GHKCU Skin Transformation Results After 4 Weeks A Dermatologist's Take on the Copper Peptide (GHK Cu) Trend 12 weeks in, and my skin has NEVER looked better! GHK peptides are doing their thing. Alright, I need to give you an updateit's been 12 weeks since I started using GHK 12 weeks in, and my skin has NEVER looked better! GHK peptides are doing their thing. Alright, I need to give you an updateit's been 12 weeks since I started using GHK 30 Days Before & After Copper Peptide Serum Copper peptides arent just anti aging theyre skin quality essentials. No matter your age, strong skin = better texture, elasticity, and resilience.