Melanotan 2

What it is

The story begins at the University of Arizona, in the middle of the desert. In the eighties, Victor Hruby and Mac Hadley were looking for a way to prevent skin cancer: tan the skin before the sun hits it. Natural tanning is the body’s own light protection; the pigment melanin lies over the cell nuclei like an umbrella.

Tanning is controlled by the hormone alpha-MSH, which is released after UV exposure and tells the pigment cells to produce melanin. The natural hormone is very short-lived. The researchers therefore built more stable variants: first melanotan 1, an elongated linear form, then melanotan 2, a small, ring-shaped peptide of seven building blocks, more robust and considerably more potent. The small ring has a side effect: melanotan 2 reaches the brain better than its big brother.

Two drugs as descendants

The basic idea from Arizona made it to approval, just not with melanotan 2. Afamelanotide, brand name Scenesse, was developed from the older melanotan 1, not from melanotan 2. The European Commission approved it in December 2014, as an implant for people with erythropoietic protoporphyria, a rare disease in which light triggers severe pain.

The second descendant arose from an observation that belongs to peptide folklore: in the early phase, a researcher is said to have had an erection lasting hours after accidentally taking a double amount. This is documented only as an anecdote, but the studies confirmed the central effect on sexuality. Bremelanotide, known as PT-141, was developed from melanotan 2 itself and has been approved in the US since 2019 as Vyleesi for reduced sexual desire in women before menopause. And setmelanotide, an approved drug for rare genetic forms of obesity, also works via the same MC4R receptor.

How it works

Melanotan 2 is not very selective and activates several of the five melanocortin receptors. Via MC1R on the pigment cells it stimulates the formation of eumelanin, the brown-black protective pigment. The skin tans, even with considerably less UV light than usual.

MC4R sits mainly in the hypothalamus and controls appetite and sexual arousal. That is why melanotan 2 does not work like classic erectile dysfunction drugs via the blood vessels, but via arousal circuits in the brain. One molecule, three effects. It is precisely this spread that made approval as a tanning agent difficult: an agent that simultaneously tans, suppresses appetite and triggers erections can hardly be positioned as a cosmetic.

What users report

In bodybuilding and beach circles, melanotan 2 has been around since the 2000s, often under the nickname Barbie drug: tanned, slim, more desire. Users describe a deep, even tan with little sun that lasts for weeks and fades over weeks to months after stopping. Fair skin types who otherwise only burn sometimes report a real tan for the first time. On top of that come dampened hunger in the first weeks and increased libido.

In the scene, melanotan 2 is often combined with sun or a tanning bed to start the tan. Exactly this combination reappears in several melanoma case reports. A peptide tan is not a free pass for UV, and it does not replace sun protection.

What the studies show

Dorr 1996 — the first human study

Single-blind phase 1 pilot study with 3 healthy men, melanotan 2 or saline under the skin on alternating days over two weeks. Two participants showed more pigment one week after the end of dosing, measured by reflectance and visible. In addition, spontaneous erections occurred 1 to 5 hours after dosing, as well as mild nausea and fatigue. A very small study, but the first evidence in humans.

Wessells 1998 — psychogenic erectile dysfunction

Double-blind, placebo-controlled crossover study with 10 men without an organic cause, erections measured by RigiScan over 6 hours. Clinically visible erections occurred in 8 of 10 men. The duration with more than 80 percent rigidity averaged 38.0 minutes versus 3.0 on placebo. Nausea, yawning and reduced appetite were more frequent but did not require treatment.

Wessells 2000 — organic cause and desire

In a second study with 10 men with organic risk factors, 12 of 19 injections triggered erections, versus 1 of 21 on placebo. Sexual desire increased. Pooled across 20 men, 17 developed an erection; increased desire occurred after 68 percent of doses versus 19 percent on placebo. The downside: 4 of 19 injections were accompanied by severe nausea.

Where the data stop

All controlled human data come from the nineties and around 2000, from a single research group, with 3 to 20 participants each and over days to a few weeks. There is no controlled study that systematically measures tanning with melanotan 2, follows it over months or compares it with sun protection. The appetite effect is noted in studies only as a secondary finding, not tested as an endpoint.

The central safety question is also open. Whether melanotan 2 causes melanomas is unresolved: the case reports show a temporal association, often together with tanning beds, but no proof. A review of MC1R activation notes that more pigment could lower melanoma risk but does not prevent melanoma, especially in the presence of risk factors. The original idea of skin cancer prevention has never been tested for melanotan 2.

Status, approval and legal

Melanotan 2 is not approved as a medicine in Germany, the EU or the US. In 2010 the BfArM strongly advised against obtaining melanotan-containing products from internet sources and using them cosmetically: quality, safety and efficacy had not been sufficiently studied; the risks named concern the cardiovascular system, the digestive tract and unintended changes in skin coloration. The British medicines regulator MHRA additionally warned of contamination and of infections from shared needles. It is sold as a research peptide; purity and content are a matter of trust. In sport, as a substance not approved anywhere, it falls under class S0 of the WADA prohibited list.

Safety

The common side effects are known from the studies: nausea, facial flushing, yawning and stretching, fatigue, reduced appetite, and in men spontaneous erections. Rare, but an emergency, is priapism, a painful prolonged erection, on which several case reports exist. The main dermatological problem is moles: darkening and newly appearing nevi have been published, sometimes as early as 24 hours after a single injection, as well as atypical nevi and several melanomas in users. Because a changing mole is the most important warning sign of melanoma, this makes early detection more difficult. Anyone with many or conspicuous moles, or with skin cancer in the family or their own history, should not be among the users. Anyone who uses it nonetheless should have their skin examined by a dermatologist beforehand and regularly. Pigmentation of the oral mucosa and ulcers at injection sites have also been described.

Sources

• Dorr et al., Life Sci 1996 (first human study)
• Wessells et al., J Urol 1998 (psychogenic erectile dysfunction)
• Wessells et al., Urology 2000 (organic erectile dysfunction)
• Wessells et al., Int J Impot Res 2000 (summary, 20 men)
• Langan et al., Br J Dermatol 2010 (review of melanotan)
• Hjuler and Lorentzen, Dermatology 2014 (melanoma case report)
• Böhm et al., J Eur Acad Dermatol Venereol 2025 (MC1R activation, benefits and risks)
• Mallory et al., Sex Med 2021 (priapism case report)
• BfArM, press release 14/10 of October 28, 2010
• EMA, Scenesse (afamelanotide), EPAR
• Minder et al., Clin Pharmacokinet 2017 (afamelanotide, synthesized in 1980 as the first alpha-MSH analogue)