The adverse events reported in early studies and in case reports of unlicensed Melanotan II use, with the evidence tier of each, and what cannot be concluded from them.
"Melanotan 2 side effects" and "is melanotan 2 safe" are among the most searched phrases about the compound. This page sets out what the published record contains. It is a summary of reports, with their evidence tier, and it is not a safety assessment. Melanotan II is not a licensed medicine, so there is no pharmacovigilance database, no product information leaflet and no regulator-reviewed adverse event profile for it.
Three kinds of source exist.
None of these is a controlled trial of a defined product at a defined strength. The products in case reports were unlicensed, of unknown composition and unknown purity, which is the first limit on everything below.
The volunteer studies reported nausea, facial flushing, yawning and stretching, reduced desire to eat, and spontaneous penile erections in male participants. These are consistent with activity at MC3R and MC4R in the brain rather than at the skin receptor, which is why they are not reported for the more selective Melanotan I.
| Reported event | Source type | Causality |
|---|---|---|
| New or darkening moles (naevi) | Multiple case reports, dermatology | Plausible, consistent with MC1R activity |
| Melanoma diagnosed after use | A small number of case reports | Not established; association only |
| Priapism | Case reports | Plausible, consistent with MC4R activity |
| Raised blood pressure, nausea, vomiting | Case reports | Reported |
| Rhabdomyolysis, renal injury | Single case reports | Reported; confounded by other factors |
The melanoma reports deserve a specific note. A case report shows that two things happened to one person. It cannot show that one caused the other, and the number of reports is small. Dermatologists have raised the concern because melanocortin signalling drives melanocyte activity and because changed moles are a known finding. The question is unresolved, which is different from answered either way.
The identity, structure and receptor profile of the compound are on the Melanotan II identity page, and the comparison with the licensed, selective analogue is in Melanotan I vs Melanotan II. The catalogue item is the Melanotan II 10mg research vial.
Materials sold on this site are supplied solely for non-clinical in-vitro laboratory research. They must not be ingested, injected, inhaled, applied or otherwise administered to a human or animal.
We do not provide dosing, routes of administration, treatment guidance, cosmetic-use guidance or in-vivo protocols. Preparation, storage and handling must follow a validated institutional SOP, the material documentation and an appropriate risk assessment.
What Melanotan II is, how it relates to alpha-MSH, which melanocortin receptors it binds, and why it has never been a licensed medicine anywhere.
Research DocumentationOne is linear, selective and a licensed medicine under another name. The other is cyclic, non-selective and never licensed. The structural and regulatory differences explained.
Site materials are supplied solely for non-clinical in-vitro laboratory research. They must not be used in or on humans or animals. We do not provide dosing, routes of administration, treatment, cosmetic-use or in-vivo guidance. Read the legal and research-use terms.