Fresh warning for 'Barbie drug' Medical Republic 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, 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 Ocular Melanosis Melanotan peptide might seem like the cool thing to doit makes you look tan., But these unregulated injections come with real risks., They can cause unpredictable skin changes, including darkening of Changes in Oral Mucosa Associated with Melanotan II Injections: A Case Report