Melanotan II

Melanotan II is sold online as a "tanning peptide," is not FDA-approved for any use, and has published case reports linking it to melanoma, dangerous mole changes, priapism requiring surgery, and other serious adverse events. Of everything covered on this site, this is the compound with the clearest documented real-world harm signal. This page describes what's known — not dosing or usage guidance, and not a recommendation to use it under any circumstances. Talk to a doctor, and see a dermatologist about any mole changes, immediately if you've used it.

Melanotan II is a synthetic analog of alpha-melanocyte-stimulating hormone (α-MSH), developed originally as a potential sunless-tanning and libido agent. It works by non-selectively activating melanocortin receptors, which stimulates melanocytes (the skin cells that also give rise to melanoma) to produce more melanin — the same pigment-producing pathway implicated in skin cancer biology. It's sold online as an unregulated "research chemical," explicitly labeled not for human consumption.

There is no completed large-scale human trial establishing safety for Melanotan II's marketed uses. What does exist is a growing body of published case reports directly documenting harm: melanoma diagnosed shortly after self-injected use (including in a 20-year-old woman after just 3–4 weeks of use combined with tanning-bed exposure), rapid eruption of new or changing moles that can mask early skin-cancer detection, priapism requiring surgical intervention, rhabdomyolysis, renal infarction, and posterior reversible encephalopathy syndrome (a serious neurological condition). Establishing direct causation from case reports alone has real limits — people using Melanotan II for tanning often also have high UV exposure independently — but this is documented human harm, not a theoretical concern, and the Skin Cancer Foundation and multiple national regulators have issued explicit public warnings about it.

The Skin Cancer Foundation — Warning Regarding Melanotan II →

Melanotan II has never been FDA-approved for any use, and its safety has not been established. It was among the peptides the FDA removed from its Category 2 "significant safety risk" compounding list effective April 22, 2026 — a technical change in nomination status, not a safety clearance — and it does not appear on the FDA advisory committee's list of peptides being considered for the actual compounding-permitted (Category 1) list. In practice, given its melanoma and other safety signals, Melanotan II is expected to remain effectively restricted from legitimate compounding-pharmacy access regardless of its Category 2 paperwork status. It is sold today only through unregulated online sellers, with no purity or dosing oversight.

FDA — Bulk Drug Substances Used in Compounding →

UNSW Newsroom — What Is Melanotan-II, the Drug Regulators Urge Consumers to Avoid?