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 Doctors have warned people not to use so called 'Barbie Doll' tanning injections bought over the internet Irish Mirror Barbie drug' nasal spray tan plugged by influencers causes cancer, doctors warn Experts lash use of popular social media sun tanning drug Melanotan