Nobody has been able to establish a lethal dose (LD50), even at concentrations way beyond what's used in typical protocols
GHK-Cu stimulates collagen and elastin at the gene expression level without causing irritation, and it actually helps repair UV damage rather than increasing UV sensitivity
References Monnier M, Dudler L, Gchter R, Maier PF, Tobler HJ, Schoenenberger GA
But because of its named source, it can be more traceable than L-glutathione
Peptides provide several benefits , including increased muscle growth, improved fat metabolism, enhanced recovery, better skin health, and cognitive support