What it is
AHK-Cu is a tripeptide — alanine, histidine, lysine, written AHK — with a copper ion held between them. PubChem files the salt form as CID 168431292: C15H24ClCuN6O4, about 451 g/mol.
The interesting thing about it is how little separates it from a better-known molecule. GHK-Cu is glycine–histidine–lysine with copper. Swap the glycine for alanine and you have AHK-Cu. The histidine and lysine, which do the work of gripping the copper, are the same in both.
Where the hair claim comes from
Nearly every page selling AHK-Cu repeats one idea: it supports hair growth. Trace it back and it arrives at one paper.
In 2007 a dermatology group at Seoul National University (Pyo and colleagues, Archives of Pharmacal Research, PMID 17703734) took human scalp hair follicles, kept them alive in culture, and added AHK-Cu at extremely low concentrations — 10⁻¹² to 10⁻⁹ molar. The follicles grew longer. Separately, dermal papilla cells — the cluster of specialised cells at the base of a follicle that steers its growth — multiplied faster.
The authors also looked at whether AHK-Cu kept those cells from dying. Fewer died at the highest concentration, but they state the difference was not statistically significant. Protein markers of cell death (cleaved caspase-3 and PARP) fell and the Bcl-2/Bax ratio rose, which points the same way.
That is a careful, honest laboratory study. It is also a study of tissue in a dish. A follicle in culture has no blood supply, no immune system and no hormones driving it through its cycle; a substance applied to a scalp has to get through skin first.
What has not been done
PubMed searched on 2026-10-28 for AHK-Cu and its chemical name returns 31 records, but most are about unrelated chemistry that happens to contain the letters Ala-His-Lys: copper-binding studies, a selenium peptide from soybean, a tumour imaging probe. The hair-follicle paper is the only one that tested AHK-Cu on human hair tissue.
No placebo-controlled trial of AHK-Cu on human scalp or skin was found. ClinicalTrials.gov has one record naming it — NCT07888595, an anti-ageing protocol enrolling by invitation — in which AHK-Cu is one of five small peptides in a serum (with GHK-Cu, epitalon, Pro-Gly-Pro and Cys-Leu-Val), given alongside oral supplements and measured with "ageing clocks". Whatever it finds, it cannot assign to AHK-Cu.
A plain comparison of the two copper tripeptides
| GHK-Cu | AHK-Cu | |
|---|---|---|
| Sequence | Gly-His-Lys + Cu²⁺ | Ala-His-Lys + Cu²⁺ |
| Found in the body | Yes — first isolated from human plasma | Not described as a natural molecule |
| Main claim | Skin repair and collagen | Hair growth |
| Human evidence | Some small skin studies (see its entry) | None published for the molecule alone |
This table compares two molecules, not two products. For what either ingredient is said to do in a skin or hair formula, PeptideGlowJournal's AHK-Cu ingredient page covers the cosmetic side.
Where it stands
As a medicine: not approved anywhere, for any use.
As an ingredient: sold by cosmetic-ingredient and research-chemical suppliers; it appears on ingredient lists, usually beside GHK-Cu.
Evidence in people: none published for AHK-Cu on its own. The best available evidence is one 2007 study of human follicles outside the body.
If hair loss is the reason for looking this up, the approved treatments and the causes worth ruling out are a conversation for a dermatologist; this entry describes the molecule only.
Last checked
2026-10-28.