Product Question] Most effective way to deliver GHK Cu (Copper Tripeptide 1) through skin? : r SkincareAddiction GHK Cu vs NAD+: Which Longevity Peptide Should You Take or Stack? Mitigating GHK Cu Injection Pain: Tips and Tricks Gabriel Alizaidy, MD, MS posted on the topic LinkedIn For subcutaneous injections, using shorter needles (4 5mm) is the safest choice to ensure medication stays in the fatty layer and avoids muscle injury. A 4mm needle is ideal, minimizing pain while keeping Amazon.com: Skin Perfection Copper Peptide Serum GHK CU 1% for Face & Hair Copper Peptides for Skin, Hair, & Scalp 1% Blue Liquid for Face, Neck, Body, Scalp Multi Use Serum Booster with