Melanotan 2 Cyclic Heptapeptide for Melanocortin Research Melanotan 2 Day 4: Whacky Side Effects. , I am cutting back from daily use and probably using once a week from here on out. , Zero appetite, Fatigue, And what I think was sleep paralysis , And yes 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 What are the mechanism of action and side effects of Melanotan 2 (afamelanotide)?