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 Melanotan What It Is and Its Relation to Skin Cancer Melanotan II (Tan Jabs): Why They're Not Worth The Risk 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 medAge Aesthetics & Wellness