GHK-Cu
Skin Health, Anti-Aging
In short
- A naturally occurring copper-binding tripeptide (glycyl-L-histidyl-L-lysine) found in human plasma, with levels declining substantially with age.
- The best-evidenced use is topical, in cosmetic dermatology, where controlled studies exist.
- Injected use has essentially no human evidence and introduces a genuine consideration: it is a copper complex, and copper has a narrow safe range.
- Widely used in commercial skincare, so the topical safety record is broad in practice.
- Not approved as a drug for any indication.
Structure
How it works
GHK is a tripeptide that binds copper(II) with high affinity. The complex is reported to stimulate collagen and glycosaminoglycan synthesis in fibroblasts, promote angiogenesis, and modulate expression of a large number of genes involved in tissue remodelling and antioxidant defence.
Copper itself is a required cofactor for lysyl oxidase, the enzyme that cross-links collagen and elastin, which gives a plausible mechanism for the skin effects.
Plasma GHK falls from roughly 200 ng/mL in young adults to about 80 ng/mL by age 60, which is the basis for framing it as an age-related decline.
What the research shows
Topical: several controlled cosmetic studies report improvements in skin density, wrinkle depth, and elasticity, generally over 12 weeks. The effect sizes are cosmetic in scale, and this is the strongest part of the evidence base.
Wound healing: animal studies report accelerated closure and improved tissue quality.
Hair: some studies report effects on follicles, and GHK derivatives appear in commercial hair products.
Injected use for systemic repair has no controlled human trials.
Dosing in the literature
Figures below are quoted from published studies, with the species or population they were measured in. They are records of what was studied, not recommendations.
| Studied in | Amount | Route | Source |
|---|---|---|---|
| Human — topical cosmetic studies | Typically 1–3 mg/mL in a cream or serum, applied twice daily for 12 weeks | topical | PubMed |
| Animal — wound healing models | Varies widely by model; see source | topical or injected | PubMed |
Commonly reported ranges
These are amounts people report using. They are not from any study, have not been evaluated for safety, and are reproduced here only because they circulate widely and are better seen alongside the evidence than instead of it.
| Reported by | Amount | Route |
|---|---|---|
| Commonly reported for injected use | 1–2 mg daily | subcutaneous |
No published human pharmacokinetic study establishes a dose, interval, or duration for this compound. Community figures below have no trial behind them and are reports of practice, not evidence. The specific consideration for injected use is copper load. Copper is essential but has a narrow therapeutic window, and chronic excess causes hepatic and neurological toxicity. Topical application does not raise systemic copper meaningfully; repeated injection is a different exposure, and no study has characterised it.
Handling and storage
Topical formulations are the well-studied route and are available commercially without reconstitution.
For the injectable research-market form, standard lyophilised handling applies. The solution is a distinctive blue from the copper complex; that colour is expected rather than a sign of contamination.
Some users report subcutaneous injection causes more local irritation than other peptides, consistent with the copper content.
Side effects
Topical: generally well tolerated. Irritation, redness, and contact sensitivity occur in some people, and higher concentrations are more likely to irritate.
Injected: local irritation and stinging are commonly reported.
The systemic concern is copper accumulation. Wilson disease or any condition affecting copper handling is a clear reason to avoid systemic use. Chronic copper excess is a real toxicity with hepatic and neurological consequences, and there is no study establishing what repeated injection of a copper peptide does to copper status.
Combinations
In skincare it is commonly noted that GHK-Cu and direct vitamin C (ascorbic acid) are usually applied at separate times, since the copper complex and a strong reducing agent can interact. The same caution is applied to strong acids and retinoids in the same application, mostly to limit irritation.
No systemic interaction data exists for the injected form.
Research status
A substantial literature exists, much of it from Loren Pickart, who first identified the peptide. Independent replication is present in the cosmetic dermatology literature.
The gene-expression work reporting effects on over a thousand genes is frequently cited in marketing; it describes in vitro transcriptional changes rather than clinical outcomes.
Legal status
Permitted and widely used as a cosmetic ingredient in the US, EU, and elsewhere. Not approved as a drug for any indication. The injectable research-market form is unapproved.
WADA status
Not specifically named on the Prohibited List. Falls under WADA class S0, which prohibits any pharmacological substance not currently approved by any governmental regulatory health authority for human therapeutic use. Treat it as prohibited in sport.
Conclusion
GHK-Cu is one of the few compounds here with genuine controlled human evidence — for topical cosmetic use, where it is a reasonable and well-established ingredient.
The injected use is a different proposition with no supporting evidence and a specific copper consideration that does not apply to the cream. Those two things get conflated constantly, and they should not be.
Sources
Track your own GHK-Cu protocol
Peppers logs your doses, models your levels from this half-life, tracks your vials and tells you when you will run out. Free on iPhone.
Reference and educational information only. Not medical advice. Nothing here diagnoses, treats, or prescribes, and nothing here is a recommendation to use any compound. The compounds described are research chemicals and are not approved for human consumption. Legal and anti-doping status change — the review date above is when these claims were last checked. Talk to a qualified clinician about anything you intend to take.