GHK Cu (copper peptide) used topically is one of the most well studied skin repair peptides. Here's how it helps the skin, in practical terms: 1. Boosts collagen & elastin GHK Cu signals your skin Copper Peptides Before and After: Visible Skin Improvements Explained Hubmed Rosacea isn't just about rednessit's often a sign of a compromised skin barrier and ongoing inflammation. When the barrier is weakened, skin becomes more reactive: Increased sensitivity Higher transepidermal water Treating Skin With Azelaic Acid: Before And After SkinLab