Experts lash use of popular social media sun tanning drug Melanotan Your body already makes a hormone that tells your skin to tan. Melanotan 2 is a synthetic peptide engineered to mimic that hormone but in a version that's more potent and longer lasting than Melanotan is trending again. As a dermatologist, I strongly need to tell you , Its an unapproved injectable peptide, and were seeing:, nausea and flushing, darkening of existing moles, Melanotan What It Is and Its Relation to Skin Cancer