01 What is GHK-Cu?
In plain English.
GHK-Cu is a small protein fragment, just three [amino acids](/glossary "Amino acid: The building blocks of proteins. A peptide is a short chain of them linked together.") (glycine, histidine, lysine), that latches onto a copper ion. The peptide is naturally present in human plasma, saliva and urine, where levels drop as we age. It's sold widely as a cosmetic ingredient in serums and creams, and as an unregulated injectable vial on research-peptide sites.
Important split: most of the real human evidence is for topical use as a skincare ingredient, small trials, often industry-adjacent, showing modest improvements in skin appearance. The injectable form popular on peptide forums has essentially no human trial data. The two routes get conflated online; we keep them separate.
02 How it works
The simple version, then the science.
GHK binds copper, and the complex appears to nudge skin cells toward a more youthful pattern of behaviour: producing more collagen and elastin, supporting wound repair, and tamping down inflammation. In lab studies it changes the expression of a large number of genes involved in tissue remodelling.
Go deeper · the proposed mechanism
In cell and animal work, GHK-Cu has been reported to stimulate fibroblast proliferation, increase collagen, elastin, glycosaminoglycan and decorin synthesis, and modulate matrix metalloproteinases. A 2010 gene-expression analysis by Pickart's group reported that GHK can reset the expression of thousands of genes in human cells toward a younger profile, a striking finding, but one that needs replication outside the originator's lab and direct linking to clinical outcomes in humans. The systemic pharmacokinetics of injected GHK-Cu in humans are not characterised in any peer-reviewed trial we can find.
03 What it's used for
Each use graded by how strong the evidence actually is.
- LimitedTopical anti-ageing (firmness, wrinkles, hydration)Several small, often industry-funded RCTs of topical GHK-Cu creams report modest improvements in firmness, fine lines and hydration. Real effect, but small samples and conflicts of interest mean the size of the benefit is uncertain.
- PreclinicalWound healingMechanistic and animal evidence is consistent, accelerated repair, better-organised collagen. The prescription form (prezatide copper acetate / Iamin) was once developed for chronic wounds, but is not in current clinical use.
- AnecdotalHair growth (topical)Marketed as a hair-loss ingredient. Strong cell-level rationale but very limited controlled human evidence specifically for GHK-Cu monotherapy.
- AnecdotalInjectable use for systemic anti-ageing / recoveryPopular on peptide forums; no published human trials of injected GHK-Cu for these purposes. Treat all claims with caution.
04 What the evidence says
For topical cosmetic use, there is a thin but genuine layer of human evidence, small randomised trials over 12 weeks reporting improvements in fine lines, firmness and hydration versus placebo or vehicle. Many of these were conducted or funded by manufacturers of GHK-Cu products, so independent replication is limited. Mechanistic work in cells and animals is much more developed, and reviews by Pickart and colleagues lay out a plausible regenerative role. Where the evidence collapses is the leap from a cosmetic ingredient applied to skin to a subcutaneous injection given for systemic effects, no controlled human trials support that use. Plasma GHK does decline with age, but it has not been shown that supplementing it via injection produces a clinical benefit in humans.
05 Dosing & administration
Reported in the literature, information not advice.
Topical cosmetic products typically contain 0.05% to 2% GHK-Cu and are applied once or twice daily; this is what the cosmetic studies tested. Reported anecdotal injection protocols vary widely and have no clinical basis. No approved human dose exists for systemic use. Anyone considering any peptide product should consult a qualified clinician, and for topical use, a dermatologist can advise on formulation and concentration.
06 Side effects & safety
Topical GHK-Cu has a long cosmetic safety history and is generally well tolerated; mild irritation or contact reactions occur occasionally. Independent reviews by cosmetic safety panels have judged it safe for use in cosmetics at the concentrations used. The safety picture for injection is entirely different: there are no controlled human safety trials, products sold online are unregulated, and copper-containing solutions raise questions about long-term local and systemic accumulation that have not been formally answered. Caution is particularly warranted in pregnancy, breastfeeding, in people with Wilson's disease or other copper-handling disorders, and in anyone with active malignancy (some lab work suggests GHK alters cancer-relevant gene expression in directions that have not been clinically validated).
07 Where to buy
Sold "research use only", so verification matters more than price.
08 Legal & regulatory status
- UKLegal as a cosmetic ingredient in skincare products. Injectable "research peptide" vials are unlicensed medicines, sold legally only as research chemicals, not for human use.
- USPermitted as a cosmetic ingredient. Not an FDA-approved drug for any indication (the historic prescription form, prezatide copper acetate / Iamin, is no longer marketed).
- EUPermitted in cosmetic products under EU/UK cosmetics regulation. Not authorised as a medicine.
- SportNot specifically named on the current WADA Prohibited List. Athletes should still verify with their anti-doping authority before use.
09 Clinical studies & research
Primary sources. Read the science yourself.