AHK

Also known as: Alanine-Histidine-Lysine, AHK tripeptide, Ala-His-Lys

Evidence: Anecdotal

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Overview

Tripeptide Ala-His-Lys; no published study tests the free peptide. Its copper complex AHK-Cu has ex vivo human hair follicle data and its own catalog entry.

AHK (Ala-His-Lys) is a tripeptide sold for hair and skin products. Every hair study found used its copper complex, AHK-Cu, tested on human hair follicles ex vivo (Pyo 2007); a 2026 review lists only ex vivo data (Fan 2026). Those results belong to the AHK-Cu entry and do not transfer to the free peptide. The only other paper used a vitamin C-linker conjugate of AHK in mouse myoblast cells (Jung 2018). No human trial exists for AHK in any form.

Benefits

None published for free AHK. The copper complex AHK-Cu has ex vivo human hair follicle data (see AHK-Cu entry)

Dosing reference

Research dose: Topical application

Topical. No published concentration or dose for the free tripeptide.

Mechanism

Unknown for the free peptide. The old text's VEGF, Wnt and anagen claims came from GHK-Cu and AHK-Cu without a source. AHK binds copper to form AHK-Cu, which was tested on human hair follicles ex vivo (Pyo 2007); see that entry. A vitamin C-linker conjugate of AHK stimulated BMP-2-induced osteogenic differentiation in mouse C2C12 cells (Jung 2018).

Evidence

Anecdotal: no peer-reviewed data

No published study of free AHK in any model
A vitamin C-linker conjugate of AHK stimulated BMP-2-induced osteogenic differentiation of mouse C2C12 myoblasts (Jung et al., 2018)
Human-trial status: none. Only the copper complex AHK-Cu has hair data, on human follicles ex vivo, with a non-significant change in apoptosis (Pyo et al., 2007; Fan et al., 2026); see the AHK-Cu entry

References

Side effects

No published safety data for the free tripeptide in any species. Commonly reported (anecdotal): irritation, redness or stinging with topical peptide products.

Storage

Storage: Room temperature, away from light
Lyophilized: 2 years at room temp
Reconstituted: N/A (ready to use)

Pharmacology

Half-life: No published pharmacokinetic data in any species
Bioavailability: Not measured; no skin penetration study of the free tripeptide has been published
Molecular weight: 354.41 Da
Sequence: Ala-His-Lys

AHK