Peptides vary by type, so lab testing and medical supervision matter
It appears to bind to p53 and thereby may prevent apoptotic death of the senescent cells
"Analytical approaches for the detection of emerging therapeutics and non-approved drugs in human doping controls." Journal of pharmaceutical and biomedical analysis 101 (2014): 66-83
This particular peptide promotes tissue repair by boosting blood vessel growth and collagen production, which helps mend muscles, tendons, ligaments, bones, and skin faster
Reported issues, usually mild, include redness, itching, or contact sensitivity, particularly when GHK-Cu is combined with strong actives like retinoids or exfoliating acids