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 Teen Boys and Young Men Are Injecting Peptides in Search of Perfection WSJ How Long Does It Take For Melanotan To Work? 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 Melanotan (MT) II Melanocortin Receptor Agonist MedChemExpress