GHK Cu vs NAD+: Which Longevity Peptide Should You Take or Stack? 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 GHK CU 50mg Vial Copper Peptide Pure Bio Labs Redness after a peptide injection can feel alarming but in most cases, it's completely normal. If you've noticed a pink or red halo at the injection site especially with peptides like GHK Cu 50mg Third Kind