What GHK-Cu is
GHK-Cu is a tripeptide (glycyl-L-histidyl-L-lysine) that binds copper. It was isolated from human plasma in 1973 and is present in saliva and urine too. Levels drop steadily with age, from about 200 ng/mL at 20 to around 80 ng/mL at 60, which is one reason it attracted research as an anti-aging molecule.
What it does on the skin
- Signals repair. GHK-Cu activates genes involved in tissue remodelling. In fibroblast studies it increases collagen, elastin, glycosaminoglycans and decorin, the building blocks of firm, elastic skin.
- Supports healing. It has been studied for wound healing since the 1980s and is used in post-procedure formulas for that reason.
- Calms and protects. It has anti-inflammatory and antioxidant activity, so it does not trade renewal for irritation the way retinoids often do.
What the evidence looks like
The cellular and wound-healing evidence is strong and consistent. The cosmetic evidence in humans is smaller and mostly from industry-sponsored studies: 12-week trials on GHK-Cu creams report improvements in skin density, thickness, fine lines and elasticity, with very good tolerance. It is fair to say copper peptide is well supported for skin repair and firmness, and less proven than retinoids for deep wrinkles. For sensitive skin, that trade is usually worth it.
Copper peptide vs retinol
Retinol works by speeding up cell turnover, which is why it causes dryness, peeling and sun sensitivity, especially on reactive skin. GHK-Cu works by signalling repair without forcing turnover. It can be used morning or night, does not photosensitize, and can be started at full frequency. If your skin has never tolerated retinol, copper peptide is the place to start.
How to use it and what to avoid
Apply to clean skin, then moisturize. It layers well with hyaluronic acid, niacinamide and resveratrol. Two cautions: do not use it in the same step as a high-strength L-ascorbic acid serum (the acid can interfere with the copper complex; use vitamin C in the morning and peptides at night), and avoid combining it with strong acid exfoliants in the same routine. The gentle vitamin C in Nihon (sodium ascorbyl phosphate) is used in the morning, so it fits.
How IKI uses it
Izumi Skin Regenerating Serum combines copper tripeptide-1 with multi-weight hyaluronic acid, niacinamide, resveratrol and a low level of lactic acid, in a creamy night serum with no retinol and no fragrance. In its independent 30-day study on 46 people with sensitive skin, 93% said the serum felt gentle, 87% said their skin looked more glowing and 76% noticed plumper skin.
