What it is
GHK-Cu is one of the smallest compounds in this library: a peptide of three amino acids, carrying a copper ion.
The peptide is GHK — glycine, histidine, lysine, in that order. It is not synthetic in origin. It occurs naturally in human blood plasma, and it is released from collagen when tissue is damaged. That observation is what started the interest: a fragment that appears exactly when the body is repairing itself looks, on the face of it, like a repair signal.
The Cu is a copper(II) ion held by the peptide. This part is not decorative. Copper is genuinely required by several enzymes that build and remodel connective tissue, and a small molecule that can carry copper into skin is doing something chemically real.
So the starting premise is respectable, which is worth saying plainly before the evidence section, because the evidence section is where this entry gets uncomfortable.
What it is said to be good for
Skin, mostly: wrinkles, firmness, elasticity, wound healing and hair. It appears in a great many cosmetic products and is sold separately as a research chemical.
What the research shows
There is a lot written about GHK-Cu. PubMed indexed 130 records on 2026-09-07 for the compound and its synonyms, 47 of them tagged as human research. Much of the most-cited material consists of reviews and laboratory studies of gene expression, collagen and tissue remodelling — real work, done carefully, in cells and animals.
There is one randomized controlled trial. Exactly one, out of those 130 records, is indexed as a randomized controlled trial: Miller and colleagues, Archives of Facial Plastic Surgery, July–August 2006. Thirteen patients completed it. They had circumoral skin resurfacing with a carbon dioxide laser and were randomised to aftercare with or without GHK-Cu products.
It was negative on every objective measure. In the authors' own words, the copper tripeptide products offered no significant reduction or resolution of post-treatment redness, and objective evaluation found no significant improvement in wrinkles or overall skin quality. Computer analysis and blinded evaluators both found no difference between the groups.
One result was positive, and it is worth reporting exactly rather than dismissing. On the patients' own validated questionnaire, satisfaction with overall skin quality was significantly higher in the GHK-Cu group (P = 0.04). Every patient in the study improved — laser resurfacing does that — but only the people using GHK-Cu rated the improvement higher.
A difference that a user reports and that a blinded evaluator and a computer cannot see is a real finding about perception. It is not a finding about skin. Both halves of that sentence belong in any honest account of this compound, and most accounts print only one of them.
What is being tested now. ClinicalTrials.gov returns three interventional studies for GHK-Cu, and two of them are not what they look like: one is a study of a facial treatment device, and one measures circulating GHK during use of an adhesive patch. One is filed as administering the compound: NCT07437586, a Phase 2 randomized, double-blind, vehicle-controlled split-wound study of a topical GHK-Cu gel, 60 planned participants.
Corrected 2026-09-08. An earlier version of this entry counted that registration as a trial in progress. Its sponsor, Hudson Biotech, has filed eight ClinicalTrials.gov registrations in total (registry API, 2026-09-08): all list one facility and start dates inside a two-week window in February 2026, and together they cover MOTS-c, BPC-157, TB-500, GHK-Cu, Melanotan II, tesamorelin, tirzepatide and retatrutide. Two of them carry Eli Lilly's own protocol identifiers — a registry search for I8F-MC-GPHK returns Lilly's completed tirzepatide study NCT04184622 alongside Hudson Biotech's filing, and J1I-MC-GZBF returns Lilly's completed retatrutide study NCT04881760 alongside Hudson Biotech's. None of the eight has posted results. This entry therefore does not treat that registration as evidence that a trial programme is under way. Peptifact's MOTS-c dosage reference sets out the full table of eight and how to reproduce the two identifier searches. So the honest position is that nothing is being tested that we can verify.
A note this library applies to every registry entry, and which matters more here than usual: a ClinicalTrials.gov record is a description written by the study's own sponsor. Nobody verifies it before it appears. It becomes evidence when results are published, and not before.
Why the evidence is thin when the ingredient is everywhere
The obvious question, once the trial count is on the table, is how a compound sold this widely for this long can have one small randomized trial behind it.
The answer is regulatory, and it is worth understanding because it applies to a great many things in this library. GHK-Cu is used as a cosmetic ingredient, and a cosmetic is held to a standard of safety and honest labelling. A drug is held to a standard of demonstrated effect, which means trials, endpoints and a regulator reading the results.
Nobody has had to run the trials, because nothing GHK-Cu is sold as has required them. Decades of use is evidence about safety and about commercial appeal. It is not evidence of effect, and it never accumulates into evidence of effect no matter how long it goes on.
The same regulatory route explains the library's other widely-sold tripeptide. All 57 US drug-database records for glutathione turn out to be homeopathic remedies and skin-whitening cosmetics — categories that reach a shelf without ever demonstrating an effect.
Where it stands
Approved as a medicine: nowhere.
Regulated as: a cosmetic ingredient, in the products most people encounter it in.
Randomized human evidence: one indexed trial, 13 completers, negative on every objective endpoint.
Available as: cosmetic products, and separately as a research chemical.
Related entries in this library: this entry answers what GHK-Cu is and what is known about it. Questions about which products contain it, or which are worth buying, are not questions this library answers.
Related entries in this library: argireline is the other widely sold cosmetic peptide, and its only rigorous trials were run by the NIH for an eye-muscle disorder rather than for wrinkles. The octapeptide marketed as a needle-free alternative has a smaller file still — two papers, neither of which isolates it from the other ingredients it was tested with.
Last checked
2026-09-07. The PubMed counts and the ClinicalTrials.gov records were retrieved on that date through the NCBI E-utilities and the registry API; the 2006 trial's methods and results are quoted from its published abstract.