GHK-Cu
GHK-Cu is the copper(II) complex of glycyl-L-histidyl-L-lysine, a tripeptide that occurs naturally in human plasma. Loren Pickart isolated it in 1973 after observing that a fraction of young human serum made liver tissue from older donors behave like younger tissue, work published in Nature New Biology that year. The free GHK peptide has a very high affinity for copper, and the bound complex is the biologically active form, which is why the compound is sold and dosed as GHK-Cu rather than as GHK alone.
- class
- copper-binding tripeptide (Gly-His-Lys complexed to Cu2+)
- sequence
- 3 amino acids, glycyl-L-histidyl-L-lysine
- route
- topical (best evidence); subcutaneous or intradermal in research use
- typical dose
- 1–2 mg/day subcutaneous; 0.05–0.2% (0.5–2 mg/mL) topical
- solution color
- deep blue, expected from the copper(II) complex, not contamination
- storage
- lyophilized cool and dark; reconstituted 2–8°C, 28-day max
GHK-Cu Reconstitution & Dosage Protocol
weekly dose · reduces side effects| Phase | Window | Weekly dose | Draw (U-100, 5mL BAC) | Note |
|---|---|---|---|---|
| Conservative start | Days 1–7 | 1.00 mg | 10 units· 0.10 mL | 1 mg once daily subcutaneous. At 10 mg/mL (50 mg vial in 5 mL BAC water) this is 0.1 mL, which is 10 units on a U-100 syringe. Stinging at the injection site is the most common complaint, so establish tolerance before moving up |
| Standard research range | Days 8–30 | 2.00 mg | 20 units· 0.20 mL | 2 mg once daily, which is 0.2 mL or 20 units at 10 mg/mL. This is the most commonly reported self-directed dose. Rotate sites, the copper complex is locally irritating and can leave a temporary blue-green mark |
| Upper anecdotal range | As tolerated | 3.00 mg | 30 units· 0.30 mL | 3 mg daily is the top of reported use and carries a real copper load. No human trial has established a safe systemic GHK-Cu dose, so this range rests on anecdote alone and is not appropriate for extended runs |
| Topical protocol | Ongoing | 1.00 mg | 10 units· 0.10 mL | Cosmetic and study formulations run 0.05% to 0.2%, which is 0.5 to 2 mg/mL, applied once or twice daily. This is a concentration rather than a systemic dose, and it is the route with actual published human skin data behind it |
| Off period | After 30 days | 0.00 mg | 0 units· 0.00 mL | Stop injectable use for 4 weeks. Copper is cumulative and is not cleared as fast as the peptide, so serum copper and ceruloplasmin are worth checking before any second cycle |
What is GHK-Cu?
GHK-Cu is the copper(II) complex of glycyl-L-histidyl-L-lysine, a tripeptide that occurs naturally in human plasma. Loren Pickart isolated it in 1973 after observing that a fraction of young human serum made liver tissue from older donors behave like younger tissue, work published in Nature New Biology that year. The free GHK peptide has a very high affinity for copper, and the bound complex is the biologically active form, which is why the compound is sold and dosed as GHK-Cu rather than as GHK alone.
Plasma GHK falls with age, from roughly 200 ng/mL around age 20 to about 80 ng/mL by age 60. That decline lines up with the decline in tissue repair capacity, which is the basis for most of the interest in supplementing it. GHK is also released locally when tissue is injured, where it acts as a signal that recruits repair machinery to the wound rather than acting as a hormone with a systemic target.
Mechanistically GHK-Cu does two things at once: it delivers copper, a required cofactor for lysyl oxidase and superoxide dismutase, and it signals directly to fibroblasts. Maquart and colleagues showed in 1988 that the complex stimulates collagen synthesis in fibroblast culture, and later work from the same group (J Invest Dermatol 2000) demonstrated modulation of glycosaminoglycan and small proteoglycan expression in healing wounds. It raises both matrix metalloproteinases and their inhibitors (TIMPs), which is the pattern of controlled remodeling rather than pure matrix accumulation, and Gruchlik and colleagues reported increased TGF-beta secretion in normal human dermal fibroblasts in 2014.
The broadest claim in the literature comes from gene expression profiling. Pickart's analysis using the Broad Institute Connectivity Map reported that GHK at 1 micromolar significantly changes expression of roughly 4,000 human genes, generally shifting them back toward a healthy pattern, and the 2015 and 2018 reviews build the antioxidant, anti-inflammatory, and tissue remodeling case on that dataset. This is a real and frequently cited finding, but it is cell culture transcriptomics rather than clinical outcome data, and it should be read that way.
Practically, the evidence gradient is steep: topical GHK-Cu has decades of cosmetic formulation work and published human skin studies behind it (a 2023 Pharmaceutics paper covers liposomal delivery specifically), while injectable GHK-Cu has no published human dosing protocol at all. There is no FDA approval for any indication and it is sold in the United States for research purposes only. The specific caution is copper: GHK-Cu carries copper into the body, it accumulates, and anyone with Wilson disease or another copper handling disorder should not use it at all.