Melanotan II is a synthetic cyclic heptapeptide analogue of alpha-melanocyte-stimulating hormone (alpha-MSH) that non-selectively activates melanocortin receptors MC1R through MC5R. Originally developed for photoprotective skin tanning, it also affects sexual function (MC3R/MC4R) and appetite (MC4R). PT-141 (bremelanotide) was derived from MT-II research as its active metabolite responsible for sexual arousal effects. MT-II is not approved for human use in any country, and multiple regulatory agencies have issued explicit safety warnings against its use.
Category: Melanocortin Agonist. Evidence rating: F (anecdotal/unsupported).
Clinical status: Research-only / Not approved. Multiple regulatory warnings issued worldwide.
MT-II activates melanocortin receptors MC1R through MC5R non-selectively. MC1R activation stimulates melanogenesis (skin tanning) in melanocytes. MC3R/MC4R activation in the CNS increases sexual arousal and desire via dopamine release pathways. MC4R activation centrally suppresses appetite. The…
Research base: 1 registered clinical trial and 11 indexed publications reference Melanotan II.
Safety considerations: Nausea (very common, especially at initial doses); Facial flushing and warmth; Spontaneous erections (in males).
Reviewed by the PeptideAtlas Editorial Team. Last reviewed: 2026-07-05.
Related peptides: Afamelanotide.
Compare: Melanotan II vs Afamelanotide.
Multiple regulatory agencies worldwide have warned against its use. It is not approved for human use in any country. Risks include interference with melanoma detection, unpredictable mole changes, and unknown long-term effects on skin cancer risk.
No. Melanotan I (afamelanotide/Scenesse) is more selective for MC1R and is EMA-approved for erythropoietic protoporphyria (EPP). Melanotan II is non-selective across MC1R-MC5R and not approved for any use.
Yes. PT-141 (bremelanotide) is the active metabolite of Melanotan II that was isolated for its sexual arousal effects. It received FDA approval (Vyleesi) for female HSDD in 2019, while MT-II itself remains unapproved.
The long-term effects on melanocyte transformation are unknown. MT-II stimulates melanocyte activity and can cause new or changing moles, which complicates melanoma screening. This is a primary safety concern cited by regulatory agencies.
Yes. WADA prohibits all peptide hormones and growth factors not approved for human therapeutic use, which includes Melanotan II.