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 Thermodynamically stable ionic liquid microemulsions pioneer pathways for topical delivery and peptide application ScienceDirect GHK Cu: My secret weapon for skin, hair, and healing, I use it two ways topical cream for my face, and subQ injections 3x a week., It boosts collagen, tightens skin, helps hair grow, and even Ghk Cu Intra Nasal Spray 50 mg 0.34 oz. Westend Medical Supply