01 What is Melanotan II?
In plain English.
Melanotan II is a lab-made peptide designed to copy the body's own pigment-signalling hormone, α-MSH (alpha-melanocyte-stimulating hormone). It tells pigment cells in the skin to make more melanin, which is why people inject it: to darken skin without sun exposure. It is sold online, often through gyms and beauty salons, as a "tanning peptide", and is not approved as a medicine anywhere in the world.
Crucial distinction: Melanotan II is not the same molecule as Melanotan I. Melanotan I, also called afamelanotide, brand name Scenesse, is a different peptide, and it is an approved drug. It is given as a subcutaneous implant under specialist supervision for erythropoietic protoporphyria (EPP), a rare and painful sun-sensitivity disorder. Melanotan II is the unrelated, unapproved cousin sold online for cosmetic tanning. The page you are reading is about Melanotan II. The two are often confused, sometimes deliberately by vendors.
02 How it works
The simple version, then the science.
MT-II binds to a family of receptors called the melanocortin receptors (MC1–MC5). Hitting MC1 on skin cells is what triggers melanin production and the tanning effect. But MT-II is non-selective, it also activates MC3 and MC4 in the brain and elsewhere, which is why users commonly report nausea, facial flushing, blood-pressure changes, yawning and spontaneous erections. The erectile side-effect is so consistent that a more MC4-selective version of the same chemistry, PT-141 (bremelanotide), was later developed and approved specifically for sexual dysfunction.
Go deeper · the proposed mechanism
MT-II is a cyclic heptapeptide analogue of α-MSH with a longer half-life than the native hormone. It acts as a non-selective agonist at MC1R (melanogenesis), MC3R/MC4R (CNS effects on appetite, sexual behaviour and autonomic tone) and MC5R. The same MC1R-driven melanocyte stimulation that produces tanning is the biologically plausible mechanism for the eruptive-nevi and mole-darkening signals seen in dermatology case reports, paracrine α-MSH signalling normally regulates melanocyte activity, but MT-II pushes that pathway systemically and pharmacologically.
03 What it's used for
Each use graded by how strong the evidence actually is.
- AnecdotalSkin tanningThe desired effect, and the one that drives sales. MT-II does measurably stimulate melanin production. But there are no controlled human trials of MT-II for cosmetic tanning, and the safety trade-off (see below) is the entire issue. This use is not approved by any medicines regulator.
- AnecdotalErectile responseWell-documented as a side effect, and the reason MT-II was historically of interest in sexual-medicine research. The refined, MC4-selective version, PT-141 (bremelanotide), has since superseded MT-II for this use.
- PreclinicalAppetite suppressionMC4 agonism reduces food intake in animal models. Of historical research interest only; never pursued as a clinical product, and not a reason anyone uses MT-II today.
04 What the evidence says
The pharmacology is real: MT-II does drive melanin production through MC1R. What MT-II does not have is any controlled human trial showing that tanning is safe over the medium term, or any clinical evidence base to support its use. The published human literature on MT-II is, almost entirely, dermatology and toxicology case reports describing what went wrong: eruptive new moles (Cousen et al. 2009), α-MSH-induced eruptive nevi (Cardones & Grichnik 2009), dysplastic nevi (Reid et al. 2012), at least one published melanoma in situ (Paurobally et al. 2012), and systemic toxicity including rhabdomyolysis (Nelson et al. 2012) and renal infarction. Causation in any single case cannot be proven. But a non-zero number of melanoma case reports in young users of a peptide that systemically activates melanocytes is exactly the safety signal you would expect to see if the mechanism were biologically plausible, and that is what is being seen.
05 Dosing & administration
Reported in the literature, information not advice.
No safe or effective dose has been established. The development programme was abandoned and no regulator has approved MT-II for any indication. Online communities describe milligram-range subcutaneous "loading" then "maintenance" injections, but these regimens are not medical protocols. The Nelson et al. 2012 rhabdomyolysis case involved a single 6 mg subcutaneous dose, many times the amount often quoted online as a starting point, which on its own should give pause about the precision of any "protocol" circulating on forums. A qualified clinician should be consulted before considering any peptide; for MT-II specifically, that conversation should also include the case-report literature below.
06 Side effects & safety
Melanotan II has the most concerning published safety profile of any peptide on this site. Four signals matter. First, mole and melanoma risk. Multiple peer-reviewed case reports describe new moles erupting, existing moles rapidly darkening or changing shape, and dysplastic nevi developing in MT-II users (Cardones & Grichnik 2009; Cousen et al. 2009; Reid et al. 2012), and at least one published case of melanoma in situ has been associated with MT-II use (Paurobally et al. 2012). Causation in any individual case is not provable, but the mechanism, driving melanocyte activity, is biologically plausible, and the pattern is consistent enough that public-health bodies have warned consumers. Second, systemic toxicity. A 39-year-old man in the Nelson et al. 2012 case presented with sympathomimetic toxicity, tachycardia, hypertension and rhabdomyolysis after a single MT-II injection. A separate case series documents renal infarction associated with MT-II use. Third, common acute effects include nausea, facial flushing, GI upset, blood-pressure changes, yawning and spontaneous erections. Fourth, quality control on the illegal market is absent, vials sold online are unregulated, and purity, identity and sterility are not guaranteed. If you have any moles you are watching, a family history of melanoma, Fitzpatrick I–II skin, or are immunosuppressed, MT-II is a particularly poor choice. Any new or changing mole during or after MT-II use is grounds for immediate dermatology review.
07 Where to buy (research use only)
Vetted on quality and transparency, not an endorsement to use.
08 Legal & regulatory status
- UKConsidered by the MHRA to be an unlicensed medicinal product. Sale or supply for human use is illegal. The MHRA has run multiple enforcement actions against websites supplying UK customers; Cancer Research UK advises consumers not to use it.
- USNot FDA-approved. Not on the list of bulk substances permitted for compounding. Sold only as a "research chemical", not for human consumption.
- EUNo marketing authorisation in any EU member state. National regulators across the EU/EEA have issued consumer warnings.
- AUS / NZProhibited for sale for human use. Australian and New Zealand regulators have issued consumer-safety alerts about online MT-II products.
- Sport (WADA)Not currently listed on the WADA Prohibited List, but the safety profile makes the sport question largely moot. We note it honestly rather than imply a clean status.
09 Clinical studies & research
Primary sources. Read the science yourself.