GHK Cu is a naturally occurring tripeptide in human plasma. Levels average 200 ng ml at age 20 and drop to 80 ng ml by age 60 (Pickart et al., 2020). That decline tracks with Copper peptides like GHK Cu work by sending signals to your skin to repair, regenerate, and produce collagen. It's not about instant results, it's about improving how your skin functions over time. Dr. Growth Hormone and Aging Endotext NCBI Bookshelf What is the safe topical dosing, duration, and contraindications for the copperbinding peptide GHKCu for wound healing or antiaging?