Melanotan II and tanning nasal sprays: what the evidence shows

The short answer

Tanning nasal sprays contain melanotan II, an unlicensed synthetic peptide that is not the same molecule as the melanocortin drug approved for a skin condition. Its human tanning evidence is a 1996 pilot study in three men, and what the literature added afterwards is case reports of harm.

A peptide is a short chain of amino acids, the same building blocks your body uses to make proteins. The peptide inside a tanning nasal spray is almost always melanotan II, a synthetic copy of part of a hormone your own body makes called alpha-melanocyte-stimulating hormone, or α-MSH, which tells pigment cells in your skin to make more pigment [2].

Three facts do most of the work on this page. Melanotan II is unlicensed, and its sale is illegal in the United Kingdom and in many other countries around the world [11]. The α-MSH analogue that did clear regulatory review is a different molecule called afamelanotide, approved in the United States since 2019 and for a rare light-sensitivity disorder rather than for tanning [4]. And when researchers bought melanotan II vials from three online shops and measured what was in them, the vials contained between 4.32 and 8.84 mg of the peptide even though every shop claimed each vial held 10 mg [6].

None of that is a moral argument about tanning. It is a description of a product category where the molecule is real, the pharmacology is real, and almost nothing else about it has been established. The rest of this article separates the parts that have been tested from the parts that have not, because in this particular case those two piles are shelved under the same name.

Melanotan I and melanotan II are two different molecules

Afamelanotide, often called melanotan I, is a 13-amino-acid peptide that binds predominantly to the MC1 receptor and has been an approved prescription drug in the United States since 2019. Melanotan II is a smaller ring-shaped peptide that acts across melanocortin receptors without selecting between them.

Pigment cells respond to α-MSH through a receptor called MC1-R, the melanocortin 1 receptor. But melanocortin receptors are a family, and the other members of that family sit elsewhere in the body doing other jobs. Which receptors a molecule reaches is therefore not a technical footnote. It is the difference between a drug and a problem.

Afamelanotide, the molecule sold online as melanotan I, is a synthetic tridecapeptide (a peptide 13 amino acids long) and a structural analogue of α-MSH, and it binds predominantly to MC1-R [4]. It has been approved in the United States since 2019, under the brand name SCENESSE, to increase pain-free light exposure in adults with a history of phototoxic reactions from erythropoietic protoporphyria, a rare inherited condition in which sunlight causes severe skin pain [4]. That is its entire approved indication: cosmetic tanning is not on the label [4]. The review of this literature draws the line the same way, describing afamelanotide as thoroughly tested and deemed safe while the melanotans sold online are likely risky [1].

Melanotan II is a different shape entirely. It is a cyclic heptapeptide, seven amino acids closed into a ring by a lactam bridge, first described as having superpotent pigment-stimulating activity in laboratory tests [2]. And it is characterised in the clinical literature as a non-selective melanocortin-receptor agonist [8], meaning it activates the family rather than picking out the pigment receptor. That is why the reported effects of melanotan II are never confined to skin, and it is the single most useful thing to know before reading anything else about it.

There is a third molecule in the same family worth naming, because it shows what the tested version of this pharmacology looks like. Bremelanotide is described as a variation of melanotan II developed specifically for sexual stimulation [7], and it went through two identical phase 3 randomised, double-blind, placebo-controlled trials of a 1.75 mg subcutaneous dose taken as needed over 24 weeks [5]. Same family, same starting point, completely different evidentiary path.

The human tanning study behind melanotan II had three volunteers

A 1996 pilot phase 1 study gave melanotan II by subcutaneous injection to three healthy male volunteers on an alternating-day schedule and found increased pigmentation in two of them. It closed by recommending a dose for future phase 1 studies. No larger tanning trial has since replaced it.

This is the study everything rests on, and it is worth reading closely rather than by reputation. It was a single-blind, alternating-day, placebo-controlled pilot phase 1 trial in three normal male volunteers, starting at 0.01 mg/kg of melanotan II [2]. Injections were given under the skin on weekdays for two consecutive weeks, with two subjects escalated in 0.005 mg/kg increments to 0.03 mg/kg and one to 0.025 mg/kg [2]. Those numbers are study parameters and nothing else; they are printed here so you can see the scale of the trial, not so anyone can copy them.

The result was real. Two subjects had increased pigmentation in the face, upper body and buttock, measured both by quantitative reflectance and by visual perception a week after dosing ended, which the authors summarised as melanotan II having tanning activity in humans after five low doses given every other day by subcutaneous injection [2].

The side effects were real too, and they arrived at the same doses as the tan. The 0.03 mg/kg level produced Grade II somnolence and fatigue in one of the two subjects who reached it, mild nausea was reported at most dose levels, and a stretching and yawning complex appeared to correlate with the onset of spontaneous penile erections lasting one to five hours after dosing [2]. A drug that makes you sleepy, queasy and erect while it tans you is a drug hitting more than the pigment receptor, exactly as the non-selective description predicts [8].

The paper ends by recommending a single dose for future phase 1 studies [2]. That is the sentence that matters most. It is the language of a programme at its beginning. What the reviews that catalogue this literature describe two decades later is case reports of cutaneous complications from unregulated melanotan use, rather than the larger tanning trials that sentence anticipated [1], and a 2026 systematic review of tanning agents that screened 68 peer-reviewed studies still lists limited long-term safety data among its limitations [12].

A nasal spray cannot tell you the dose it delivered

Every published human dosing study of melanotan II used weight-based subcutaneous injection. The approved melanocortin drug is a controlled-release implant placed by a trained clinician, and even that produced highly variable blood levels. A spray bought online has no equivalent basis for stating what it delivers.

Look at how the tested versions of this pharmacology are administered, because the contrast is the argument. The 1996 study dosed melanotan II by subcutaneous injection in milligrams per kilogram of body weight, escalating in small increments under observation [2]. The approved MC1-R drug is not even an injection: it is a bioresorbable implant about 1.7 cm long and 1.45 mm across, containing 16 mg of afamelanotide, inserted under the skin above the hip bone every two months by a healthcare professional who has completed a training programme for the procedure [4].

That degree of control exists because dosing a peptide precisely is hard, and the label proves the point against itself. In a pharmacokinetic study of a single implant in 12 healthy adults, the label records that high variability was observed in the plasma concentrations of afamelanotide [4]. A manufactured, controlled-release, professionally placed implant still produced scattered blood levels in a formal study. A spray bottle has none of those controls.

Then there is what is in the bottle before it ever reaches a nose. The analysis of vials from three online shops found not only the shortfall against the claimed 10 mg but unknown impurities ranging from 4.1 to 5.9 percent in the vials from two of the three shops [6]. Reviews of unregulated melanotan use list preparation, administration and dosage among the standing open questions about these substances [1].

So the honest description of a tanning nasal spray is not that the dose is high or low. It is that no published work establishes what a spray delivers, the labelled contents of these products have been measured and found wrong, and the one route with human dosing data behind it is a needle in a clinical study from 1996 [2] [6]. A number on a bottle is a claim, not a measurement.

Moles, nevi and melanoma: what the case reports establish

Case reports describe new and darkening moles during melanotan use, and four describe melanomas arising from existing moles during or shortly after it. The review that counts them says conclusive evidence linking the two is lacking. That makes the signal real, plausible and unquantified, not proven.

A nevus is the medical word for a mole, and a dysplastic nevus is one whose cells look irregular enough under a microscope to warrant attention. The clearest case in this literature involves a 40-year-old man with a history of melanoma and multiple dysplastic nevi who self-administered a synthetic α-MSH peptide. He developed crops of new pigmented moles, many with atypical clinical and microscopic features, while pre-existing moles darkened and acquired growth features [9].

The detail that makes it persuasive is what happened next: after he stopped, the moles progressively lightened and lost their growth features [9]. Stopping the exposure reversed the effect, which is about as close as a single case can get to demonstrating that the drug was doing the driving. The authors concluded that synthetic α-MSH peptides can drive proliferation of neoplastic melanocytic cells in predisposed patients [9].

Then there are the melanoma reports. A 2014 case describes a 20-year-old woman with a suspicious black lesion in her left gluteal region and universally, intensely pigmented skin; histology confirmed melanoma, and three months earlier she had completed a three to four week course of melanotan II self-injections intended to augment sunbed tanning [10]. A 2025 report describes a 22-year-old woman who developed a mass in the anterior maxilla, the upper jaw, after using melanotan II nasal spray for tanning; it was a mucosal malignant melanoma, treated with surgical resection followed by ongoing immunotherapy [11]. The review that catalogues this literature counts four case reports of melanomas emerging from existing moles during or shortly after melanotan use [1].

Here is the part the coverage usually skips, and it cuts both ways. That same review states plainly that conclusive evidence linking these phenomena is lacking [1]. Case reports establish that something happened and that a mechanism is plausible. They cannot tell you how often it happens, because nobody counted the people who used the drug and did not get melanoma. What tips the balance from anecdote toward pharmacology is that the approved, tested, dose-controlled member of the family carries the same warning in its own label: SCENESSE may lead to darkening of pre-existing nevi because of its pharmacologic effect, and a full body skin examination twice yearly is recommended [4]. In its trials, melanocytic nevus was reported in 5 of 125 subjects on the drug against 2 of 119 on vehicle [4].

The harms that have nothing to do with skin

Because melanotan II activates melanocortin receptors without selecting between them, its published harms reach well past pigment. The case literature includes rhabdomyolysis with kidney injury, renal infarction and priapism, and one documented case required three days of intensive care after a single injection.

Rhabdomyolysis is the breakdown of muscle tissue, which floods the blood with proteins the kidneys then have to clear. A 2012 case report describes a 39-year-old man who injected 6 mg of melanotan II bought over the internet, an amount he described as six times the starting dose he had been told to use, and arrived at an emergency department two hours later sweating, anxious and aching [7].

His numbers tell the story better than adjectives can. Blood pressure 151/85, heart rate 130 peaking at 146, dilated pupils, tremor. Creatinine, a marker of kidney function, was 2.25 mg/dL, and creatine phosphokinase, the muscle-breakdown marker, was 1760 IU/L on arrival and 17,773 IU/L twelve hours later [7]. He spent three days in intensive care on intravenous fluids before both values came down, and mass spectrometry confirmed that what he had injected really was melanotan II [7].

That case is not isolated in kind. A 2020 report presents a renal infarction, a blockage of blood flow to the kidney, most likely attributed to melanotan II, and notes that rhabdomyolysis and renal failure with this peptide had been described before; the authors raise both a clotting mechanism and possible direct toxicity to kidney tissue as explanations [8]. The 2026 systematic review of tanning agents summarises the whole picture in one line: unregulated melanotan I and II use has caused serious adverse effects, including rhabdomyolysis, renal infarction, and priapism [12]. Priapism is an erection that will not resolve, and it is a urological emergency, not an anecdote about a side effect.

Set that against the safety file of the approved molecule, tested in 244 adults across three randomised, vehicle-controlled trials, where the commonest adverse reactions were implant site reaction in 21 percent and nausea in 19 percent [4]. The difference is not that one molecule is clean and one is dirty. It is that one was characterised before it was sold.

What this means if you are weighing one up

Anyone who has used a tanning peptide should have their moles checked and should tell the clinician what they used, because the pharmacology changes how a changing mole is read. The tested alternatives to melanotan II work by entirely different routes and none of them requires a needle or a nose.

The most useful thing on this page is not a verdict, it is a sentence to say in a consulting room. If you have used a tanning peptide and a mole has changed, say which product and when. The published cases turn on that timeline: the man whose moles reversed after he stopped [9], the woman whose melanoma was excised three months after a three to four week course [10]. A clinician who knows about the exposure reads a changing mole differently from one who does not, and the label of the approved drug in this family already recommends twice-yearly full body skin examination for people taking it under supervision [4].

It also matters that melanotan II is not the only way to change skin colour without ultraviolet light, and the alternatives sit on completely different pharmacology. The 2026 systematic review describes dihydroxyacetone, the active ingredient in conventional self-tanners, as producing pigmentation through the Maillard reaction, a chemical browning at the skin surface rather than anything involving a receptor [12]. It notes that forskolin stimulates melanin production independently of melanocortin receptors and has shown efficacy in animal models, and that ingested carotenoids accumulate in skin and subcutaneous fat and create a yellow-orange hue [12]. The review is candid that both of those remain underresearched in humans [12], which is the correct thing to say and the thing a product page never says.

What separates afamelanotide from melanotan II in the end is not chemistry, or not only chemistry. Afamelanotide went through three vehicle-controlled trials in 244 adults, and in the larger of the two sunlight studies the median hours in direct sunlight without pain over 180 days was 64.1 against 40.5 on vehicle [4]. That number exists because somebody ran the study. There is no equivalent number for a nasal spray, and there will not be one, because nobody selling it is going to run the trial that could produce it. If you want to see how a molecule earns a claim, our afamelanotide mastery course follows this exact family from receptor to approval, and the free foundations course starts earlier, with how peptides work at all.