Melanotan II

Melanotan II is a lab-made, ring-shaped (lactam-bridged) peptide based on part of alpha-melanocyte-stimulating hormone (alpha-MSH), the hormone that signals skin to make pigment. Because it mimics alpha-MSH, it darkened skin in early studies but also caused spontaneous erections, nausea and less appetite. It is sold online without approval, mostly for tanning, which earned it the nickname “Barbie drug.”

In the small 1990s studies, nausea, stretching and yawning, less appetite and spontaneous erections were common, and one man had marked sleepiness and fatigue. Case reports add more serious problems: melanoma, a brain swelling disorder (PRES), an adrenaline-like toxic state, muscle breakdown with kidney injury, kidney infarction, and priapism that needed surgery. One person who injected it for 64 days developed brown patches on the gums and inside the cheeks; the cheek patches nearly faded within a month of stopping, but the gum pigmentation was still visible three months later. Priapism is an emergency: in one reported case, it needed surgery after other treatments failed.

It has not been proven, but there are warning signs. A 2017 review found four case reports of melanoma arising from existing moles during or shortly after melanotan use. In one, a 20-year-old woman with fair skin developed melanoma after 3 to 4 weeks of melanotan II injections combined with sunbeds. A 2025 report describes melanoma inside the mouth of a 22-year-old who used a melanotan II nasal spray. Even the label of the approved relative, afamelanotide, warns of darkening of existing moles and freckles and recommends a full-body skin exam twice a year. Show a dermatologist any new or changing mole.

No. Afamelanotide, sold as Scenesse, is a different alpha-MSH analog, first approved in the US in 2019. It is a 16 mg implant that a healthcare professional places under the skin every 2 months, approved only to increase pain-free light exposure in adults with a history of phototoxic reactions from erythropoietic protoporphyria (EPP). It is never sold as a vial you mix. Melanotan II has no approved use.

Melanotan II is not FDA-approved for any use. An FDA import alert for unapproved new drugs lists melanotan products that are imported as “non-human research” products and then sold online, and the FDA has told peptide sellers that “research use only” labels don’t stop products meant for people from being drugs. Melanotan II is in no category of the FDA’s lists for pharmacy compounding: it sat in Category 2, for substances with significant safety risks, until its nominators withdrew it. The FDA plans to discuss it with an advisory committee before the end of February 2027; no date is set.

Often not. A 2015 analysis of vials from three online shops, each sold as 10 mg, found 4.32 to 8.84 mg of melanotan II, and two shops’ vials held 4.1% to 5.9% unknown impurities. A forensic lab found a seized vial labeled melanotan II was 30% pure. A 2026 review lists melanotan II among unapproved peptides with risks of contamination, impurities and inaccurate dosing. The melanotan II 10 mg calculator can only work from the amount on the label, so its numbers are only as good as the vial.