Rejuvenation and Youth with GHK Cu Peptide Treatment Dr. Ahmet zyigit Copper Peptides (GHK Cu): Benefits and Side Effects 7 days on GHK Cu. Here's my honest update. I'm not going to hype this up because the real results don't even start until week 46. But something is already happening. 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 The Effect of the Human Peptide GHK on Gene Expression Relevant to Nervous System Function and Cognitive Decline