Dangerous 'Barbie drug' Melanotan II sparks crackdown on social media influencers ABC News Melanotan II in Santa Barbara, CA Eternity Health Partners It doesn't take much to fall down the Barbie Drug rabbit hole. In self tanner subreddits and on TikTok Shop, the tanning injectionaka Melanotan IIis marketed as a self tanner alternative that works by Melanotan II is a synthetic peptide that mimics the bodys natural melanocortin hormones, primarily activating receptors involved in skin pigmentation, appetite, and central nervous system signaling.