What Is Melanotan-2 and How Does It Work
Melanotan-2 (MT-2) is a synthetic 7-amino-acid cyclic peptide analog of alpha-melanocyte-stimulating hormone (alpha-MSH), the natural hormone that regulates melanin production in the skin. It was developed at the University of Arizona in the 1980s as a candidate for sunless tanning and photoprotection research. Unlike more modern, receptor-selective melanocortin peptides, Melanotan-2 is a non-selective agonist - it activates multiple melanocortin receptor subtypes at once: MC1R (which drives eumelanin production and skin darkening), MC3R, MC4R (associated with appetite suppression and central sexual arousal pathways), and MC5R.
That lack of receptor selectivity is the mechanistic reason Melanotan-2 produces such a broad, and sometimes unpredictable, effect profile - tanning, appetite suppression, and increased libido or spontaneous erections can all show up in the same person, along with off-target effects like nausea and flushing. This is also the reason Melanotan-2 is not the same compound as PT-141 (bremelanotide): PT-141 was later derived from Melanotan-2 specifically by modifying it to act more selectively at MC4R, reducing the tanning and off-target activity while preserving the arousal-related effect. See the PT-141 (Bremelanotide) reference for that distinction in full.
Research Dosing
Dosing below reflects a mix of early human pharmacology research and long-standing research-community convention, not personal medical guidance and not a validated clinical dosing regimen. Melanotan-2 has never gone through an FDA dose-ranging program.
| Phase | Dose (commonly cited) | Frequency | Route |
|---|---|---|---|
| Loading / titration | ~0.1–0.25mg, escalating to 0.5mg | Daily, titrated over 1–3 weeks | SubQ injection |
| Maintenance | ~0.5–1mg | 2–3× weekly | SubQ injection |
Context: An early phase-I human study by Dorr et al. used escalating doses from roughly 0.01 to 0.03 mg/kg body weight, dosed daily on a Monday-through-Friday schedule. Research-community loading/maintenance conventions descend from that early pharmacology work combined with years of informal use-pattern reporting, not a completed controlled dosing trial.
Regulatory Status
Melanotan-2 is not FDA-approved for tanning, appetite suppression, libido, or any other indication, and it is not currently listed on the FDA's 503A or 503B bulk drug substance lists for compounding pharmacies. Products sold as "Melanotan-2" or "MT-2" are marketed as research chemicals for laboratory research use only, not for human consumption. Multiple international regulators, including agencies in the UK and Australia, have separately issued public warnings over the years about Melanotan products sold illegally as tanning injections outside any regulated supply chain. Purchasing a product labeled "research use only" carries no assurance of purity, accurate dosing, or safety evaluation by any regulator.
Safety Considerations
Melanotan-2's safety profile is a meaningful part of why it has been superseded, for arousal-related research, by the more selective PT-141/bremelanotide. Commonly reported effects include nausea and facial flushing, particularly during dose escalation, along with injection site reactions and spontaneous erections in male users. More serious concerns are documented in the case-report literature: rapid darkening or growth of existing moles, new nevus (mole) formation, and rare reports connecting use to melanoma and to systemic toxicity including rhabdomyolysis. Because Melanotan-2 stimulates melanocyte activity broadly, changes in pigmented lesions can also make visual skin-cancer screening more difficult to interpret. Anyone with a personal or family history of atypical moles or melanoma should treat this as a significant consideration, and regular dermatological monitoring is a reasonable precaution for anyone considering it.
What Research Shows
The foundational human data on Melanotan-2 comes from an early pilot phase-I clinical study in a small number of male volunteers, which established the tanning, appetite-suppressing, and libido-related pharmacology, along with an initial dose range. Beyond that early pharmacology work, most of the available human evidence on Melanotan-2 specifically is observational or case-report level - documenting both intended effects and the mole/melanoma-related adverse events described above - rather than large randomized controlled trials. That is a meaningfully thinner evidence base than exists for its FDA-approved descendant compound, bremelanotide.