What it is
GHK-Cu is a small three-amino-acid peptide (glycine-histidine-lysine) naturally bound to a copper ion. It was first isolated from human blood plasma in 1973. Like several compounds here, its natural levels decline with age. It is the most established compound in this library for skin, with decades of cosmetic research behind it and routine use in commercial skincare.
How it works
GHK-Cu is a signalling molecule. In skin it stimulates production of collagen, elastin and glycosaminoglycans (the structural and water-holding components of the dermis), supports wound healing, and influences the activity of enzymes that remodel tissue. Copper itself is a cofactor for several skin-repair enzymes, which is thought to enhance its activity. Some research suggests it can influence gene expression toward a "younger" pattern.
What the evidence shows
The strongest human evidence is topical and cosmetic. Multiple controlled studies have measured real improvements in skin.
- A controlled trial in women found GHK-Cu eye cream outperformed both placebo and vitamin K cream for reducing lines and improving skin density and thickness.
- In a comparison against vitamin C and retinoic acid, topical GHK-Cu produced collagen increases in a majority of volunteers.
- Strong supporting evidence comes from animal and cell wound-healing models, where it consistently boosts collagen synthesis, angiogenesis and wound closure.
Topical vs injectable
This distinction matters. GHK-Cu's good reputation rests almost entirely on topical cosmetic use, where it is well established and generally regarded as safe at typical concentrations (around 0.2–2%). The injectable use promoted in some peptide circles is a different proposition with far less human evidence and falls into research-only territory.
Where it stands
As a topical cosmetic ingredient, GHK-Cu is legitimate, widely used and supported by human data, the clear standout in this library for evidence quality in its intended use. Claims about injected GHK-Cu, or systemic anti-aging effects beyond the skin, are far less supported.