Imagine just wanting to be jacked and tan and you end up like this? Melanotan II is a peptide that increases the melanin in your skin and can give men a boner that Doctors Say "Barbie Drug" Melanotan II Can Cause Brain Swelling Synaptic changes induced by melanocortin signalling Nature Reviews Neuroscience 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 You Should Avoid Using Nasal Tanning Sprays