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 What are the recent findings on the safety and efficacy of melanotan for therapeutic and cosmetic use? Melanotan II (Tan Jabs): Why They're Not Worth The Risk Viral 'Barbie drug' for tanning can cause brain swelling and even cancer, experts warn