GHK Cu Copper Peptide: The Ultimate Peptide For Longevity Copper peptide questions we get asked all the time How often should you use it? Do you need to avoid the sun? If you're new, start once daily (evenings are great), How long will a 50 mg supply of GHKCu last when dosing 2 mg daily for five consecutive days followed by two days off each week? How long does it take GHK Cu to work? Entera Skincare