not a serum.

How to get it

1. Find the cause first. Thyroid disease, low iron, recent illness, childbirth, crash dieting and some medications thin hair, and several are reversible; a dermatologist or primary care clinician can sort them from pattern hair loss. Peptides for women covers the female-specific causes.
2. Start minoxidil. It is over the counter; follow the label and take photographs.
3. For men, ask about finasteride. It needs a prescription from a dermatologist, a primary care clinician or a telehealth service licensed in your state; consultations in our cost guide run from $0 to $200. Low-dose oral minoxidil is a prescriber's decision.
4. If you want a peptide serum, buy it as a cosmetic. Read the ingredient list, add one product at a time, and judge it after several months with the same camera, light and angle.
5. Do not buy injections for hair. No pharmacy can legally supply them and no study supports them.

Bottom line

The best peptide for hair growth, on the evidence, is a topical copper peptide or a cosmetic hair peptide serum, and both are grade C: an 18-person eyebrow study, a 45-man scalp trial of a copper-free cousin, a 22-man sponsor trial, and a lot of mice. PTD-DBM and thymosin beta-4 are animal stories. The injectable versions have no controlled human evidence, no legal source and real risks. Meanwhile minoxidil has 48-week trials in men and women and finasteride a two-year trial in more than 1,500 men. Start there, judge at six to twelve months, and treat any peptide as an optional extra.

Frequently asked questions

+−What peptides are good for hair?

None has been proved to regrow scalp hair in an adequately powered human trial. The closest are small studies: a 2 percent GHK-Cu (copper peptide) serum increased eyebrow hair count and thickness in 18 adults over 12 weeks; a copper-free GHK compound raised hair counts in 45 men over six months; a cosmetic pentapeptide increased the share of thick hairs in 22 men over four months. PTD-DBM and thymosin beta-4 have only animal and cell data. Topical minoxidil and, for men, finasteride have the large trials, so they come first.

+−What is the best peptide for hair growth?

By the evidence, a topical copper peptide (GHK-Cu, listed as copper tripeptide-1) is marginally ahead of the other cosmetic hair peptides, and both are grade C: small, short studies, mostly on eyebrows or in combination products. That makes the best peptide a cosmetic add-on rather than a treatment. If the goal is to keep or regrow scalp hair, minoxidil 5 percent and, for men, finasteride 1 mg have 48-week and two-year randomized trials, which no peptide has.

+−Does GHK-Cu injection help with hair?

There is no evidence that it does. No human study has tested injected GHK-Cu on its own, for hair or anything else. The only human hair result for GHK-Cu is a topical eyebrow study, and the only scalp data involving a copper peptide come from two uncontrolled series that mixed it with minoxidil and dutasteride or with growth factors, so the copper peptide's contribution is unknown. Injectable GHK-Cu cannot be compounded by any US pharmacy as of October 2026, and a 2 mg dose carries about 0.3 mg of copper past the gut, which normally limits copper uptake.

+−Do multi-peptide hair density serums work?

Nobody has shown it. We found no published controlled trial of any finished multi-peptide hair serum. The ingredients inside them are supplier blends that pair a peptide with plant extracts, each tested, if at all, in a single small study run or funded by the company that sells it. A 2025 independent review of these hair actives found small samples, no comparison with standard treatment and conflicts of interest, and suggested at most an add-on role. Use one if you like it, alongside minoxidil, not instead of it.

+−What is PTD-DBM, and does it regrow hair?

PTD-DBM is a lab peptide from a Korean university group that blocks CXXC5, a protein that brakes the Wnt signal hair follicles use to regrow. CXXC5 is raised in miniaturized follicles from balding human scalps, and the peptide sped hair regrowth in mice. That is the whole record: no human study appears in PubMed or ClinicalTrials.gov as of October 2026. It is not approved anywhere we know of, no US pharmacy may compound it, and vials sold online are research chemicals.

+−Does TB-500 help hair growth?

Not in any study of people. Full-length thymosin beta-4, the 43-amino-acid protein TB-500 is cut from, stimulated hair growth in rats and mice in a 2004 NIH study. TB-500 itself, a seven-amino-acid fragment, has never been tested for hair in animals or humans. It cannot be compounded by any US pharmacy as of October 2026, an FDA advisory vote in July 2026 changed nothing until FDA acts, and it is banned in sport.

+−What's the downside of taking peptides for hair?

For topical cosmetic peptides, mainly cost and lost time: they are gentle, with irritation and copper contact allergy the documented problems, but months on an unproven serum are months of untreated pattern hair loss, which is progressive. For injected peptides the downsides are larger and unmeasured: no proof of benefit, no quality control, infection risk from unsterile vials injected into the scalp, immune reactions to impurities, and with GHK-Cu, copper delivered past the gut. None of the injectables has a legal US source.

+−How do you stop hair loss from Hashimoto's?

Treat the thyroid. Hair shedding from an underactive or overactive thyroid usually improves once hormone levels are back in range, which can take months, and the American Academy of Dermatology notes that treating thyroid disease can reverse the hair loss. Ask your clinician to check iron stores too, because low iron is common and also thins hair. No peptide addresses thyroid-related hair loss; if thinning continues after the thyroid is controlled, pattern hair loss may be developing alongside it, and minoxidil is the evidence-based start.

Sources

1. StudyOlsen 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;47:377-85. (2002)
2. StudyLucky AW et al. A randomized, placebo-controlled trial of 5% and 2% topical minoxidil solutions in the treatment of female pattern hair loss. J Am Acad Dermatol 2004;50:541-53. (2004)
3. StudyKaufman KD et al. Finasteride in the treatment of men with androgenetic alopecia. Finasteride Male Pattern Hair Loss Study Group. J Am Acad Dermatol 1998;39:578-89. (1998)
4. LabelDailyMed. Propecia (finasteride 1 mg) prescribing information, published October 14, 2024: men only; contraindicated in pregnancy; decreased libido, erectile dysfunction and ejaculation disorder versus placebo; postmarketing reports of depression, suicidal ideation and sexual dysfunction continuing after discontinuation. (2024)
5. StudyPenha MA, Miot HA, Kasprzak M, Muller Ramos P. Oral minoxidil vs topical minoxidil for male androgenetic alopecia: a randomized clinical trial. JAMA Dermatol 2024;160:600-605. (2024)
6. LabelDailyMed. Minoxidil tablets prescribing information (generic), published August 31, 2026: indicated only for severe hypertension not controlled by a diuretic plus two other drugs; boxed warning for pericardial effusion progressing to tamponade and worsening angina. (2026)
7. ReviewMateescu DM et al. GHK-Cu as a bioactive metallopeptide and drug-delivery cargo: coordination chemistry, formulation science, therapeutic evidence, and a translational roadmap (systematic evidence-mapping review). Pharmaceutics 2026;18:1077. (2026)
8. StudyBo SL, Nararatwanchai T, Supornpun N, Poomarapan K, Thaploka S. The efficacy of 2% copper peptide (GHK-Cu) serum for eyebrow hypotrichosis: a randomized, double-blind, vehicle-controlled, split-face comparative study. Procedia of Multidisciplinary Research 2026;4(5). Conference poster abstract; not indexed in PubMed. (2026)
9. StudyLee WJ et al. Efficacy of a complex of 5-aminolevulinic acid and glycyl-histidyl-lysine peptide on hair growth. Ann Dermatol 2016;28:438-43. (Copper-free GHK conjugate.) (2016)
10. StudyUno H, Kurata S. Chemical agents and peptides affect hair growth. J Invest Dermatol 1993;101(1 Suppl):143S-147S. (1993)
11. StudyPyo HK et al. The effect of tripeptide-copper complex on human hair growth in vitro. Arch Pharm Res 2007;30:834-9. (Tested AHK-Cu, a related copper tripeptide.) (2007)
12. StudyLee SH, Seo SH, Lee DH, Pi LQ, Lee WS, Choi KY. Targeting of CXXC5 by a competing peptide stimulates hair regrowth and wound-induced hair neogenesis. J Invest Dermatol 2017;137:2260-2269. (2017)
13. StudyPhilp D et al. Thymosin beta4 increases hair growth by activation of hair follicle stem cells. FASEB J 2004;18:385-7. (2004)
14. StudyIwabuchi 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;15:176-84. (Authors include employees of a cosmetics company.) (2016)
15. ReviewBikash C. Topical alternatives for hair loss: beyond the conventional. Int J Trichology 2025;17:13-19. (2025)