GHK-Cu, the copper peptide: what the studies measured and what they did not
· Novatheris
GHK-Cu is a very small peptide, just three amino acids long, that circulates in human plasma bound to a copper atom. It is one of the most talked-about compounds in skin and connective tissue research, and also one of the most quoted with figures no one can trace. Here is what has been published, with its source, and what has not.
What GHK-Cu is: the copper peptide from plasma
GHK stands for its three amino acids: glycine, histidine and lysine. "Cu" is copper, the metal's chemical symbol. The tripeptide binds copper in a 1 to 1 ratio and forms a complex.
The basic numbers:
- Sequence: Gly-His-Lys, complexed with Cu(II).
- Formula of the complex: C14 H21 Cu N6 O4, about 401 Da.
- Tripeptide alone, without the metal: C14 H24 N6 O4, 340.4 Da.
Loren Pickart described it in 1980. His work showed that the tripeptide exists in human plasma, that it associates with copper and iron, and that in culture those metal complexes stimulated adhesion and growth of hepatoma cells (Pickart and Thaler, 1980).
One piece of context worth keeping in mind: many of the reviews that promote GHK-Cu are written by the same person who first described it.
What was seen in animals
The strongest animal study is from 1993. In rats with wound chambers placed under the skin, the copper complex increased the buildup of collagen and other connective tissue components, with an effect that depended on the amount applied (Maquart et al., 1993).
A 2015 paper tested it in the rat knee, after anterior cruciate ligament reconstruction, in 72 animals. The treated group did better at 6 weeks. By 12 weeks that difference was gone (Fu et al., 2015). The authors themselves use the word "transiently" in the title.
It is a good example of why the moment you measure can change the conclusion.
The two human trials
Here GHK-Cu has something many research peptides lack: randomized trials in people. There are two, both topical, meaning applied to the skin. And both came out negative on what they set out to measure.
The first, in venous leg ulcers, had 86 evaluable patients and an evaluator who did not know who got what. The copper complex cream was no better than the placebo cream, and silver sulfadiazine, a standard treatment, beat both (Bishop et al., 1992).
The second, in skin treated with CO2 laser, had 13 patients who completed it. Computer analysis and blinded evaluators found no difference in redness and no objective improvement in wrinkles or skin quality. The only thing that differed was the satisfaction patients reported themselves (Miller et al., 2006).
Coming out negative in two trials does not rule a compound out forever. It does mark a wide gap between what gets said and what was measured.
Nothing injected in people
All published human evidence is topical. The injection data come only from rats: under the skin in wound chambers and inside the knee.
There is not a single published study of GHK-Cu injected in people. A 2026 review for sports medicine physicians puts it this way: indications, amounts, frequency and duration remain unknown (Mayfield et al., 2026).
How much crosses the skin
That is not settled either. The complex is hydrophilic, meaning it gets along with water and poorly with the fatty layers of the skin. So its passage through the stratum corneum, the outermost layer, is limited.
A 2025 paper on GHK-Cu inside liposomes, tiny fat bubbles used to carry molecules, argues there is not even a settled analytical method to measure how much gets in (Ogórek et al., 2025). And a review from the same year on topical GHK describes a surprising absence of clinical studies (Mortazavi et al., 2025).
The plasma figure no one can cite
Commercial material keeps repeating that plasma GHK falls from about 200 ng/mL at age 20 to about 80 ng/mL at age 60. We searched PubMed for the original study behind that measurement and could not find it.
What is published and verified is the 1980 work: GHK exists in human plasma and binds copper and iron. The figure for the drop with age has no support we can cite, so we do not use it.
What is still unknown
For the notebook:
- There is no published half-life, in humans or animals.
- Both randomized human trials were negative on their goals.
- There is no study in people with injected GHK-Cu.
- The effect in the rat knee was temporary.
- There is no settled method to measure how much crosses the skin.
How it is stored
GHK-Cu comes lyophilized, which means dry: a powder whose water was removed with cold and vacuum. That powder usually looks blue, because of the copper.
It is kept at -20 °C, closed and away from bright light. Let the vial reach room temperature before opening it, so moisture does not get in. Once reconstituted, it goes to 2 to 8 °C and for a short time.
Where to find it
GHK-Cu is also one of the four components of KLOW, a blend that has its own article and its own page.
If you need it for your research, the GHK-Cu page has its chemical data, the storage note and the purity information, with the +99.5% standard we ask of outside laboratories such as Janoshik and Freedom Diagnostics. Delivery takes 2 hours in the GAM and 24 hours in the rest of Costa Rica. For research use only.