JLE European Journal of Dermatology Eruptive naevi and darkening of pre existing naevi 24 h after a single mono dose injection of melanotan II 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 II Wikipedia Avoid nasal tanning sprays or nasal tanners entirely. These products promise an all over tan without sun exposure but they are unregulated, can be unsafe, and contain potentially risky substances like Melanotan 2.