Melanotan II

What is Melanotan II?

Melanotan II, often shortened to MT-2, is a synthetic peptide based on alpha-melanocyte-stimulating hormone, the body's natural signal for skin pigment. It was made at the University of Arizona in the late 1980s and early 1990s, in the same program that produced melanotan I. The goal was a sunless tan that might lower skin cancer risk.

Early volunteers noticed something else. Along with tanning, the peptide caused nausea, reduced appetite and spontaneous erections. That finding led to small pilot studies in men with erectile dysfunction and, eventually, to a derivative called bremelanotide. Bremelanotide was approved by the FDA in 2019 as Vyleesi for low sexual desire in premenopausal women.

Melanotan II itself was never approved anywhere. It is sold online as a research chemical and used for tanning, appetite suppression and sexual effects. Regulators in the US, UK, Australia and elsewhere have issued public warnings about it.

How Melanotan II works

Your body has a family of melanocortin receptors. MC1R on skin pigment cells controls tanning. MC3R and MC4R in the brain help regulate appetite, energy use and sexual arousal. Natural alpha-MSH touches several of these. Melanotan II does the same, only much more strongly and for longer.

That is the core problem. You cannot take Melanotan II for a tan without also stimulating the brain receptors that cause nausea, appetite loss, flushing and erections. The effects come as a package.

Chemically, Melanotan II is a cyclic lactam heptapeptide, Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2. The ring structure and the D-phenylalanine protect it from enzymes and lock it into a shape that binds melanocortin receptors with high affinity. It is a potent, non-selective agonist at MC1R, MC3R, MC4R and MC5R. MC1R signaling through cyclic AMP raises eumelanin production in melanocytes. MC4R activation in the hypothalamus and spinal pathways reduces food intake and triggers erectile responses, and it also drives the nausea and blood pressure effects.

What the research shows on Melanotan II

Human data on Melanotan II is limited to a handful of small studies from the 1990s and early 2000s. Small early trials in healthy volunteers showed that injections darkened skin, mainly in sun-exposed areas, and confirmed the nausea, yawning and stretching, and erections seen anecdotally. Small crossover studies in men with erectile dysfunction reported erections after injection compared with placebo. These studies had dozens of participants at most and lasted days to weeks.

None of that work led to approval for Melanotan II itself, although it helped map the brain's melanocortin system that later approved drugs target. The developers moved on to bremelanotide, which keeps the sexual effects but has less tanning activity, and to more selective molecules. There are no long-term trials of Melanotan II for any use, and no trials of the doses or cycles used by people who buy it online.

Much of what is known about its harms comes from case reports. These describe new or rapidly changing moles, eruptive naevi, and melanomas diagnosed in users. Case reports cannot prove cause, but they are consistent with what the drug does to pigment cells. Other reports describe priapism, kidney problems and muscle breakdown after use, although these are rare and hard to attribute.

Studied for: Tanning, Appetite suppression, Erectile function.

Melanotan II reference data

Melanotan II dosage in published research

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How Melanotan II is used in practice

There is no legitimate medical use. Melanotan II is not prescribed by US telehealth services and is not a lawful compounding ingredient. It is bought online as freeze-dried powder, mixed with bacteriostatic water, and injected under the skin. Nasal sprays are also sold. Users commonly combine injections with sunbed sessions to speed tanning, which adds UV damage to the equation.

Product quality is a known issue. Laboratory analyses of products bought online have found impurities and peptide content that does not match the label, and sterility is never guaranteed. Tanning products sold through social media and gyms often give no clear manufacturer. Because there is no oversight, a buyer has no reliable way to know what is in the vial. Social media has driven much of the recent interest. Tanning injections and nasal sprays are promoted with before-and-after photos, often with no mention of side effects or of who made the product. Health agencies in several countries have responded with public warnings aimed at young adults and sunbed users.

Melanotan II risks and side effects

Side effects are common and appear early. They include nausea, often severe with the first doses, facial flushing, spontaneous erections, yawning, fatigue, reduced appetite and darkening of the face and moles. Some people develop new freckles or patches of uneven pigment.

The most serious concern is skin cancer. Melanotan II darkens existing moles and can make new ones appear, which makes changes harder to spot. People with a personal or family history of melanoma, or with many atypical moles, face the highest stakes. Anyone who has used it should have moles checked by a dermatologist.

Other risks include priapism, which is a medical emergency, raised blood pressure and heart rate, and possible interaction with erectile dysfunction drugs. It should not be used in pregnancy or by people with heart disease. Injecting unregulated powders carries a risk of infection and abscesses. Long-term safety is simply unknown.

Reported side effects

Alternatives to Melanotan II

For a tan, sunless tanning lotions and sprays with dihydroxyacetone give color without injections or UV exposure. Sun protection is still needed.

For sexual function, approved options have real evidence. PDE5 inhibitors such as sildenafil and tadalafil treat erectile dysfunction. Bremelanotide (Vyleesi) and flibanserin (Addyi) are approved for low sexual desire in premenopausal women. For appetite and weight, GLP-1 based drugs such as semaglutide and tirzepatide are far better studied, and setmelanotide (Imcivree) is an approved MC4R agonist for specific genetic forms of obesity.

Questions for a clinician

• What evidence applies to my situation, and at what level?
• What established alternatives should I consider first?
• What monitoring would be necessary, and how often?
• Can this be prescribed at all where I live, or only sold for research?