Why is the injection site painful after administering GHK Cu (Glycyl L Histidyl L Lysine Copper) 2mg mixed with normal saline? 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 Before you decide to begin using the copper peptide, GHK Cu, be aware it stings and leaves behind big, red welts that then leave a lovely bruise. In order to reap the 'glow' GHK Cu is a fantastic peptide but it can burn or bruise some people. Quick options to help reduce that issue. #ghk cu #copperpeptides #KLOW #GLOW #peptides