Melanocortin receptor agonist · Also known as MT-2, MT-II, Melanotan 2
A synthetic analog of alpha-melanocyte-stimulating hormone that stimulates melanin production for skin tanning, while also affecting sexual arousal and appetite. Not approved for human use in any country and carries notable safety concerns.
Melanotan II was developed at the University of Arizona as a potential preventive agent against skin cancer by stimulating the body's natural tanning response without UV exposure. However, it was never approved for clinical use due to its nonselective activity across multiple melanocortin receptors, leading to a wide range of effects and side effects. It remains widely used in underground markets for cosmetic tanning despite regulatory warnings from the FDA, EMA, and TGA. Case reports have documented serious adverse events including rhabdomyolysis and renal infarction.
Melanotan II binds nonselectively to melanocortin receptors MC1R, MC3R, MC4R, and MC5R. Its tanning effect comes from MC1R activation on melanocytes, which triggers the cAMP signaling cascade, activates protein kinase A, and stimulates transcription of enzymes involved in melanin synthesis (tyrosinase and related proteins). This produces a tan without requiring UV exposure, though UV exposure accelerates the effect.
Its sexual arousal effects are mediated through MC4R activation in the hypothalamus, the same pathway exploited by PT-141 (which was derived from Melanotan II). MC3R and MC4R activation in the brain also suppresses appetite and affects energy homeostasis. Because Melanotan II crosses the blood-brain barrier and hits multiple receptor subtypes nonselectively, it produces a broader and less predictable range of effects than more targeted melanocortin drugs.
100-250 mcg/day
First few days (to assess tolerance)250-500 mcg/day during loading, then 250-500 mcg 1-2x/week
Loading: 2-3 weeks; maintenance: ongoingMost side effects tend to improve as your body adjusts.