Melanotan II: approved nowhere, and why regulators keep naming the melanotan peptide

The short answer

• “Melanotan” names two molecules. Melanotan I is afamelanotide, marketed as SCENESSE, an approved 16 mg subcutaneous implant for erythropoietic protoporphyria. Melanotan II has never been approved anywhere for anything.
• Evidence tier for melanotan II: Early human data at its most generous, and Preclinical only for most of what it is used for. Its entire human efficacy literature is three small studies from 1996 to 2000, the largest with 10 subjects.
• Development was abandoned, not merely never pursued: the molecule went into humans, produced effects, and was set aside in favour of its own metabolite, bremelanotide.
• Everything published since is essentially a harms literature: melanoma including oral mucosal melanoma, eruptive and atypical naevi, ischemic priapism, rhabdomyolysis with sympathomimetic toxicity, renal infarction, and posterior reversible encephalopathy syndrome.
• As of September 2026 melanotan II is in no FDA 503A compounding category, and Health Canada has named melanotan I and II in advisories in April 2025, August 2025 and 9 April 2026.

Two molecules, one nickname

Afamelanotide is a linear 13 amino acid peptide, the same length as native alpha-melanocyte-stimulating hormone, with two substitutions for stability and potency. It is relatively selective for MC1R, the melanocortin receptor on melanocytes, and it is supplied as a bioresorbable implant rod placed by a trained clinician.

Melanotan II is a cyclic heptapeptide, and it is nonselective across MC1R, MC3R, MC4R and MC5R. The cyclization gives it potency; the nonselectivity gives it the sexual and cardiovascular effects that the tanning market treats as a bonus and that pharmacology treats as the problem. MC1R activation increases eumelanin synthesis, which darkens skin. MC3R and MC4R in the central nervous system handle sexual arousal, appetite suppression and cardiovascular effects, including the blood pressure rise and heart rate fall seen with this class. Afamelanotide mostly hits the first. Melanotan II hits all of them.

A third molecule in this family explains the whole story. Bremelanotide, also called PT-141, is the metabolite of melanotan II in which the amide at one end is hydrolysed to a free acid. They differ only at that position. Bremelanotide kept the sexual-response activity and went on to FDA approval as Vyleesi. Melanotan II did not. Our side by side comparison walks through what separates them.

What the three human studies actually found

Dorr and colleagues published a pilot phase 1 study in 1996 in three healthy men, with escalating subcutaneous doses. Two of the three developed increased facial, upper body and buttock pigmentation, mild nausea occurred at most dose levels, and one of two subjects had significant somnolence and fatigue at the higher dose. Subjects also had spontaneous erections lasting one to five hours, preceded by a yawning and stretching complex, which is a direct human observation of central melanocortin activity.

Wessells and colleagues ran two crossover studies in men with erectile dysfunction, 10 subjects each. In the 1998 study, 8 of 10 men with psychogenic erectile dysfunction had clinically apparent erections, with mean duration of tip rigidity above 80% of 38.0 minutes versus 3.0 minutes on placebo. In the 2000 study, erections followed 12 of 19 melanotan II injections versus 1 of 21 placebo injections, with mean tip rigidity above 80% for 45.3 versus 1.9 minutes, and increased sexual desire reported.

That second study also reported severe nausea in 4 of 19 injections at an effective dose. That tolerability figure at a working dose is the reason the programme moved to bremelanotide instead of continuing with melanotan II.

So the effects are real. They were measured, in small numbers, twenty-five years ago, and then the file was closed.

The harms are documented cases, not hypotheticals

Each item below is a published human case or series.

Melanoma. Melanotan-associated melanoma was reported in 2011. A 2025 report described oral mucosal malignant melanoma in a melanotan II nasal spray user.

Eruptive and atypical naevi. In one published case, a man with prior melanoma developed crops of new atypical naevi under self-administered alpha-MSH, with existing naevi darkening and acquiring growth features, all regressing after he stopped. The authors concluded these peptides can drive proliferation of neoplastic melanocytic cells in predisposed patients.

Ischemic priapism. Reported both at ordinary use and in overdose, including a case requiring operative penoscrotal decompression after aspiration and phenylephrine failed.

Rhabdomyolysis with sympathomimetic toxicity. A man who injected 6 mg, six times his own understood starting dose, developed a heart rate of 146 bpm, dilated pupils, sweating and tremor, with creatinine 2.25 mg/dL, CPK 1,760 IU/L and troponin 0.23 ng/mL.

The pigment effect is not merely cosmetic: darkening naevi makes melanoma surveillance harder to read at the same time as the drug may be promoting melanocytic proliferation. Tanning use also combines the drug with ultraviolet exposure, while the population most motivated to tan, fair-skinned people with many naevi or a family history of melanoma, is exactly the population at highest risk.

The nasal route deserves a separate line. It has never been studied for safety in humans, it is heavily marketed, and the mucosal melanoma case report concerned a nasal spray user.

The approved molecule is not the same product

It is worth being precise about afamelanotide, because “melanotan I” vials are sold as if they were the same thing. The approved product is a single 16 mg implant placed subcutaneously by a clinician trained by the manufacturer, every two months, with 30 minutes of observation afterwards; it is bioresorbable and may be impossible to locate or remove from about ten days after insertion. Its indication is prevention of phototoxicity in adults with erythropoietic protoporphyria, a rare light-sensitivity disease, not cosmetic tanning, and the labelled effect size is real and modest: in one pivotal study, median hours in direct sunlight on pain-free days over 180 days was 64.1 with afamelanotide versus 40.5 with vehicle.

The label also requires full-body skin examination twice yearly, because generalized increased pigmentation and darkening of pre-existing naevi and freckles are expected pharmacologic effects. That is the single most important monitoring instruction in the document, and in principle it applies to anyone exposed to any MSH analogue by any route. A self-injected bolus of unregulated powder sold as “melanotan I” is not this product.

Where regulators stand as of September 2026

In the United States, melanotan II is not approved for anything. It sat in FDA’s 503A Category 2, the list of bulk substances presenting significant safety risks, until the nominators withdrew their nominations; the categories list updated 14 May 2026 no longer shows it there, and it has never been in Category 1.

That change is procedural, not a safety clearance. Eligibility for lawful 503A compounding requires a USP or NF monograph, being a component of an approved drug product, or appearing on the bulks list, and melanotan II has none of those. FDA has said it intends to consult its Pharmacy Compounding Advisory Committee about melanotan II before the end of February 2027, and its original Category 2 basis included case reports of melanoma, posterior reversible encephalopathy syndrome and priapism.

In Canada, afamelanotide is authorized as SCENESSE, DIN 02569825, with a history date of 9 July 2026. Melanotan I and II are not authorized. Both were named among unauthorized injectable peptides in Health Canada’s April 2025 clinic seizure advisory and its 1 August 2025 Canada Peptide advisory, and both appear in the 9 April 2026 public advisory, which states plainly that a “for research use only” label does not make a product legal or safe for human use, that injectable peptides are generally regulated as prescription drugs in Canada, and that buyers should check for a DIN.

On anti-doping, neither molecule is named on WADA’s 2026 Prohibited List. Because melanotan II has no approval for human therapeutic use by any government health authority, section S0, non-approved substances, comes into play for tested athletes. Afamelanotide is approved, so S0 does not apply to it.

If someone has used it

The clinically useful actions after disclosure are narrow: stop, get a full-body skin examination with dermoscopy and documented follow-up of any changing lesion, and record the exposure permanently, because prior MSH analogue exposure changes how a changing naevus should be read. Priapism, chest symptoms, dark urine or muscle pain, flank pain and neurological symptoms including visual disturbance or seizures each correspond to a documented serious harm. An erection lasting beyond four hours after any melanocortin agonist is a urological emergency.

The bottom line

Melanotan II produced measurable pigmentation and erectile effects in three small studies, then its development was abandoned in favour of a metabolite with better tolerability. Twenty-five years later there is still no dose-ranging safety study, no repeated-dosing study, no human pharmacokinetic data, and nothing at all on the nasal route that is most heavily sold. What exists instead is a case series of melanoma, priapism, rhabdomyolysis, renal infarction and encephalopathy. The safety case against injected or inhaled MSH analogues for cosmetic purposes is about as strong as it gets in this field without a randomised trial. See the molecule page for the full record.

Education only. This page is educational. Most compounds referenced are not approved for human use, and a “research use only” label carries no legal status of its own. Nothing here constitutes medical advice, diagnosis, or treatment.

Sources

• Dorr RT, et al. Evaluation of melanotan-II, a superpotent cyclic melanotropic peptide in a pilot phase-I clinical study. Life Sci, 1996.
• Wessells H, et al. Synthetic melanotropic peptide initiates erections in men with psychogenic erectile dysfunction: double-blind, placebo controlled crossover study. J Urol, 1998.
• 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.
• Cardones AR, Grichnik JM. alpha-Melanocyte-stimulating hormone-induced eruptive nevi. Arch Dermatol, 2009.
• Yassin Alsabbagh A, et al. Melanotan II nasal spray: a possible risk factor for oral mucosal malignant melanoma? Int J Oral Maxillofac Surg, 2025.
• Nelson ME, et al. Melanotan II injection resulting in systemic toxicity and rhabdomyolysis. Clin Toxicol (Phila), 2012.
• Mallory CW, et al. Melanotan Tanning Injection: A Rare Cause of Priapism. Sex Med, 2021.
• Langendonk JG, et al. Afamelanotide for Erythropoietic Protoporphyria. N Engl J Med, 2015.
• FDA. SCENESSE (afamelanotide) prescribing information; Bulk Drug Substances Nominated for Use in Compounding Under Section 503A, updated 14 May 2026. Health Canada public advisories, April 2025, 1 August 2025 and 9 April 2026; Drug Product Database record for SCENESSE, DIN 02569825. WADA 2026 Prohibited List, effective 1 January 2026, section S0.