What is Melanotan II the drug that the TGA urges consumers to avoid? 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 Viral 'Barbie drug' for tanning can cause brain swelling and even cancer, experts warn White model Martina Big, who now a ''black' after taking tanning injections, announces plans to move to Africa.