AHK (Tripeptide-3)

Key points

• AHK (Tripeptide-3) is a three amino acid peptide added to skincare and scalp products.
• It is marketed to support hair growth and the condition of the skin.
• On the skin, with no medicinal claims, it is regulated as a cosmetic ingredient in the UK.
• The evidence is modest, and cosmetic claims are best kept in proportion.

Quick facts

What it is

Cosmetic skincare peptide (Tripeptide-3)

Marketed for

Hair and skin condition

UK status

Legal as a cosmetic ingredient (no medicinal claims)

Evidence

Modest

How it works

Small peptides like this are used in cosmetics to signal to skin and hair follicle cells, with the aim of supporting their natural processes. Most of the supporting evidence is from laboratory and manufacturer studies.

What the evidence shows

There are studies, often from manufacturers, suggesting modest cosmetic effects. Independent, high quality trials are limited, so claims should be kept modest.

What it does not settle

• Independent high quality evidence is limited.
• Effects are usually modest and build slowly.
• Results depend on the product and how it is used.

Side effects

Common

• Usually well tolerated, though some people get mild irritation or redness. A patch test is sensible.

Report any suspected side effect through the MHRA Yellow Card scheme.

UK legal status and access

As a topical cosmetic ingredient with no medicinal claims, AHK (Tripeptide-3) is legal and widely sold in skincare and hair products. Any version sold with medicinal claims, or for injection, would fall under medicines rules.

Common questions