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 Sexual dimorphism in the development and function of the melanocortin system Reviews in Endocrine and Metabolic Disorders Springer Nature Link Peptides are having a moment, but not all of them are harmless., One thats getting a lot of attention right now? Melanotan II., Its being used to achieve a tan from the inside, but what it Melanocortins and Their Potential for the Treatment, Prevention and Amelioration of Complications of Diabetes Suntan Drug Greenlighted for Trials WIRED