F tier · safety concern
Abandoned in development, unapproved in every jurisdiction, and carrying published case reports of melanoma, melanoma in situ, eruptive dysplastic naevi, rhabdomyolysis and priapism in users.
melanotan ii
Melanotan II is a cyclic heptapeptide alpha-MSH analogue that stimulates melanogenesis and is sold illicitly as a tanning injection, having been abandoned in formal development. It is unapproved everywhere, has attracted formal warnings from regulators in the US, UK and Australia, and is associated with published case reports of melanoma and other serious harms.
the explanation
Melanotan II is an unlicensed injectable sold online to make people tan without sun exposure. It was dropped by its developers, no regulator anywhere permits it, and doctors have published cases of melanoma, sudden new moles, muscle breakdown and painful prolonged erections in people who used it.
regulatory status
Unapproved and warned against by multiple regulators
Melanotan II is not licensed for human use in any jurisdiction and has drawn explicit consumer warnings from the FDA, UK MHRA and Australia's TGA; the structurally related MC1R-selective agonist afamelanotide was approved in 2019 for erythropoietic protoporphyria, but Melanotan II itself was abandoned by Clinuvel over safety and regulatory concerns. FDA has scheduled a Pharmacy Compounding Advisory Committee meeting before the end of February 2027 to consider whether this substance should be added to the section 503A bulks list. A committee recommendation is non-binding and confers no approval; implementation would require notice-and-comment rulemaking, which the FDA bar estimates at twelve to twenty-four months or longer.
how it works · proposed mechanism
Melanotan II activates the melanocortin receptor family non-selectively, which is precisely why its effects extend well beyond pigmentation.
MC1R drives pigmentation
Agonism at MC1R on melanocytes stimulates eumelanin synthesis, producing tanning without ultraviolet exposure. This is the effect users seek, but it is inseparable from the compound's other receptor activity.
MC3R and MC4R side effects
Non-selective activity at MC3R and MC4R produces the reduced appetite, nausea and spontaneous erections that accompany use. Priapism has been documented as a genuine clinical emergency in the literature.
Stimulates melanocyte activity
The same melanocyte stimulation that darkens skin also darkens existing moles and is associated with eruption of new melanocytic naevi. Dermatologists regard this as obscuring the visual cues used to detect melanoma early.
Unregulated supply adds risk
Because all supply is grey-market, products carry risks of contamination, non-sterility and incorrect reconstitution independent of the peptide's own pharmacology. Needle sharing has been noted as an additional documented hazard.
what’s reported
evidence shape
6 sourcesThe composition of the cited literature by study type. This describes the shape of the evidence, not its quality — and it does not by itself set the grade.
⚠ the catch
The published melanoma and dysplastic naevi case reports are the decisive problem: invasive melanoma (Dermatology, 2014), melanoma in situ (Australasian Journal of Dermatology, 2012) and eruptive dysplastic naevi have all been reported in Melanotan II users, and the compound simultaneously darkens existing moles in a way that masks the visual warning signs clinicians rely on. There is no offsetting efficacy evidence to weigh against this, because no regulator anywhere has ever judged the compound's benefit-risk acceptable and its development was abandoned.
key published findings
- Human case report: invasive melanoma associated with the use of melanotan-II (Dermatology, 2014)
- Human case report: melanotan-associated melanoma in situ (Australasian Journal of Dermatology, 2012)
- Human case series: eruptive dysplastic naevi and eruptive melanocytic naevi following melanotan injection, including darkening of preexisting naevi within 24 hours of a single dose (Journal of the American Academy of Dermatology; British Journal of Dermatology)
- Human case report: melanotan tanning injection as a cause of priapism, a urological emergency (Sexual Medicine, 2021)
- Human review: systematic review of the risks of unregulated use of alpha-melanocyte-stimulating hormone analogues catalogues melanoma, naevus change, rhabdomyolysis and systemic toxicity (International Journal of Dermatology, 2017)
- Human case report: melanotan II injection resulting in systemic toxicity and rhabdomyolysis (Clinical Toxicology, 2013)
limitations of the evidence
- The harm evidence is case reports and case series, which establish association and biological plausibility but cannot quantify absolute risk or prove causation
- No controlled trial of Melanotan II has ever been completed, so there is no denominator of exposed users against which to calculate incidence of any adverse outcome
- No human pharmacokinetic data, no established half-life, and no dose-response characterisation exist in the accessible literature
- Eight ClinicalTrials.gov records naming research peptides — including BPC-157, TB-500, MOTS-c, GHK-Cu and melanotan II — share one sponsor, Hudson Biotech, and one site. A July 2026 investigation established that all eight are fabricated: at least two declare themselves fictional or mock in their own text, and two reproduce an Eli Lilly protocol design and compound code that Eli Lilly states it never authorised. The records were still listed as recruiting after the investigation was published. A registry entry is a form submission, not peer review, and this index does not treat one as evidence.
documented safety signals
- Invasive melanoma reported in users (Dermatology, 2014)
- Melanoma in situ reported in users (Australas J Dermatol, 2012)
- Eruptive dysplastic and melanocytic naevi, plus darkening of preexisting naevi, reported within 24 hours of a single dose
- Rhabdomyolysis with systemic toxicity — potentially fatal muscle breakdown
- Priapism requiring urological intervention
- Posterior reversible encephalopathy-type syndrome reported
- Nausea, vomiting, facial flushing and appetite suppression as routine effects
- Contamination, non-sterility and needle-sharing risks inherent to grey-market supply
- Darkening of moles obscures the visual criteria used for early melanoma detection
identity
| full name | Melanotan II |
| category | Cosmetic |
| modality | peptide |
| formula | C50H69N15O9 |
| molar mass | 1024.2 g/mol |
| cas | 121062-08-6 |
| sequence | Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2 |
laboratory handling
| storage | Lyophilised powder stable at -20°C protected from light; reconstituted solution refrigerated at 2-8°C and protected from light, though no pharmaceutical-grade stability data exist because no licensed product is manufactured. |
| solubility | Soluble in sterile or bacteriostatic water; the cyclic peptide dissolves readily in aqueous solution. |
Handling information describes laboratory practice for a research reagent. It is not a preparation guide for use in humans.
the receipts
8 citedDermatology · 2014 · peer-reviewed
Australasian Journal of Dermatology · 2012 · peer-reviewed
Sexual Medicine · 2021 · peer-reviewed
Journal of the American Academy of Dermatology · 2013 · peer-reviewed
International Journal of Dermatology · 2017 · review
DermNet NZ · 2023 · review
Dr Noc (Morgan McSweeney PhD) · 2026 · investigation
U.S. Food and Drug Administration · 2026 · regulatory
others in Cosmetic