GHK Cu Organic Serum Copper Peptide for Anti Aging & Skin Repair Topical or SubQ GHK Cu? Same molecule. Very different purposes. Topical you apply it on your skin. Think of it as feeding your skin from the outside. In a 12 week study of Dubai In Home GHK Cu Tripeptide Injection Book Private Therapy 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),