GHK-Cu for skin and hair: what holds up

What GHK-Cu is

GHK-Cu is a short peptide: three amino acids (glycine, histidine, lysine) bound to a single copper ion. It occurs naturally in human blood plasma. According to Loren Pickart, who discovered GHK, plasma levels sit around 200 ng/mL at age 20 and fall to about 80 ng/mL by age 60.

In cell culture, GHK-Cu raised collagen production by fibroblasts. You will see it on serum bottles as "copper tripeptide-1" or "copper peptide." It is also sold in injectable vials, though nobody has published a study of injected GHK-Cu on its own.

Skin: what the human studies show

The 2026 systematic review by Mokhtar and colleagues searched for every published study of GHK-Cu in aesthetic medicine. Of the 20 studies it found, 18 were preclinical (cells, tissue, or animals). Just two were randomised controlled trials in people.

One of those two trials randomised patients to skin care with or without GHK-Cu for 12 weeks after CO₂ laser resurfacing; 13 completed it. Blinded raters found no difference in wrinkles, skin quality, or redness. Only the patients' own questionnaire favoured GHK-Cu (P = 0.04). The review's other trial reported less wrinkle volume and depth than controls; the abstract does not give its size.

The wound-healing trials tell a mixed story. A multicentre, randomised, evaluator-blinded, placebo-controlled trial tested GHK-Cu gel (Iamin Gel) on diabetic neuropathic ulcers. In plantar ulcers, median closure was 98.5% with GHK-Cu versus 60.8% with vehicle (p < 0.05), and infections were 7% versus 34% when the gel was started right after debridement. In 86 patients with venous stasis ulcers who completed a three-arm trial, 0.4% GHK-Cu cream performed no better than placebo.

There are also two studies led by Leyden and colleagues that were presented at the American Academy of Dermatology in 2002 but never published as full papers: a 12-week facial cream study in 71 women and a 12-week eye cream study in 41 women. They are described in a review by Pickart as showing reduced wrinkles and improved skin density. Because they remain conference abstracts, their methods and complete data have never been peer reviewed.

A separate 2025 review put it plainly: there is "a surprising absence of clinical studies" using GHK-Cu in anti-wrinkle products.

Hair: lab work and cocktails

In a lab study on human hair follicles kept alive outside the body, a related copper peptide, AHK-Cu (not GHK-Cu), lengthened the follicles. A review by Pickart, who discovered GHK, says it speeds wound healing of hair follicles, without giving the species or the human data.

The only human injection data come from a product called QR678: a cocktail of six ingredients (including copper tripeptide-1, growth factors, and thymosin beta-4) injected into the scalp. An open-label, single-arm study of 1,000 patients reported less hair fall and more hair. Because six active ingredients were in the syringe and there was no comparison group, the study says nothing about what GHK-Cu itself did.

No controlled human trial of GHK-Cu alone for hair loss was found in PubMed.

Is GHK-Cu approved?

GHK-Cu is not an approved medicine. It is sold as a cosmetic ingredient.

The company ProCyte developed GHK-Cu gel (Iamin Gel) as a wound-healing drug. The gel was not approved as a medicine. In 1996, the US FDA cleared it only as a wound dressing, which is a medical device.

For compounding pharmacies: injectable GHK-Cu was placed in the FDA's 503A Category 2 (substances that may present significant safety risks). It is now listed as "nominated but withdrawn," with the FDA citing limited human data. Non-injectable GHK-Cu (for topical compounding) was returned to Category 1 in May 2026, and the FDA says it plans to consult its advisory committee before the end of February 2027.

Doses used in studies

Every published human trial of GHK-Cu used topical application:

• 0.4% tripeptide copper cream on venous ulcers
• A metered daily dose of GHK-Cu gel on diabetic neuropathic ulcers
• GHK-Cu skin care products for 12 weeks after laser resurfacing

No study has tested injected GHK-Cu on its own at any dose in people. The injectable route has no published dosing data behind it.

Safety

The trial abstracts report no serious side effects, but they also give no safety data. The laser trial ran 12 weeks. Nobody has published a long-term safety study, for cosmetics or for injection.

For injection, there is no published human safety record for GHK-Cu on its own. The FDA cites concerns about immunogenicity from aggregation and impurities and notes limited human data. Repeated injection of a copper complex also adds copper to the body; nobody has measured what that does to copper balance over time.

So what holds up?

GHK-Cu has real laboratory science behind it: decades of cell and animal work, and a handful of small topical trials. But the published human evidence is thin. A systematic review found just two randomised trials in aesthetic medicine, and in the laser trial, blinded raters saw no difference. The gel that was tested as a wound medicine ended up cleared only as a device.

For injection, the picture is simpler. No published study has tested injected GHK-Cu on its own in people. What people believe about injecting it comes from animal work and from the assumption that a topical ingredient will work better from the inside. That assumption has not been tested.

Topically, the published trials report no serious side effects. Injected on its own, it has no published human data.

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