Why You Shouldnt Mix GHK Cu with AHA, BHA, or Retinol If youre using a GHK Cu (Copper Peptide) in your skincare routine, layering it with strong actives like AHA, BHA, or retinol may actually reduce Copper Peptides for Skin: What GHK Cu Does and How It Compares to Retinol Copper Peptides vs. Retinol & Vitamin C: What to Choose? by DrBeautiology Medium Why Collagen Loss Accelerates After 40: The Role of GHK Cu in Menopaus Pure & Cimple Retinoids vs Peptides (Matrixyl CP): what to pick + how to pair, Effectiveness: Retinoids (retinol tretinoin) have the strongest clinical data for photoaging (wrinkles, texture, tone). Peptides