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 DNA Code Botox Alternative Argireline Copper Peptide Wrinkle Reduce Serum Booster w Snap 8, Matrixyl 3000 Amazon.com: Skin Perfection Copper Peptide Serum GHK CU 1% for Face & Hair Copper Peptides for Skin, Hair, & Scalp 1% Blue Liquid for Face, Neck, Body, Scalp Multi Use Serum Booster with GHK Cu vs NAD+: Which Longevity Peptide Should You Take or Stack?