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 Melanotan II (Tan Jabs): Why They're Not Worth The Risk Melanotanassociated melanoma Paurobally 2011 British Journal of Dermatology Wiley Online Library 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 What are the mechanism of action and side effects of Melanotan 2 (afamelanotide)? What is the 'Barbie drug' and should authorities be worried? ABC News