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 The Dark Side of Melanotan Tanning Injections: My Personal Experience Revealed How Long Does It Take For Melanotan To Work? Melanotan II Safety: Tanning Injection LIVV Natural Melanotan II A Sun Kissed Look, and a Confident You. Peptides for tanning do exist. Melanotan 1 and Melanotan 2 both work at increasing melanin in the skin. Melanotan 1 takes longer to activate. Melnotan 1 is FDA approved. Melanotan 2 does libido,