Melanotan II is the product that's been dubbed the "Barbie drug" on social media, and promises to give users a tan without the sun but it can have serious side effects including, in rare cases, 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 Tanning News, Research and Analysis The Conversation page 1 A Current Affair: Tanning 'Barbie drug' a danger to users, experts say