GHK-Cu (copper tripeptide, topical)

Tier 3 — weak evidence · Skin · Wound healing · Hair

A naturally occurring copper-binding tripeptide present in human plasma, with declining concentrations after age 50. Topical formulations have moderate evidence for wrinkle reduction, skin elasticity, and post-procedure recovery; smaller evidence for hair follicle health. Oral or injected use is not recommended for self-administration — copper toxicity risk and the same regulatory ambiguity as other peptides apply. Cosmetic-grade topical products are widely available.

Dose: Topical only: 0.1–2% serum or cream, applied 1–2× daily