AHK-Cu is a small synthetic copper peptide: the three amino acids alanine, histidine and lysine (Ala-His-Lys, or AHK) bound to a copper(II) ion. It is a close structural relative of GHK-Cu, the better-studied copper peptide that occurs naturally in the human body, and differs from it only in the first amino acid (alanine instead of glycine).
AHK-Cu is marketed mainly for hair and skin. The evidence behind those claims is very thin. The key published study is a 2007 laboratory study on isolated human hair follicles and cultured scalp cells. No controlled human trials of AHK-Cu have been published, and there are no published data on how it is absorbed or cleared in people.
This page summarizes what the laboratory studies and regulators report. It is for education only and is not medical advice.
| Property | Detail |
|---|---|
| Class | Synthetic copper-binding tripeptide complex |
| Sequence | L-alanyl-L-histidyl-L-lysine, complexed with Cu(II) |
| Peptide (AHK) | C₁₅H₂₆N₆O₄, 354.41 g/mol, CAS 126828-32-8 (PubChem) |
| Copper complex | Listed as the monohydrochloride, CAS 682809-81-0 (PubChem) |
| Closest relative | GHK-Cu (glycine in place of alanine) |
| Studied concentrations | 10⁻¹²–10⁻⁹ M in human hair follicles and cell culture |
| Human trials | None published |
| Half-life | No published pharmacokinetic data |
| Approval status | Not an approved drug; no approved product found |
| WADA status | Not named; S0 covers unapproved pharmacological substances |
What it is
AHK is a tripeptide (a chain of three amino acids). PubChem lists it as L-alanyl-L-histidyl-L-lysine, formula C₁₅H₂₆N₆O₄, molecular weight 354.41 g/mol (PubChem CID 7408502). The copper complex has a separate record, described as the copper monohydrochloride salt (PubChem CID 168431292).
Its design borrows from GHK (Gly-His-Lys), a naturally occurring human peptide that binds copper with an affinity similar to the copper-transport site on albumin (Pickart, J Biomater Sci Polym Ed 2008). AHK keeps the histidine and lysine and swaps the first residue. A 2026 review classifies AHK-Cu as a synthetic analog that shares GHK’s copper-binding motif but “rests on a thin, poorly characterized evidence base” (Mateescu et al., Pharmaceutics 2026).
| Feature | AHK-Cu | GHK-Cu |
|---|---|---|
| Sequence | Ala-His-Lys + Cu(II) | Gly-His-Lys + Cu(II) |
| Origin | Synthetic | Naturally occurring human peptide |
| Published research | One primary hair-follicle study (2007) | Decades of lab, animal and some human skin studies |
| Human trials | None | Controlled studies on aged skin and some wound-healing data |
How the copper binds
Both peptides have histidine in the second position. Chemists call this the N-terminal “Xxx-His” motif. In peptides with this motif, copper(II) is held by three nitrogen atoms from the peptide plus one outside ligand (Gonzalez et al., Inorg Chem 2017). This differs from the four-nitrogen binding of the albumin-type “Xxx-Zzz-His” motif. No study we found has measured the copper-binding strength of AHK itself.
How it works in the body
No study has measured AHK-Cu in human or animal blood, so its absorption, half-life and breakdown are unknown. Any half-life figure quoted for it online is not based on published measurements.
The proposed mechanism comes from cell culture only. The 2007 study describes the tripeptide-copper complex as stimulating dermal fibroblast growth, raising their output of vascular endothelial growth factor (VEGF, a signal for new blood vessels) and lowering secretion of transforming growth factor-beta1 (TGF-β1) (Pyo et al., Arch Pharm Res 2007). In dermal papilla cells, it shifted markers of programmed cell death (apoptosis) in a protective direction, described below.
What the research shows
Human hair follicles in the lab
The main study came from Seoul National University’s dermatology department (Pyo et al., Arch Pharm Res 2007). The researchers tested AHK-Cu on two models:
- Isolated human hair follicles kept alive in culture (ex vivo). AHK-Cu at 10⁻¹²–10⁻⁹ M stimulated hair follicle elongation.
- Cultured dermal papilla cells. These specialized fibroblasts at the base of the follicle control hair growth. AHK-Cu over the same range stimulated their proliferation.
At 10⁻⁹ M, the study reported these effects on apoptosis in dermal papilla cells:
| Measure | Effect of AHK-Cu (10⁻⁹ M) |
|---|---|
| Number of apoptotic cells (annexin V / PI staining) | Lower, but not statistically significant |
| Bcl-2/Bax ratio (higher favors cell survival) | Increased |
| Cleaved caspase-3 and cleaved PARP (markers of apoptosis) | Reduced |
The authors concluded that AHK-Cu may promote follicle growth by stimulating dermal papilla cell proliferation and limiting their apoptosis. The abstract does not report the size of the elongation effect or the number of follicles, and the full text was not accessible to us.
A 2026 review of peptides for hair loss lists AHK-Cu only under “experimental evidence” (ex vivo and in vitro). It notes that its signaling mechanism is less well characterized than that of GHK-Cu (Fan et al., Biomedicines 2026). The same review lists no animal or human studies of AHK-Cu.
Related AHK research without copper
A different molecule, AHK linked to vitamin C (Vit C-AHK), has been studied in mouse muscle-precursor cells in culture. It enhanced BMP-2-driven bone-cell differentiation through Smad1/5/8 and MAPK signaling (Jung et al., Differentiation 2018). This compound contains no copper and the work is cell culture only, so it says nothing direct about AHK-Cu in people.
What has not been studied
As of this writing, we found no published studies of AHK-Cu that report:
- hair counts, hair density or hair loss outcomes in people;
- skin aging, wound healing or collagen outcomes in people;
- any effect on muscle, tendon, joint or injury recovery in animals or humans;
- pharmacokinetics, dose-ranging or toxicology.
Claims about these uses rely on extrapolation from GHK-Cu or from the single cell-culture study above.
Side effects and risks
No human safety data
Because no clinical studies exist, there are no measured rates of side effects for AHK-Cu by any route. Its safety in pregnancy, in children and alongside other drugs is unknown.
Injected peptide products
AHK-Cu does not appear on FDA’s page of bulk substances flagged as potential compounding safety risks. FDA did place injectable GHK-Cu, its closest relative, on that list. FDA noted a possible risk of immune reactions (immunogenicity) from aggregation and peptide-related impurities, and limited human safety data; that nomination was later withdrawn by the nominator (FDA). The same quality concerns about purity, identity and sterility apply to any unregulated injectable peptide, but FDA has not assessed AHK-Cu specifically.
Copper
Copper is a redox-active metal. The 2026 Pharmaceutics review names control of loosely bound copper as the main safety and formulation issue for copper peptides as a class (Mateescu et al., Pharmaceutics 2026). How much copper AHK-Cu products release, and what that means in the body, has not been studied.
Legal status and use outside medicine
- Drug approval. We found no approved drug product containing AHK-Cu in the US, EU or elsewhere. It appears in cosmetic products marketed with hair and skin claims (Mateescu et al., Pharmaceutics 2026).
- US controlled substances. AHK-Cu is not an anabolic steroid and is not named in Schedule III (21 CFR 1308.13).
- Sport. AHK-Cu is not named on the WADA list. Class S0 prohibits at all times any pharmacological substance not covered elsewhere on the list “with no current approval by any governmental regulatory health authority for human therapeutic use” (WADA 2026 Prohibited List). An unapproved peptide used for its biological effects could fall under this catch-all class. We found no specific WADA ruling on AHK-Cu.
Key takeaways
- A synthetic cousin of GHK-Cu. AHK-Cu is Ala-His-Lys bound to copper, differing from GHK-Cu only in its first amino acid. See the GHK-Cu page for the larger body of research on that peptide.
- Evidence is laboratory-only. The key primary study (2007) showed hair follicle elongation and dermal papilla cell growth in isolated human tissue and cell culture.
- No human trials. There are no published clinical studies on hair, skin, healing or recovery outcomes.
- No pharmacokinetic data. Half-life, absorption and effective doses in people are unknown; quoted half-lives are not based on published measurements.
- Unregulated products. It is not an approved drug, FDA has not reviewed its safety, and WADA’s S0 catch-all class covers unapproved substances.
Sources
- Pyo HK, Yoo HG, Won CH, et al. The effect of tripeptide-copper complex on human hair growth in vitro. Arch Pharm Res. 2007;30(7):834–839. PubMed.
- National Center for Biotechnology Information. Ala-His-Lys, PubChem CID 7408502. PubChem.
- National Center for Biotechnology Information. AHK-Cu, PubChem CID 168431292. PubChem.
- Pickart L. The human tri-peptide GHK and tissue remodeling. J Biomater Sci Polym Ed. 2008;19(8):969–988. PubMed.
- Gonzalez P, Vileno B, Bossak K, et al. Cu(II) binding to the peptide Ala-His-His, a chimera of the canonical Cu(II)-binding motifs Xxx-His and Xxx-Zzz-His. Inorg Chem. 2017;56(24):14870–14879. PubMed.
- Mateescu DM, Gavrilescu DM, Mincioaga RI, et al. GHK-Cu as a bioactive metallopeptide and drug-delivery cargo: coordination chemistry, formulation science, therapeutic evidence, and a translational roadmap. Pharmaceutics. 2026;18(9):1077. PubMed.
- Fan C, Chen Y, Huang Q, et al. Overview of short peptides for hair loss. Biomedicines. 2026;14(4):864. PubMed.
- Jung JI, Park KY, Lee Y, et al. Vitamin C-linker-conjugated tripeptide AHK stimulates BMP-2-induced osteogenic differentiation of mouse myoblast C2C12 cells. Differentiation. 2018;101:1–7. PubMed.
- US Food and Drug Administration. Certain bulk drug substances for use in compounding that may present significant safety risks (content current as of April 22, 2026). FDA.
- US Drug Enforcement Administration. Schedule III, 21 CFR 1308.13. eCFR.
- World Anti-Doping Agency. World Anti-Doping Code International Standard: Prohibited List 2026 (in effect from January 1, 2026). WADA 2026 Prohibited List.