AHK-Cu appears on hair-serum labels and research-peptide price lists as the copper peptide "for hair", usually beside its better-known relative GHK-Cu. Both are small copper-binding peptides, and they are often treated as interchangeable. They are not the same molecule, and their research records are not remotely the same size. This entry sets out what AHK-Cu is, counts what has been published about it, and states plainly what has not been tested. It is an evidence summary, not a recommendation to use any product.
The molecule
AHK is a tripeptide: alanine – histidine – lysine. AHK-Cu is that peptide bound to a copper(II) ion. PubChem lists the peptide as CID 7408502 (molecular weight 354.41 Da) and a copper complex as CID 168431292.
GHK, the peptide in copper tripeptide-1, is glycine – histidine – lysine (CID 73587, 340.38 Da). The two differ by one amino acid in the first position, which amounts to a single extra methyl group — 14 daltons. Both place histidine second, which is the position that lets a short peptide hold a copper ion, so it is unsurprising that both bind copper. Whether they behave the same way in skin or in a hair follicle is a separate question that no study has asked.
A search trap worth knowing: the sequence Ala-His-Lys is the last three amino acids of DAHK (Asp-Ala-His-Lys), the copper-binding tip of human serum albumin. Broad PubMed searches for "alanyl-histidyl-lysine" or "Ala-His-Lys" therefore return dozens of albumin and DAHK papers — on stroke, heart attack and copper chemistry — that have nothing to do with the cosmetic ingredient. Our census below excludes them by reading each record.
The record, counted
On 30 September 2026:
| Search | Result |
|---|---|
| PubMed, exact term "AHK-Cu" | 1 record |
| PubMed, exact term "GHK-Cu" (control) | 82 records |
| PubMed, all names (AHK-Cu, AHK Cu, alanyl-histidyl-lysine, Ala-His-Lys, L-alanyl-L-histidyl-L-lysine), read one by one | 38 records; 2 about the AHK peptide itself, the rest DAHK/albumin, copper chemistry or unrelated |
| ClinicalTrials.gov, "AHK-Cu" | 0 registered studies |
PubMed reported that it could not match "copper tripeptide-3", so that name contributed nothing; no ingredient-list (INCI) name for AHK-Cu was found in this search.
The two records about the peptide itself:
- The hair-follicle study. Pyo and colleagues (2007), Department of Dermatology, Seoul National University, Archives of Pharmacal Research. Details below.
- A bone-cell study of a modified version. Jung and colleagues (2018) tested a vitamin C–linked AHK (not the copper complex) on mouse muscle-precursor cells and found it enhanced a bone-forming response. The abstract notes the vitamin C–conjugated tripeptides were originally developed for collagen synthesis or skin-cell growth, and one author lists a Korean medical-materials company. It is not a skin or hair study, and the molecule is not AHK-Cu.
What the 2007 hair-follicle study found
Pyo's group used human scalp hair follicles kept alive outside the body and cultured dermal papilla cells, the specialised cells at the base of the follicle that regulate hair growth. They applied AHK-Cu at 10⁻¹² to 10⁻⁹ M — picomolar to nanomolar concentrations.
- AHK-Cu lengthened the follicles in the dish and increased dermal papilla cell growth.
- At 10⁻⁹ M it reduced the number of dying (apoptotic) papilla cells, but the reduction was not statistically significant.
- It shifted markers linked to cell survival (a higher Bcl-2/Bax ratio; less cleaved caspase-3 and PARP), which the authors propose as the mechanism.
This is a well-designed laboratory study, and it is the main reason AHK-Cu is sold for hair. It is also the whole of the hair evidence. A follicle in a culture dish has no skin barrier to cross, no blood supply, no hormones and no immune system, and the concentrations that worked in the dish say nothing about how much of an applied serum would reach a follicle through the scalp.
How AHK-Cu gets confused with GHK-Cu
Most copper-peptide hair marketing says "GHK-Cu" and cites the 2007 study. The study used AHK-Cu. Our copper peptides for hair census found that of 18 PubMed records on copper peptides and hair, none is a randomized trial of either peptide alone, and every human study gave the copper peptide inside a mixture with other actives. The confusion runs both ways: AHK-Cu products sometimes borrow GHK-Cu's larger skin literature (summarised on our copper peptides page), and GHK-Cu products borrow AHK-Cu's follicle result. Neither transfer is supported, because no study has compared the two molecules on skin or hair.
Where AHK-Cu appears
AHK-Cu is sold in two very different forms: as a named active in topical hair serums, and as a powder on research-peptide sites. The injectable research form is outside the approval systems that govern medicines and has no published human data by any route; Medibact Guides publishes an AHK-Cu stacking page for that form; this entry does not reproduce it, and nothing on this page describes a dose or a route for a reader to use. For topical products, the question of how much of a copper peptide crosses intact scalp skin has not been measured for AHK-Cu.
What has not been studied
- Any human use of AHK-Cu, topical or injected, for hair or skin.
- A head-to-head comparison with GHK-Cu, in a dish or in people.
- Penetration through intact human scalp or facial skin.
- Safety in people: no published safety study and no registered trial.
- Combination with minoxidil or finasteride, the approved hair-loss drugs against which every hair ingredient is eventually judged (see the benchmarks on our peptides for hair growth hub).
For comparison, two hair peptides with small human trials of their own are covered in our entries on biotinoyl tripeptide-1 and acetyl tetrapeptide-3.
Sources
- PubChem compound records CID 7408502 (Ala-His-Lys), CID 168431292 (AHK-Cu), CID 73587 (GHK): synonyms, molecular formula and weight via PUG REST, read 2026-09-30.
- PubMed via NCBI E-utilities, searches run 2026-09-30 and checked for unmatched phrases: "AHK-Cu" (1), "GHK-Cu" (82), all AHK names (38, read individually).
- ClinicalTrials.gov API v2, query "AHK-Cu" (0), run 2026-09-30.
- 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):834-9 — PMID 17703734.
- Jung JI, Park KY, Lee Y, Park M, Kim J. Vitamin C-linker-conjugated tripeptide AHK stimulates BMP-2-induced osteogenic differentiation of mouse myoblast C2C12 cells. Differentiation 2018;101:1-7 — PMID 29567599.
- Gonzalez P, 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 — PMID 29190078.
- Bar-Or D, et al. An analog of the human albumin N-terminus (Asp-Ala-His-Lys) prevents formation of copper-induced reactive oxygen species. Biochem Biophys Res Commun 2001 — PMID 11396981.