Melanotan II: It Tans, But It's Unapproved and Carries Real Harms

Melanotan II is a man-made peptide sold online to darken skin (people call it “the tan jab”), curb appetite, and boost sex drive. No country has approved it as a drug, and the way people actually use it has never been put through a proper, controlled study.

What it is

Melanotan II is a lab-made copy of a natural hormone called alpha-melanocyte-stimulating hormone (alpha-MSH for short). It switches on a whole family of cell “switches” known as melanocortin receptors (MC1R through MC5R), and it isn’t very picky about which ones it flips. Turning on MC1R tells skin cells to make more melanin, the pigment that produces a tan. Turning on MC4R in the brain affects appetite and sexual arousal. Because it hits so many switches at once, it produces a wide range of effects, and a messy list of side effects to match.

People usually inject it just under the skin (subcutaneous, meaning into the layer right beneath the surface); some sellers offer it as a nasal spray. It is not the same thing as Melanotan I (also called afamelanotide, brand name Scenesse, which is an FDA-approved drug for a rare condition that makes people extremely sensitive to light), and it is not the same as bremelanotide.

The claims

Sellers and users say it gives you a deep tan with little sun, protects you from sunburn, kills your appetite so you lose weight, and increases erections and desire.

What the evidence actually shows

The human research is old, small, and narrow. In the 1990s and 2000s, a University of Arizona group ran small placebo-controlled crossover trials (studies where each person is compared against a dummy treatment) in men with erectile dysfunction. In one, 8 of 10 men got erections after an injection of Melanotan II compared with placebo; later studies in roughly 20 men reported more erections and, by the men’s own accounts, more desire. These were short studies that looked only at sexual response, not at safety or at whether it tans skin over time.

Here is the key gap: there are no controlled human trials showing that Melanotan II works or is safe for the thing most people buy it for, tanning, and none for weight loss either. So the research that does exist doesn’t actually cover its main real-world uses. A cousin drug in the same family, bremelanotide (sold as Vyleesi), did go through full trials and is FDA-approved for one specific condition, low sexual desire in premenopausal women that isn’t caused by something else. But that is a separate, regulated drug, and it tells us nothing about whether unregulated Melanotan II is safe.

So why grade it “Preliminary” (grade 6) at all? Because, in a narrow way, the erectile-response research is real: small, short, placebo-controlled testing in people, which counts as genuine early human evidence for that one outcome. The honest catch is that this evidence doesn’t stretch to cover tanning, weight loss, or long-term safety, and those are exactly what people are buying it for.

Legal and regulatory status

Melanotan II is not approved by the FDA for any use. The FDA treats products sold for people to use as unapproved new drugs and mislabeled cosmetics, and it has sent warning letters to sellers. The UK’s MHRA (the British medicines regulator) and Australia’s Therapeutic Goods Administration have both warned the public against it and treat selling it as illegal, yet it is still widely sold on the gray market. For athletes: Melanotan II isn’t listed by name on the WADA Prohibited List, but since it has no approval for medical use anywhere, it most likely falls under the S0 “non-approved substances” catch-all, which is banned at all times. Competitors should treat it as banned and check the current list. As of 2026 there is no legal, regulated source of it for human use.

Safety

This is the real problem. Harms recorded in case reports (write-ups of individual patients) and in regulator warnings include: priapism (a painful erection that won’t go down and can cause permanent damage), nausea and vomiting, flushing, changes in blood pressure, and rhabdomyolysis (severe breakdown of muscle tissue) along with kidney injury, reported after a large overdose.

The most worrying part: Melanotan II revs up melanocytes, the cells that make pigment, and it can’t tell normal skin apart from existing moles. Case reports describe moles getting darker and changing fast, new odd-looking moles appearing, and melanomas (a dangerous skin cancer) being diagnosed during or soon after use. These reports show a link, not proof that the drug caused the cancer, but they are a serious red flag. And because the drug is unregulated, the vials people buy may be contaminated, mislabeled, or wrongly dosed, and injecting, or sharing needles, adds the risk of infection.

Bottom line

Melanotan II clearly does something, it tans skin and can trigger erections, but “it works” is not the same as “it’s safe or smart.” Its real-world uses have never been tested in controlled human studies, it’s unapproved and often illegal, and it carries documented risks including reports of melanoma. The honest read: the evidence backing how people actually use it is thin, while the safety warnings against it are not.

Evidence grade: 6/10 · Preliminary.

Sources

• Wessells H, et al. Synthetic melanotropic peptide initiates erections in men with psychogenic erectile dysfunction: double-blind, placebo controlled crossover study. J Urol. 1998. PMID 9679884
• Wessells H, et al. Melanocortin receptor agonists, penile erection, and sexual motivation: human studies with Melanotan II. Int J Impot Res. 2000. PMID 11035391
• Wessells H, et al. Effect of an alpha-melanocyte stimulating hormone analog on penile erection and sexual desire in men with organic erectile dysfunction. Urology. 2000. PMID 11018622
• DermNet NZ — Melanotan II
• Therapeutic Goods Administration (Australia) — Don’t risk using tanning products containing melanotan
• Nelson ME, Bryant SM, Aks SE. Melanotan II injection resulting in systemic toxicity and rhabdomyolysis. Clin Toxicol. 2012. PMID 23121206
• Cancer Research UK — Tanning, fake tan and Melanotan (UK/MHRA warnings)
• FDA — Vyleesi (bremelanotide) approval letter, NDA 210557, June 2019
• Cousen P, et al. Melanoma associated with the use of Melanotan-II (Clinical and Experimental Dermatology, 2009)