Viral 'Barbie drug' for tanning can cause brain swelling and even cancer, experts warn 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 Gen Z adults appear more likely to tan, but experts warn of risks for UV exposure and 'viral' tanning trends KBIA Does Melanoboost work on fair skin?