Before and after Melanotan tanning therapy, sunless tanning results Health expert says Melanotan II darkens skin moles and can make melanoma hard to detect Herald Sun Nasal tanners claim to work by using Melanotan II, a chemical that darkens skin pigmentation. It is illegal to sell medicinal products containing Melanotan II in the UK but since the tanners are sold 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