Synthetic cyclic melanocortin analog (non-selective MC receptor agonist)
An unapproved synthetic peptide sold online to darken skin ('tanning') and boost libido.
| Class / type | Synthetic cyclic melanocortin analog (non-selective MC receptor agonist) |
|---|---|
| Category | Sexual, Skin & Aesthetic |
| Status (Jul 2026) | Research use only |
Melanotan II is a synthetic peptide sold online (illegally, for human use) to produce a tan with less sun exposure and to increase libido. It's a non-selective melanocortin-receptor agonist.
It is not approved anywhere for these uses. Its MC4R (arousal) activity is notable because it inspired the development of the FDA-approved libido drug bremelanotide (PT-141).
It activates several melanocortin receptors: MC1R stimulates melanin production (tanning), while MC4R in the brain drives sexual arousal and appetite changes. The broad, non-selective activity is what produces both the tanning and the side effects.
There are no approval-grade efficacy or safety trials for its tanning/libido use. What exists is largely case reports and small studies, plus the indirect validation that its MC4R mechanism led to an approved drug (bremelanotide).
Users report rapid, deep tanning with less UV exposure and increased libido and spontaneous erections.
On-demand arousal effects that work for both men and women are commonly cited.
Nausea and flushing are common. More concerning: darkening and changes to moles, new or atypical nevi, and case reports of melanoma, as well as priapism (prolonged erection), rhabdomyolysis and renal events.
The supply is entirely unregulated, so purity, dosing and contamination are real hazards. Anyone using it should have moles monitored by a dermatologist.
Not FDA-approved and illegal to sell for human use; shipments are subject to seizure. Those seeking the libido effect specifically may be better served by the approved, studied alternative PT-141 (for its labeled use).
Popular in tanning and bodybuilding circles for effectiveness, but many report unpleasant nausea and worry about mole changes.
NOT FDA-approved for any use; an unapproved new drug that is illegal to sell for human use, with import shipments subject to seizure.