Copper signaling for follicle renewal
Topical, Injection · 503A Compounding
Educational content. This page describes AHK-Cu for informational purposes only and is not medical advice, diagnosis, or treatment. Consult a licensed provider before starting, stopping, or modifying any therapy.
Researched and maintained by the PepHookup team. Regulatory status last verified April 12, 2026.
In the one published study on this peptide, AHK-Cu increased the elongation of cultured human hair follicles and promoted proliferation of dermal papilla cells at very low concentrations (10^-12 to 10^-9 M). This remains ex vivo and in vitro evidence, not a human trial result.[1]
AHK-Cu acts on dermal papilla cells, the signaling fibroblasts that direct hair follicle cycling. At 10^-9 M it shifted these cells toward survival by raising the Bcl-2/Bax ratio and lowering cleaved caspase-3 and PARP, the markers of programmed cell death.[1]
In dermal cells, AHK-Cu raised vascular endothelial growth factor (VEGF), which supports blood supply to follicles, while lowering transforming growth factor beta-1 (TGF-beta1), a signal that drives follicles into the resting phase. A related copper tripeptide raised VEGF and bFGF in fibroblasts as well.[1][4]
The peptide delivers copper, an obligatory cofactor for lysyl oxidase, the enzyme that cross-links collagen and elastin, and for copper/zinc superoxide dismutase, a primary antioxidant defense in skin. This is the rationale for its use in regenerative formulations.[5][6]
AHK-Cu (L-alanyl-L-histidyl-L-lysine copper complex), also marketed as Copper Tripeptide-3, is a synthetic tripeptide chelated to a divalent copper ion (Cu2+). It pairs alanine, histidine, and lysine with copper, and the imidazole side chain of histidine does most of the work of holding the copper in place while the lysine amino group adds binding stability.
AHK-Cu is a close structural analog of GHK-Cu (Copper Tripeptide-1). The two differ at only the first position, where AHK-Cu carries alanine in place of glycine. That single extra methyl group is thought to make the copper-binding pocket slightly more rigid. Unlike GHK, which occurs naturally in human plasma, AHK has no documented endogenous source and is entirely synthetic. Its published research is narrow and centers on hair follicle biology, with the broader copper peptide literature, especially the much larger GHK-Cu body of work, used to fill in context.
Practically, AHK-Cu reaches consumers as an ingredient in topical cosmetic serums and hair products rather than as an approved drug. The evidence base specific to AHK-Cu is a single laboratory study, so confident claims about what it does in people are not yet supported.
The best characterized action of AHK-Cu is on dermal papilla cells, the specialized fibroblasts at the base of the follicle that coordinate hair growth and cycling. In culture, low concentrations of the peptide promoted dermal papilla cell proliferation and pushed the cells toward survival, raising the anti-apoptotic Bcl-2/Bax ratio and reducing the cleaved forms of caspase-3 and PARP that mark cells committed to death.
AHK-Cu also shifted the growth factor balance in dermal cells. It increased vascular endothelial growth factor (VEGF), which favors the new blood vessels that feed an active follicle, while decreasing transforming growth factor beta-1 (TGF-beta1), a signal that normally moves a follicle out of its growth phase and into rest.
A second layer of the mechanism is simply copper delivery. Copper is a required cofactor for lysyl oxidase, which cross-links collagen and elastin into durable connective tissue, and for copper/zinc superoxide dismutase, an antioxidant enzyme. Supplying copper in a cell-compatible peptide form is the basis for using copper tripeptides in skin and follicle formulations.
One detail matters for formulation. AHK-Cu showed a biphasic dose response in the laboratory. It was active in the picomolar to nanomolar range (10^-12 to 10^-9 M) but lost its benefit at higher concentrations. More is not better, which means the amount that actually reaches tissue, not just the amount in the bottle, is what counts.
Copper signaling for follicle renewal
AHK-Cu delivers bioavailable copper to dermal papilla cells while shifting them toward survival (higher Bcl-2/Bax ratio, lower cleaved caspase-3 and PARP). In dermal cells it raises VEGF to support follicle blood supply and lowers TGF-beta1 to favor the growth phase, and the copper it carries serves as a cofactor for lysyl oxidase and superoxide dismutase. The effect is biphasic, active at picomolar to nanomolar levels and lost at higher concentrations.
AHK-Cu at 10^-12 to 10^-9 M stimulated elongation of human hair follicles ex vivo and proliferation of dermal papilla cells. At 10^-9 M it raised the Bcl-2/Bax ratio and reduced cleaved caspase-3 and PARP, while increasing VEGF and decreasing TGF-beta1 in dermal cells. The reduction in apoptotic dermal papilla cells at 10^-9 M did not reach statistical significance, and the effect was lost at higher concentrations. This is the only study performed directly on AHK-Cu.
Pyo HK, Yoo HG, Won CH, Lee SH, Kang YJ, Eun HC, Cho KH, Kim KH · Arch Pharm Res, 30(7):834-839 (2007) · PubMed
Copper tripeptide complexes from the same family as AHK-Cu stimulated hair follicle activity in the mouse model, providing animal support for a class-wide follicle effect. This work used the broader copper peptide class rather than AHK-Cu specifically.
Trachy RE, Fors TD, Pickart L, Uno H · Ann N Y Acad Sci, 642:468-469 (1991) · PubMed
The structurally related GHK-Cu produced concentration-dependent increases in collagen, DNA, total protein, and glycosaminoglycans, with collagen synthesis stimulated about twice as much as non-collagen protein. A peptide control without copper had no effect, confirming the copper-peptide complex was responsible.
Maquart FX, Bellon G, Chaqour B, Wegrowski J, Patt LM, Trachy RE, et al. · J Clin Invest, 92(5):2368-2376 (1993) · PubMed
GHK-Cu accelerated growth of both normal and irradiated fibroblasts and increased their production of basic fibroblast growth factor and VEGF early after exposure. This supports the growth factor effects seen with AHK-Cu, though it tested the GHK form rather than AHK.
Pollard JD, Quan S, Kang T, Koch RJ · Arch Facial Plast Surg, 7(1):27-31 (2005) · PubMed
start low, go slow
Topical (serum or solution)
Topical (serum or solution): AHK-Cu is used as a cosmetic ingredient, not a prescribed drug, so there is no clinically validated dose. Because the laboratory effect was biphasic, higher is not better. A licensed provider should guide any therapeutic use.
There is no human clinical trial establishing a dose for AHK-Cu. All concentration guidance traces back to one ex vivo and in vitro study plus general copper peptide practice, and any therapeutic protocol should be set by a licensed provider.
AHK-Cu showed a biphasic dose response in the laboratory, active in the picomolar to nanomolar range and ineffective above it. The challenge with topical use is keeping the concentration that reaches tissue inside that effective window.
Copper-peptide bonds are sensitive to formulation chemistry. Avoid layering AHK-Cu with strong exfoliating acids (AHAs, BHAs) or low-pH vitamin C at the same time, since an acidic environment can destabilize the copper-peptide complex. If using several actives, separate them across the day.
No formal toxicology study has been published on AHK-Cu itself. Its safety profile is inferred from a single laboratory study and from the broader, much longer track record of copper tripeptides such as GHK-Cu used topically in cosmetics.
The related peptide GHK-Cu has been used in topical anti-aging and cosmetic products for decades without reports of significant adverse effects, but that history belongs to GHK-Cu and cannot be assumed to transfer wholesale to AHK-Cu.
No long-term human safety data exist for AHK-Cu. The single published study (Pyo et al., 2007) has not been replicated, extended to living animals, or tested in a human trial in the years since.
This information is educational and not medical advice. Anyone considering AHK-Cu beyond a cosmetic context should consult a licensed provider.
| Peptide | Primary Use | Administration | Cycle Length | Key Differentiator |
|---|---|---|---|---|
| AHK-Cu | Hair & Skin Regeneration | Topical | 8 to 12 weeks | A hair follicle-focused copper tripeptide with a single supporting laboratory study and a biphasic dose response that makes formulation precision matter |
| SS-31 (Elamipretide) | Mitochondrial restoration and rare mitochondrial disease | Subcutaneous injection (daily); IV in trials | Ongoing daily dosing | The first FDA-approved mitochondria-targeted therapeutic; binds cardiolipin on the inner mitochondrial membrane to support electron transport efficiency |
| Melanotan 1 (Afamelanotide) | Photoprotection in EPP | Subcutaneous implant | Every 2 months (ongoing) | The only FDA-approved melanocortin agonist, pairing eumelanin induction with UV-independent DNA repair through a selective MC1R mechanism |
| GHK-Cu | Anti-Aging & Skin Regeneration | Topical, Injection | 8-12 weeks | A naturally occurring copper-carrier peptide that rebuilds the skin matrix and, per gene-expression analysis, shifts expression of about a third of human genes toward repair |
| Sermorelin | GH restoration and healthy aging | Subcutaneous injection, daily at bedtime | 3-6 months | The GHRH analog with prior FDA approval and a multi-decade clinical record, preserving natural feedback rather than replacing growth hormone |
This substance does not appear on any FDA bulk drug substances list. It is classified as research-use only and cannot be legally compounded for human use.
AHK-Cu does not appear on any FDA 503A or 503B bulk drug substances list. It has no NDA, BLA, or IND. It has never been nominated for FDA evaluation. Because it is not on any bulk list, it falls outside the pathways for compounded human use, and pharmacies that prepare it for patients face FDA enforcement risk. Available only as a research-use or cosmetic ingredient.
Last verified April 12, 2026. PepHookup tracks public FDA actions. This is not legal or medical advice.
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