AHK-Cu is a copper peptide made of three amino acids (alanine, histidine and lysine) bound to copper. It is sold in hair serums as a cousin of the better-known GHK-Cu. In a 2007 lab study, AHK-Cu lengthened human hair follicles kept alive in culture,[1] but no human trial of AHK-Cu has been published, and it is not an approved drug.[5]
This profile covers what AHK-Cu is, what the lab and animal research shows, how it differs from GHK-Cu, side effects and its regulatory status.
What is AHK-Cu?
AHK-Cu is short for L-alanyl-L-histidyl-L-lysine copper.[1] ProCyte Corp tested it in mice in a 1990s hair-growth patent, although the patent’s claims exclude AHK-Cu itself.[2] Today it is mainly sold online as a cosmetic ingredient for the scalp and, less often, as injectable vials.
Unlike GHK, which was first isolated from human blood,[7] we found no reports of AHK occurring naturally in the body.
What the research shows
The evidence for AHK-Cu is very limited:
- Human hair follicles in a dish (Seoul, 2007): researchers at Seoul National University exposed human scalp hair follicles and dermal papilla cells, the cells at the base of each follicle that control growth, to tiny amounts of AHK-Cu. The follicles grew longer and the cells multiplied. AHK-Cu also shifted markers of cell death in a favorable direction, though the drop in dying cells was not statistically significant.[1]
- Mice (ProCyte patent): the patent describes injecting AHK-Cu and related copper peptides into the skin of mice, producing patches of hair growth around injection sites, and applying it to the skin at 0.1% to 0.5%. The full data appear only in the patent, not in a peer-reviewed journal.[2]
- Other lab work: a Korean team linked AHK (without copper) to vitamin C and found it boosted bone-forming signals in mouse cells. This says nothing about hair.[3]
We found no published human study of AHK-Cu, for hair or anything else.
What the Seoul study actually measured
The 2007 study is worth reading closely, because it is the main source for AHK-Cu hair claims. The team kept hair follicles from human scalp alive in the lab and measured how much they grew. AHK-Cu worked at extremely low concentrations, between one trillionth and one billionth of a mole per liter.[1]
The researchers also looked at why. In dermal papilla cells, AHK-Cu raised the ratio of Bcl-2 to Bax, two proteins that help decide whether a cell survives or self-destructs, and lowered markers of active cell death (cleaved caspase-3 and PARP). The authors proposed that AHK-Cu may support follicle growth by helping these cells multiply and survive.[1]
Those are lab results only. A follicle in a dish is not a scalp: it has no blood supply, no hormones and no immune system, and the study did not test a serum, a dose for people or how much AHK-Cu gets through the skin.[1]
AHK-Cu vs GHK-Cu
| AHK-Cu | GHK-Cu | |
|---|---|---|
| Amino acids | Alanine, histidine, lysine[1] | Glycine, histidine, lysine[7] |
| Found in the body | No reports found | Yes, in human blood[7] |
| Hair evidence | Lab follicles and mice[1][2] | Small human trial: 2% serum increased eyebrow hair count[8] |
| FDA compounding review | Not nominated[5] | Under evaluation for non-injectable use[5] |
For the fuller copper peptide picture, see our GHK-Cu profile. For other repair peptides, see BPC-157.
AHK-Cu dosage
There is no studied human dose. The research used:
| Setting | Amount |
|---|---|
| Hair follicles in culture | Very dilute solutions (1 trillionth to 1 billionth of a mole per liter)[1] |
| Mouse skin (patent) | 0.1% to 0.5% applied to the skin[2] |
| Humans | Never studied |
Forum users describe mixing serums at about 2.5% to 3%, figures that have not been tested in any trial.[11][12] For converting a vial’s milligrams into syringe units, see our peptide calculator; it does not make an untested dose safe.
AHK-Cu side effects
- No human safety data: because AHK-Cu has not been tested in people, its side effects are unknown.[1]
- Forum reports: one user applying an AHK product nightly described facial puffiness, flushing he linked to alcohol in the product, and sun sensitivity.[11]
- Copper: the NIH sets the adult upper limit for copper from food and supplements at 10 mg a day, based on liver damage at higher intakes. People with Wilson’s disease are at particular risk from extra copper.[9]
- Injections: no study has tested injected AHK-Cu in humans. FDA has not evaluated it; a related peptide, injectable GHK-Cu, was previously on FDA’s list of substances that may pose significant safety risks.[6]
Approved hair-loss treatments to discuss instead
If you are losing hair, there are FDA-approved treatments, backed by clinical trial data, unlike AHK-Cu:
- Minoxidil 5% topical solution is sold without a prescription to regrow hair on the top of the scalp in men. The label says to apply 1 mL twice a day, that results may take 2 to 4 months, and that hair loss returns if you stop. It also says to stop and ask a doctor for chest pain, a racing heartbeat, dizziness or swelling.[13]
- Finasteride 1 mg is a once-daily prescription tablet for male pattern hair loss in men only. It must not be used by women who are or may become pregnant, who should also avoid handling crushed or broken tablets.[14]
Questions worth asking a doctor or dermatologist: What type of hair loss do I have, and what is causing it? Is an approved treatment right for me, and how long before I would see a change?
Is AHK-Cu legal?
- Cosmetics: AHK-Cu is sold as a cosmetic ingredient. FDA says products claiming to restore hair growth are regulated as drugs, even when sold as cosmetics.[4]
- Not an approved drug: AHK-Cu is not FDA-approved, and it does not appear on FDA’s May 2026 list of substances nominated for compounding.[5]
- Safety list: AHK-Cu is not on FDA’s list of compounding substances that may pose significant safety risks.[6]
- Sport: AHK-Cu is not named on WADA’s 2026 Prohibited List. WADA’s S0 category bans any substance not covered elsewhere that has no current approval for human therapeutic use, so athletes should check with their anti-doping organization.[10]
This is general information, not legal advice.
