What does Melanotan II do? Benefits and evidence

Melanotan II is an unapproved tanning peptide, sometimes used for libido. Individual reports describe changing moles, melanoma, prolonged erections and severe illness, but cannot prove it caused them or measure risk. Three small experiments enrolled 23 men. Online injections and nasal sprays have uncertain contents and strength.

• People report darker skin, often while using sunbeds or sunlight; tanning is not an approved use. (Reported by users)
• In two small trials of 10 men each, injections caused erections and more desire, though nausea was common. (Studied in a trial)
• In the first small study in people, injections darkened the skin and caused erections. (Studied in a trial)

Uses in the sources

• Community users report darker skin, often with sunbeds or sunlight. Cosmetic tanning is not an approved indication. (Reported by users) (source)
• Two small trials of 10 men each found erections after injection. They do not establish routine treatment or long-term safety. (Studied in a trial) (source)
• A 2026 phase 2 registration proposes use with NB-UVB for vitiligo. No results or usable dose schedule are posted. (Studied in a trial) (source)