Viral 'Barbie drug' for tanning can cause brain swelling and even cancer, experts warn 4 reasons to be cautious about melatonin Grand Strand Physicians 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 Melatonin for Sleep: Does It Work? Johns Hopkins Medicine