Rise in use of 'dangerous' tanning injection Channel 4 News 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 People are injecting a tanning peptide to get darker skin without the sun., Its called Melanotan., It works by stimulating melanin production in the body but regulators have raised serious safety Your Guide to Melanotan II: What to Know Before Beginning Your Peptide Therapy