Tanning, fake tan and Melanotan Cancer Research UK Viral 'Barbie drug' for tanning can cause brain swelling and even cancer, experts warn Viral 'Barbie drug' for tanning can cause brain swelling and even cancer, experts warn 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 longer lasting than Tanning Nasal Spray: Should You Skip It?