Brits buy 17 illegal 'Barbie' tanning injections that 'lead to kidney failure, brain swelling and hallucinations' 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 Fresh warning for 'Barbie drug' Medical Republic Figure 3 from The efficacy of afamelanotide and narrowband UV B phototherapy for repigmentation of vitiligo. Semantic Scholar