Copper Peptides for Hair: GHK-Cu and AHK-Cu, Evidence Graded

This page covers the two copper peptides only. For every peptide sold for hair, graded side by side, see peptides for hair growth; for the androgenetic alopecia angle, see peptides for hair loss. Research compounds are research use only, a finished cosmetic serum is an ordinary cosmetic, and nothing here is medical advice.

GHK-Cu and AHK-Cu are not the same molecule

Both are copper complexes of a three amino acid peptide ending in histidine and lysine. The only structural difference is the first residue, glycine in GHK and alanine in AHK. Many pages cite the AHK-Cu follicle experiment and the PC1031 rat study as if they were GHK-Cu results. Neither abstract says that.

The hair evidence, study by study

Pyo and colleagues (Arch Pharm Res 2007) tested AHK-Cu at 10^-12 to 10^-9 M. A follicle in a dish has no skin barrier, blood supply or androgen environment, so it shows what the molecule can do, not what a serum does. Uno and Kurata (J Invest Dermatol 1993) describe PC1031 as a copper-binding peptide; the abstract does not call it GHK-Cu. Lee and colleagues (Ann Dermatol 2016) tested a complex of 5-aminolevulinic acid and GHK, so the result cannot be credited to GHK-Cu alone. Bo and colleagues (Procedia of Multidisciplinary Research 2026) is the first randomised study of GHK-Cu serum on hair that the Bureau found; its abstract gives no numeric effect sizes, and eyebrow hair is not scalp hair. Kapoor and Shome (J Cosmet Laser Ther 2018) had no control arm and five other actives in the syringe.

On mechanism, the discoverer's reviews list increases in VEGF and FGF-2, among others, and increased hair follicle size (Pickart 2008); GHK declines with age (Pickart 2015). Maquart and colleagues reported collagen synthesis stimulated in fibroblast cultures (FEBS Lett 1988). These are cell-culture and review findings. The gap is not plausibility, it is that the trial has not been run. A 2026 review of GHK-Cu calls the clinical evidence sparse and describes the eyebrow study as positive but with chemically undercharacterised material (Mateescu 2026).

Bureau evidence grade

Serum percentages, as reported

Scalp solutions of 0.1 to 0.5 percent circulate in community use, against 1 to 2 percent for the face. Those are conventions, not trial doses; the only randomised strength found was 2% twice daily for 12 weeks on eyebrows. Mixing is arithmetic: percent is milligrams per millilitre divided by ten. The bac water guide covers the diluent and the storage guide how long a mixed bottle keeps.

DIY solutions against finished serums

A research solution in bacteriostatic water is peptide in water: no emollients, no penetration enhancer, no pH buffering and no stability testing. A finished serum is formulated, but it rarely states how much peptide it holds. Whichever you use, only a certificate of analysis that reports copper content shows a vial is GHK-Cu rather than under-coppered GHK; the testing guide covers what to ask for. Colour is a rough proxy, not a measurement.

Injected scalp protocols, as reported

Two practices circulate. Clinic mesotherapy places small amounts intradermally in a grid; the only human documentation is the uncontrolled cocktail series above. Subcutaneous injection is systemic, so no evidence says it reaches a follicle in a useful amount. The Bureau does not describe a home version of either. Amounts below are reported conventions, not recommendations.

GHK-Cu is about 16 percent copper by mass, so 2 mg carries roughly 0.3 mg of copper, a calculation and not a trial result. The GHK-Cu side effects page works through the copper arithmetic and the sting. The GHK-Cu guide covers mechanism, and the TB-500 guide covers the other peptide that turns up in scalp protocols.

Before and after photographs

Hair is hard to photograph consistently, and nearly every variable in a casual snapshot moves in the flattering direction. A real result is modest: a narrower part line or better coverage at the temples, judged against a baseline at the same distance, light and part position, with dry hair, at least twelve weeks apart. Copper peptides are not described in any study as reversing a slick scalp. The before and after guide covers how the Bureau reads result photographs, and top peptides for skin and hair places the copper peptides in the wider field.

For the vial arithmetic on a U-100 syringe, the Peptulator GHK-Cu calculator does the maths for any vial and water volume.

Frequently asked questions

Do copper peptides work for hair growth?

The evidence is low grade. AHK-Cu lengthened human hair follicles in culture and proliferated dermal papilla cells in vitro. A copper-binding peptide coded PC1031 enlarged follicles in fuzzy rats. The human trials are small: a 2026 split-face study of a 2% GHK-Cu serum on eyebrows (18 adults) found better hair count and diameter, and a 45-man trial of a 5-ALA plus GHK complex raised hair count. The Bureau found no trial of GHK-Cu alone on a scalp.

What is the difference between AHK-Cu and GHK-Cu?

One amino acid. GHK is glycyl-histidyl-lysine and AHK is alanyl-histidyl-lysine, so AHK carries one extra methyl group, about 14 daltons, and both bind copper at the histidine. The direct hair evidence, follicle elongation ex vivo, belongs to AHK-Cu. GHK-Cu has the wound trial, the wider skin literature and the eyebrow serum study.

What percentage of GHK-Cu is used on the scalp?

Scalp solutions of 0.1 to 0.5 percent are reported in community use, against 1 to 2 percent for the face. No trial has tested a scalp strength. The only randomised strength found was 2% twice daily on eyebrows for 12 weeks. Percent is milligrams per millilitre divided by ten, so 50 mg of powder in 50 mL of water is 0.1 percent and in 10 mL is 0.5 percent.

Are GHK-Cu hair growth before and after photos reliable?

Mostly not. Wet hair reads thinner than dry, overhead light exaggerates a part, and a shifted part line changes the visible scalp. A real result is modest, a narrower part line or better coverage at the temples, and needs two photographs at the same distance, in the same light, with dry hair parted in the same place, at least twelve weeks apart.

Is an AHK-Cu and GHK-Cu hair serum better than GHK-Cu alone?

Nobody has tested the pair against either one alone, so better is an inference. The case for pairing is that AHK-Cu has the follicle experiment and GHK-Cu has the wider human data. The case against is that a blend removes your ability to change one variable at a time, and the vehicle probably matters more than the pairing.

Sources

1. Pyo HK et al. The effect of tripeptide-copper complex on human hair growth in vitro. Arch Pharm Res 2007
2. Uno H, Kurata S. Chemical agents and peptides affect hair growth. J Invest Dermatol 1993
3. Lee WJ et al. Efficacy of a complex of 5-aminolevulinic acid and glycyl-histidyl-lysine peptide on hair growth. Ann Dermatol 2016
4. Bo et al. The Efficacy of 2% Copper Peptide (GHK-Cu) Serum for Eyebrow Hypotrichosis. Procedia of Multidisciplinary Research 2026
5. Kapoor R, Shome D. Intradermal injections of a hair growth factor formulation: first-in-man pilot study. J Cosmet Laser Ther 2018
6. Mateescu DM et al. GHK-Cu as a bioactive metallopeptide and drug-delivery cargo. Pharmaceutics, 27 Aug 2026
7. Pickart L. The human tri-peptide GHK and tissue remodeling. J Biomater Sci Polym Ed 2008
8. Pickart L et al. GHK peptide as a natural modulator of multiple cellular pathways in skin regeneration. Biomed Res Int 2015
9. Maquart FX et al. Stimulation of collagen synthesis in fibroblast cultures by the tripeptide-copper complex glycyl-L-histidyl-L-lysine-Cu2+. FEBS Lett 1988
10. Mulder GD et al. Enhanced healing of ulcers in patients with diabetes by topical treatment with GHK copper. Wound Repair Regen 1994
11. Miller TR et al. Effects of topical copper tripeptide complex on CO2 laser-resurfaced skin. Arch Facial Plast Surg 2006