Melanotan II: The Skin-Cancer Drug That Became a Black-Market Tan
Melanotan II was developed at the University of Arizona in the 1990s as a candidate for preventing UV-driven skin cancer by stimulating melanin production without sun exposure. Its first human trial (3 volunteers) confirmed that, but also turned up an unplanned finding: spontaneous erections. A follow-up 20-person trial chased that effect instead, and it's what led, through a separately developed and more selective analog, to bremelanotide (Vyleesi), the only FDA-approved drug in this lineage. Melanotan II itself was never pursued to approval. It's sold today exactly as an unregulated injectable or nasal tanning product, the same use one seller was later criminally convicted over.
Reviewed by the PepGuard team · Last reviewed Jul 28, 2026
Synthetic lactam-bridged cyclic heptapeptide analog of alpha-MSH: Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2 · also sold as MT-2, MT-II, Melanotan 2
Photo: National Cancer Institute / UnsplashIt wasn’t designed to be a tanning drug.
Researchers at the University of Arizona built Melanotan II in the 1990s chasing a real medical goal: a way to stimulate melanin production, and therefore UV protection, without sun exposure, as a skin-cancer prevention strategy. Its first human test, a 3-person pilot trial, confirmed the tanning effect. It also turned up something nobody was looking for: spontaneous erections, alongside a distinctive stretching-and-yawning reflex, in the same volunteers.
That side effect became the story. A follow-up 20-person trial tested Melanotan II specifically for erectile dysfunction and found it worked without sexual stimulation in 17 of 20 men. From there, researchers didn’t keep developing Melanotan II itself, they developed a separate, more selective analog around the erection-inducing effect. That analog, bremelanotide, was approved by the FDA in 2019 as Vyleesi, for hypoactive sexual desire disorder in women (see PepGuard’s PT-141 report for that drug’s own dosage and evidence). Melanotan II, the compound that started all of it, was never pursued to approval for anything. Today it’s sold exactly as an unregulated tanning product, off-label and outside any clinical protocol.
What the two real trials actually used.
| What's cited | Range |
|---|---|
| Pilot dose-escalation trial (Dorr et al. 1996, n=3, subcutaneous, tanning endpoint) | 0.01 mg/kg starting dose, escalated by 0.005 mg/kg increments to 0.025-0.03 mg/kg, daily (Mon-Fri) for 2 weeks |
| Erectile-response trial dose (Wessells et al. 2000, n=20, subcutaneous) | 0.025 mg/kg, single dose per test session |
| Dose linked to a rhabdomyolysis case report (Nelson et al. 2012, single patient) | 6 mg subcutaneous, self-reported by the patient as six times his usual dose |
Two real trial doses exist, and they answer different questions. The 1996 pilot study (n=3) escalated from 0.01 mg/kg to 0.025-0.03 mg/kg subcutaneously, dosed daily (Monday-Friday) for 2 weeks, to test tanning. The 2000 study (n=20) used a flat 0.025 mg/kg subcutaneous dose to test erectile response. Neither trial tested, or endorses, a cosmetic tanning "loading and maintenance" schedule; every such protocol circulating online is a vendor/community convention with no clinical study behind it, and we're not repeating specific figures for it here because none trace back to a primary source we could verify. The one other real data point on dose comes from a toxicology case report: the treating physicians described a patient's overdose of 6 mg subcutaneous as six times his usual starting dose, which implies roughly a 1 mg community convention, but that figure comes from the patient's self-report, not a trial.
What’s been reported when people use more than the trials tested.
Neither published trial evaluated safety at the doses or duration people actually use for cosmetic tanning. What exists instead is a small number of formally documented case reports.
| Signal | Frequency | Context |
|---|---|---|
| Skin pigmentation (facial, upper-body, buttock) | commonly reported | The intended tanning effect. Confirmed in 2 of 3 subjects in the 1996 pilot trial by reflectance measurement and visual assessment. |
| Spontaneous penile erections | commonly reported | The unplanned finding that redirected this compound's development. Reported in both the 1996 pilot trial and the 2000 erectile-response trial (17 of 20 subjects, without sexual stimulation). |
| Nausea | commonly reported | Reported at most dose levels in the 1996 pilot trial; the 2000 trial reported severe nausea in 12.9% of dosing sessions. |
| Rhabdomyolysis and systemic toxicity at supratherapeutic doses | rarely reported | A published case report describes a patient who injected roughly 6x his usual dose and required 3 days of ICU care for rhabdomyolysis and acute kidney involvement. |
| New or changing moles, melanoma | rarely reported | A published case report documents melanoma diagnosed after 3-4 weeks of unsupervised Melanotan II use. This kind of case report doesn't establish how often it happens, only that it has happened and been formally documented. |
| Effects of nasal-spray administration | unknown / not studied | Both primary human trials used subcutaneous injection. The nasal-spray version some vendors sell has not been tested in either published trial. |
One seller of this exact product was criminally convicted.
Melanotan II has never been approved by the FDA for any use, and unlike most peptides on this site, it was never nominated for the FDA's 503A compounding-bulks list, its distribution isn't running through that pathway at all. Instead, FDA has treated it as a straightforwardly illegal unapproved drug sold direct to consumers. Per FDA's own debarment order (Docket No. FDA-2015-N-4169), the agency sent a warning letter to Melanocorp, Inc. on or about August 30, 2007, stating that Melanotan II "constituted a new drug under the FDCA that could not be introduced or delivered for introduction into interstate commerce without an FDA approved application," after the company marketed it as an injectable tanning product with claims it could reduce skin cancer rates and cure rosacea. Melanocorp told the FDA it had stopped US sales, then continued shipping the product domestically through at least April 2009. FDA's finding was that this conduct amounted to a federal felony under 18 U.S.C. 371, and under Section 306(c)(2)(A)(ii) of the FDCA, the individual behind Melanocorp was permanently debarred from providing services to any company with an FDA drug application. That's a materially different regulatory story than a withdrawn compounding nomination: it's an actual criminal enforcement case naming this specific product.
Every claim above, traced back.
Two published human trials, two published case reports, and the FDA’s own debarment order naming this product. Click through and check them yourself.
Melanotan II questions, answered.
No, and it was never even nominated for the FDA's compounding-bulks pathway most other unapproved peptides go through. FDA has instead treated it as a straightforwardly illegal unapproved drug: in 2007 it sent a warning letter to a seller, Melanocorp, and when the company kept shipping it anyway, that led to a felony conviction and a permanent FDA debarment order in 2016. That's a criminal enforcement case, not a withdrawn nomination.
They share an origin. The same University of Arizona research group that ran Melanotan II's human trials found it caused spontaneous erections as a side effect of testing it for tanning. That finding is what eventually led to bremelanotide (marketed as PT-141, then approved by the FDA in 2019 as Vyleesi), a separately developed, more selective analog. Melanotan II itself was never pursued to approval and is only sold today as an unregulated tanning product.
The only doses with real trial data behind them are 0.01-0.03 mg/kg (escalating, for tanning) and a flat 0.025 mg/kg (for the erectile-response trial), both subcutaneous. The "loading dose then maintenance" schedules that circulate in tanning communities aren't drawn from either trial or any other published study we could verify, so we're not repeating specific numbers for them here.
There's no trial that evaluated its safety for cosmetic tanning use at the doses people actually use it at. What exists instead are two published case reports: one patient who overdosed and needed 3 days of ICU care for rhabdomyolysis, and one patient diagnosed with melanoma after several weeks of use. Case reports don't tell you how often something happens, only that it has happened and been documented in the medical literature.
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