What Is Melanotan II?
Melanotan II is a synthetic cyclic peptide that broadly activates melanocortin receptors, sold on the grey market as an unlicensed injectable “tanning” and libido product — it is not approved as a medicine or a dietary supplement anywhere. It is chemically related to the approved photoprotection drug melanotan I (afamelanotide) and to the approved libido drug bremelanotide (PT-141, which is a melanotan II metabolite), but melanotan II itself has never passed regulatory review. It stimulates melanin production (darkening skin) and can trigger erections and appetite suppression. Regulators including the UK MHRA and dermatology bodies have warned against it; this entry documents it because it is widely used, not because it is endorsed.
Evidence
There are no adequate randomised efficacy or safety trials establishing melanotan II as safe for tanning or libido, and the informative human literature is dominated by adverse-event case reports rather than controlled studies. Published cases and reviews describe priapism (prolonged, painful erection requiring intervention) 1Reference 1Case reportMelanotan Tanning Injection: A Rare Cause of Priapism — case reportView study →, along with nausea, flushing, blood-pressure changes, and — in the broader literature summarised by dermatology sources — reports of new or changing atypical moles and concern about melanoma, plus at least one report of systemic toxicity with rhabdomyolysis after overdose 2Reference 2ReviewMelanotan II — review (adverse effects: pigmented lesions/melanoma concern, systemic toxicity)View study →. The mole/melanoma link is a genuine documented concern rather than a proven causal effect, but combined with the mechanism (stimulating pigment cells) it is taken seriously by dermatologists. I did not find any credible trial showing it is safe.
Dosage & Safety
There is no established safe dose — melanotan II is unapproved, and grey-market product is unregulated, often bacteriostatic-water-reconstituted powder of unverified purity and sterility (injection also carries infection risk). Documented harms include priapism 1Reference 1Case reportMelanotan Tanning Injection: A Rare Cause of Priapism — case reportView study →, nausea and blood-pressure changes, rhabdomyolysis and systemic toxicity in overdose 2Reference 2ReviewMelanotan II — review (adverse effects: pigmented lesions/melanoma concern, systemic toxicity)View study →, and concern about changing/atypical moles and melanoma flagged by dermatology authorities. It is not a legal supplement or medicine and is not recommended for use; anyone using it who notices a changing mole should seek medical review. Interactions, long-term and pregnancy safety are not established. Informational only — this is not an endorsement or medical advice.
References
- Habeeb A et al. (2021). Melanotan Tanning Injection: A Rare Cause of Priapism — case report. Urol Case Rep. https://pmc.ncbi.nlm.nih.gov/articles/PMC7930850/
- DermNet NZ. Melanotan II — review (adverse effects: pigmented lesions/melanoma concern, systemic toxicity). https://dermnetnz.org/topics/melanotan-ii