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 Risks of Melanotan: TGA to issue fresh warning against 'Barbie drug' The Australian Viral 'Barbie drug' for tanning can cause brain swelling and even cancer, experts warn 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,