What the Copper Peptide GHK-Cu Does for Skin Repair, and Where the Human Evidence Stops

Patients ask me about GHK-Cu more often every month, usually after they've seen it in a blue face serum and then learned that it comes as an injection too. They want to know whether it rebuilds collagen, and whether a shot under the skin does more than a cream on top of it. The laboratory work behind this molecule is better than I expected, and the human research stops where the injection begins.

A three-amino-acid peptide from human plasma

GHK is a tripeptide, a chain of three amino acids (glycine, histidine, and lysine), that occurs naturally in human blood. Loren Pickart isolated it from human serum in 1973 as a factor that prolonged the survival of normal liver cells [1]. The peptide binds copper tightly, and the complex it forms, written GHK-Cu, is what fills the serums and the vials. Maquart and colleagues pointed out in 1988 that the same three-amino-acid sequence sits inside one of the chains of type I collagen, the main structural protein of skin, which suggests that the enzymes clearing damaged collagen from a wound release GHK, and that the fragment then tells nearby cells to rebuild [2].

Pickart's reviews report that plasma GHK runs about 200 ng/mL at age 20 and falls to about 80 ng/mL by age 60 [3]. Those figures come from Pickart's own reports, I can't find an independent replication, and the reviews list a company called Skin Biology as the authors' affiliation, so I treat the decline as plausible and unconfirmed.

What GHK-Cu does in cells

GHK-Cu pushes fibroblasts, the cells that build the skin's scaffolding, to make more collagen. In that 1988 study, cultured fibroblasts began increasing their collagen synthesis at picomolar concentrations of GHK-Cu, with the peak at one nanomolar (a billionth of a mole per liter), independent of any change in cell number [2]. The same French group later found that GHK-Cu raised the fibroblasts' output of matrix metalloproteinase-2, an enzyme that cuts old collagen, along with the two inhibitors that restrain it [4]. This means the peptide drives remodeling, the clearing of damaged matrix along with the laying down of new. In that experiment copper ions reproduced the enzyme effect while the bare peptide didn't, a hint that part of GHK's job is delivering copper.

GHK also changes which genes a cell switches on. In 2012 Campbell and colleagues profiled lung tissue from smokers with emphysema, identified 127 genes whose activity tracked with the severity of lung destruction, and searched the Connectivity Map, a database of how compounds shift gene expression, for anything that pushed those genes the opposite way. GHK came up, and fibroblasts from diseased lungs recovered their ability to contract and remodel collagen when the team treated them with it [5]. That's a computational match confirmed in a culture dish, and no one has tested GHK against emphysema in a patient.

Why the copper matters

Copper is the required cofactor for lysyl oxidase, the enzyme that cross-links collagen and elastin fibers into a network that can bear load. Rucker and colleagues, in a 1998 review in the American Journal of Clinical Nutrition, reported that dietary copper doesn't change how much lysyl oxidase a tissue makes, yet it directly controls how much of that enzyme works [6]. Collagen without cross-links is weak, so a molecule that stimulates collagen synthesis and also carries copper to the site makes biological sense. I think that pairing explains much of what GHK-Cu does in a wound, though that's my read, and no experiment has separated the two effects (our post on the gut, minerals, and skin covers copper's structural role).

Wounds in animals

In animals, GHK-Cu increases the amount of new tissue a wound lays down. In 1993 Maquart and colleagues implanted stainless steel mesh chambers under the skin of rats, injected GHK-Cu into the chambers, and measured what grew inside. Collagen, total protein, DNA, and glycosaminoglycans (the water-holding sugar chains that fill the space between collagen fibers) all rose with the dose, collagen synthesis rose twice as much as the synthesis of other proteins, and a control tripeptide had no significant effect [7]. Pickart's review lists similar wound results in mice, pigs, and the foot pads of dogs [3]. That experiment is the closest the literature comes to the injection patients ask me about, and it delivered the peptide straight into a rodent's wound.

The human evidence is topical and mixed

I can find three randomized human trials of GHK-Cu on PubMed, and all three applied it to the skin. Mulder and colleagues, in a 1994 multicenter, evaluator-blinded trial in diabetic foot ulcers, reported a median 98.5 percent closure of plantar ulcers with GHK-Cu gel compared with 60.8 percent with the vehicle gel, and an infection rate of 7 percent compared with 34 percent [8]. Venous leg ulcers went the other way, since in an 86-patient trial a 0.4 percent tripeptide-copper cream performed no better than placebo while silver sulfadiazine beat both [9]. The only randomized cosmetic trial enrolled 13 patients after carbon dioxide laser resurfacing around the mouth, and blinded evaluators saw no difference in redness, wrinkles, or skin quality with GHK-Cu products, although the patients using them reported more satisfaction [10]. The cosmetic studies quoted most often, 12-week trials of face and eye creams in 41 to 71 women, trace back to a 2002 dermatology meeting and a book chapter that Pickart's review summarizes, and I can't find them published as full peer-reviewed papers [3].

Why inject it at all? GHK-Cu is hydrophilic, meaning it dissolves in water and permeates the fatty outer layer of the skin poorly [11], and that's the argument for a needle. The chemistry is sound, yet I can find no randomized human trial of injected GHK-Cu for any purpose, and no published human data on the dose, the blood levels it produces, or the rate of side effects. No GHK-Cu product has FDA approval as a drug, and the compounded injection isn't FDA-approved.

Copper balance, and who shouldn't use it

Copper is a nutrient with a narrow comfortable range, and more isn't automatically better. Zinc and copper compete for absorption, so people who take high-dose zinc can run their copper low, and the remedy is food, not a peptide (see our post on zinc and copper balance). Your intestine normally decides how much copper to let in, and an injection bypasses that checkpoint, which is my reason for caution about prolonged use.

Anyone with Wilson disease, the inherited disorder in which mutations in the ATP7B copper transporter leave copper accumulating in the liver and brain, should never use GHK-Cu [12]. I'd also keep it away from anyone with active cancer. The title of Pickart's original paper tells you that the peptide stimulated growth in cancerous liver tissue as well as prolonging the survival of normal cells [1], and a molecule that speeds cell growth and draws blood vessel cells toward it [3] deserves that respect until someone proves it safe. Pregnancy and breastfeeding have no safety data. As far as I know the World Anti-Doping Agency's prohibited list doesn't name GHK-Cu, though it includes a catch-all category for unapproved substances, so a tested athlete should clear any injected peptide with their governing body first.

What to do

If your goal is better skin or faster healing, the basics come first. Eat enough protein and get your copper from food (liver, shellfish, and nuts carry the most, and our guide to minerals in animal foods has the numbers). Don't take zinc by itself for months, keep your blood sugar controlled, avoid sunburn, and don't smoke. For a chronic wound, remember that every patient in the diabetic ulcer trial also received debridement, pressure-relieving footwear, and diabetes education, so the gel added to that care and didn't replace it [8]. A topical GHK-Cu product is a reasonable, low-risk experiment for your skin, though the one randomized cosmetic trial found no objective benefit [10].

If you still want to try the injection, understand that you'd be relying on rat wound chambers and cell cultures, not on human trials. Do it under a physician who screens you for copper disorders and liver disease, keeps the course short, and tells you plainly that it's experimental, which is how we approach it. Whether injecting GHK-Cu improves human skin is a question nobody has answered yet.

Ask a provider about GHK-Cu

References

1. Pickart L, Thaler MM. Tripeptide in human serum which prolongs survival of normal liver cells and stimulates growth in neoplastic liver. Nat New Biol. 1973. PMID: 4349963
2. Maquart FX, Pickart L, Laurent M, et al. Stimulation of collagen synthesis in fibroblast cultures by the tripeptide-copper complex glycyl-L-histidyl-L-lysine-Cu2+. FEBS Lett. 1988. PMID: 3169264
3. Pickart L, Vasquez-Soltero JM, Margolina A. GHK Peptide as a Natural Modulator of Multiple Cellular Pathways in Skin Regeneration. Biomed Res Int. 2015. PMID: 26236730
4. Siméon A, Emonard H, Hornebeck W, et al. The tripeptide-copper complex glycyl-L-histidyl-L-lysine-Cu2+ stimulates matrix metalloproteinase-2 expression by fibroblast cultures. Life Sci. 2000. PMID: 11045606
5. Campbell JD, McDonough JE, Zeskind JE, et al. A gene expression signature of emphysema-related lung destruction and its reversal by the tripeptide GHK. Genome Med. 2012. PMID: 22937864
6. Rucker RB, Kosonen T, Clegg MS, et al. Copper, lysyl oxidase, and extracellular matrix protein cross-linking. Am J Clin Nutr. 1998. PMID: 9587142
7. Maquart FX, Bellon G, Chaqour B, et al. In vivo stimulation of connective tissue accumulation by the tripeptide-copper complex glycyl-L-histidyl-L-lysine-Cu2+ in rat experimental wounds. J Clin Invest. 1993. PMID: 8227353
8. Mulder GD, Patt LM, Sanders L, et al. Enhanced healing of ulcers in patients with diabetes by topical treatment with glycyl-l-histidyl-l-lysine copper. Wound Repair Regen. 1994. PMID: 17147644
9. Bishop JB, Phillips LG, Mustoe TA, et al. A prospective randomized evaluator-blinded trial of two potential wound healing agents for the treatment of venous stasis ulcers. J Vasc Surg. 1992. PMID: 1495150
10. Miller TR, Wagner JD, Baack BR, et al. Effects of topical copper tripeptide complex on CO2 laser-resurfaced skin. Arch Facial Plast Surg. 2006. PMID: 16847171
11. Ogórek K, Nowak K, Wadych E, et al. Are We Ready to Measure Skin Permeation of Modern Antiaging GHK-Cu Tripeptide Encapsulated in Liposomes? Molecules. 2025. PMID: 39795193
12. Członkowska A, Litwin T, Dusek P, et al. Wilson disease. Nat Rev Dis Primers. 2018. PMID: 30190489