GHK Cu vs NAD+: Which Longevity Peptide Should You Take or Stack? If youre using GHK Cu and it stings a little (which is common) this ones for you , In this reel Im sharing the small tweaks that have helped me make peptide injections way more comfortable GHK Cu is a copper peptide known for supporting skin repair, collagen production, and overall tissue healing., Traditionally, its taken as an injection but that can come with irritation, bruising, or Mitigating GHK Cu Injection Pain: Tips and Tricks Gabriel Alizaidy, MD, MS posted on the topic LinkedIn