Melanotan II: The Definitive Guide

What is Melanotan II?

Melanotan II (MT-II, often written MT2) is a lab-made peptide, a short chain of seven amino acids with six of them closed into a ring, that people use mainly to tan their skin without as much sun. It also causes erections and can reduce appetite.

It copies the active part of alpha-MSH, a hormone that tells the skin's pigment cells (melanocytes) to make melanin, the brown-black pigment that darkens skin. Researchers at the University of Arizona designed it in the late 1980s as a longer-lasting, more potent version of that signal, hoping a "sunless tan" could protect against skin cancer. [1], [2], [3]

The key word is investigational: no regulator has approved Melanotan II for any use. Only three small trials, in 23 men, have tested it on its own, and development moved to a close relative, bremelanotide (PT-141), which is now a separate approved medicine. Online it is also called MT-2, the "tan jab" or the "Barbie drug". [3], [4], [5], [6], [7], [8]

Typical Melanotan II Protocols

The most common protocol in the reviewed sources is a loading phase of about 250 mcg a day by subcutaneous injection, usually for 1–4 weeks or until the wanted shade appears, followed by maintenance injections of 500–1,000 mcg once or twice a week. [10], [12], [13], [14], [15], [16], [17]

Titration Changing the amount in steps

The usual approach starts with one small first dose of 100–250 mcg to see how it is tolerated, then moves to about 250 mcg a day. Some sources step up during the first week instead, for example 100 mcg for three days, 250 mcg for three days, then 500 mcg; others start as low as 50 mcg and move up to 200 mcg. [15], [18], [9]

Breaks and cycles

Loading usually ends when the wanted shade appears rather than on a fixed date. Maintenance is open-ended in most sources, lasting as long as the person wants to keep the colour. A few give a planned break: one frames use as a 4–6-week cycle followed by at least 4 weeks off, the mid example's source says some users take 4–8 weeks off after 3–6 months, and the high example's handout says to take at least 1 month off every 3 months. In practice many people stop when they are dark enough or at the end of summer. [9], [18], [10], [11], [19]

Read the units: mcg means micrograms; 1 mg equals 1,000 mcg. Loading is daily, so its weekly total is seven doses added together, and its daily total is the single dose. Maintenance doses are bigger but less frequent, so a 1,000 mcg maintenance injection once a week is less in a week than 250 mcg every day. Nasal sprays are not included; their amounts cannot be compared (see routes).

Low, mid and high are alternatives, not steps to move through, and each row keeps its source's amounts and durations together. These schedules come from dosing websites and forum practice rather than clinical trials, which only tested a handful of weight-based injections; the cited references give the full details. [3], [20]

Cautions for every schedule above. None of these amounts has been tested for safety. The human studies gave a few weight-based injections over two weeks at most, and nausea was common and sometimes severe. Case reports describe new or darker moles within a day to a week of starting, melanoma (several alongside sunbeds, which cause melanoma on their own) and erections lasting hours that needed drainage or surgery, one after a 2 mg injection; the cause is unproven. An erection lasting more than four hours or a seizure needs urgent medical care. Vials labelled 10 mg held 4.32–8.84 mg when tested, so the real amount in each dose is uncertain. [3], [4], [21], [22], [23], [24], [25], [26] People with many or unusual moles or a history of melanoma, high blood pressure or heart disease, diabetes, pregnancy or breastfeeding, and anyone under 18 should read who should be especially cautious first.

Where protocols differ: loading, dose ceilings, sun exposure and nasal sprays ↓

What is Melanotan II commonly used for?

Most people look into Melanotan II because they want a tan and do not tan easily: fair skin that burns, or a holiday or competition coming up. Its effects on erections and appetite are discussed too, both as a reason some people use it and as side effects. [28], [29], [24]

Those reasons are real, but only tanning and erections were measured in people, in three short studies of men. The sections below separate what was measured from what people hope for. [3], [30]

Getting a tan with less sun

This is what Melanotan II was built for. In the first human study, two of three healthy men had measurably darker skin on the face, upper body and buttocks one week after dosing ended, after only about five low injections every other day. The buttocks are rarely sun-exposed, which suggests the darkening did not depend only on sunlight. [3]

People online describe colour within days to about two weeks, usually faster and darker with sun or sunbeds, and the face and hands often darkening before the body. Some describe freckles and moles darkening instead of an even tan. [31], [32], [33]

Does a Melanotan II tan protect against sunburn?

That has not been shown. No study measured sunburn protection with Melanotan II. A study often quoted on dosing pages as Melanotan II evidence tested Melanotan I, a different drug. Australia's medicines regulator warns that an induced tan does not replace sunscreen, and some pages still claim sunburn protection that no study supports. [27], [13], [34], [35]

Libido and erections

Melanotan II reliably caused erections in the small human studies, even without sexual stimulation. In 10 men with erectile problems of psychological origin, 8 developed erections after one injection; in 10 men with physical risk factors, erections followed 12 of 19 injections compared with 1 of 21 placebo injections, and sexual desire rose. [30], [4]

That effect led to bremelanotide (PT-141), a close relative now approved in the United States as an as-needed injection for premenopausal women with acquired, generalized hypoactive sexual desire disorder (persistently low sexual desire that causes distress). Online, people report strong and sometimes unwanted erections, while others notice no change. The experience section covers both. [5], [6]

Appetite and weight

Reduced appetite was a side effect in the erection study. In rats and mice, Melanotan II cuts food intake through the brain's MC4R appetite pathway, but the effect fades within days of continuous dosing. It has never been tested as a weight-loss treatment in people. [30], [36], [37]

Other uses you may come across

Hair and beard darkening appears in community posts, but no study has examined it. Skin-cancer prevention was the original research goal and was never shown; the cancer question is still open. A 2026 vitiligo trial registration that names Melanotan II has features of a placeholder record, so it should not be read as an active trial. [19], [2], [38]

Where do Melanotan II protocols differ?

The recurring amounts are easier to summarize than the details around them. Pages disagree about loading, how high to go, whether sun is needed and how long to continue. Here is what those differences mean when reading a protocol.

Is the number for one dose, one day or one week?

A bigger number can be a smaller exposure. 250 mcg every day is 1,750 mcg in a week; 500 mcg twice a week is 1,000 mcg. Maintenance doses look large because they are spread out, so compare weekly totals, as the table above does. [10]

Doserly

One week of loading versus one week of maintenance

Loading week

Loading week: 250 mcg once daily, 7 injections, 1,750 mcg in the week. Once daily, 2–4 weeks.

Maintenance week

Maintenance week: 500–1,000 mcg once or twice, 500–2,000 mcg in the week. Thursday is optional.

Each dot is one subcutaneous injection.

A bigger maintenance injection can add up to a similar or smaller weekly amount than daily loading. Compare weekly totals, not the size of one injection.

Mid example from a dosing website, not a clinical trial. Amounts in micrograms (mcg).

Is a loading phase needed?

No trial has shown that loading is needed, but most dosing sources include it: of the 28 independent sources compared here, 26 describe a loading phase, and most of those make it daily. A few say the opposite, including one seller's page that calls loading unnecessary while still giving a ten-day daily load. Community education groups disagree too: one advises no loading and no more than three doses a week, while others build in 1–3 weeks of daily doses. [39], [9], [12]

The loading idea is older than any of these pages. Bodybuilding forums described "loading" then "maintenance" by 2006–2011, and a 2012 UK public-health report recorded the same pattern. It came from user practice, not from a trial. [40], [41], [20]

How high do sources go?

Loading doses range from 50–250 mcg on cautious pages to 500–1,000 mcg a day on others, and maintenance from 50–100 mcg to 1,000 mcg. Community education groups set different ceilings too, from about 250 mcg to 1 mg. [18], [42], [11], [39]

Two pages that share one dosing table say not to exceed 2 mg a day. No study set that limit; the human studies never tested daily use at all. [43], [44], [3]

None of these is a tested safe maximum. The case reports include a prolonged erection needing surgery after a 2 mg injection and severe toxicity after 6 mg, and online accounts at 500–1,000 mcg include over-darkening and moles turning black. [24], [45], [46]

Do you need sun or a sunbed?

Pages contradict each other: of the 30 pages first compared on this point, 13 say ultraviolet (UV) light is required, 5 say it is not, 2 say it only speeds things up and 10 do not say. In the first human study, skin darkened without any planned sun exposure. [3], [15], [39]

This matters because sunbeds carry their own skin-cancer risk. In one survey of 104 patients at an Irish mole clinic, those who used tan-enhancing products such as melanotan used sunbeds more often than those who didn't. [29], [47]

How long, and are breaks needed?

There is no tested course length. Loading lasts until the wanted colour (1–4 weeks on most dosing pages), and maintenance is often open-ended or seasonal. Community education groups describe 4–6 weeks on and 8–12 weeks off, while others dose "as needed" before sun. Some long-term users describe years of seasonal or year-round use. [12], [48], [19]

Why do some sites give a dose per kilogram of body weight?

The human studies used 0.01–0.03 mg per kilogram (0.025 mg/kg is 1.75 mg for a 70 kg adult) as single injections a few times. Some pages borrow that figure for a daily cosmetic schedule, and one converts 0.025 mg/kg for an 80 kg person to 0.2 mg when the correct figure is 2 mg. Another gives a range of up to 0.05 mg/kg, higher than any dose given in a human study. Those trial doses were not tested as a weeks-long routine. [3], [35], [10], [16]

How do micrograms convert to syringe units?

Melanotan II is usually sold as a powder in a 10 mg vial that is mixed with sterile water before injection. On a U-100 insulin syringe, units measure volume, not drug. For example, 10 mg (10,000 mcg) mixed into 2 mL gives 5,000 mcg per mL, or 50 mcg per unit, so 250 mcg would be 5 units. The same 250 mcg is 12.5 units if the vial is mixed with 5 mL. Doserly's reconstitution calculator works this out for any vial and shows each step.

Copied unit numbers go wrong often: one page says 10 units is 100 mcg at a strength where it is actually 1,000 mcg. [49]

What happens when you stop Melanotan II?

The 1996 study checked skin colour one week after the last dose, and no study has looked for withdrawal effects or a rebound. Case reports follow some people for up to about three months after stopping, but sunbeds and other factors limit what they can show. [3], [50], [51]

• The tan. In the 1996 study, darker skin was still measurable one week after the last injection; nobody measured how long it lasted after that. In a similar study of Melanotan I, a different drug, the tan peaked about a week after the last dose and was still visible three weeks later. People online describe the colour fading over weeks to months. [3], [52], [19], [46]
• Moles and other pigment. Case reports describe darkened moles lightening gradually after stopping, including in a 16-year-old whose skin and moles were much paler three months later, although she still used a solarium. Not everything fades: in one man, brown patches inside the cheeks had nearly gone within a month, but his gum colour, which may already have been partly darker before, had not fully cleared at three months. The label of the approved relative bremelanotide likewise says its dark patches were not confirmed to clear in every patient after stopping. [53], [50], [51], [6]
• Appetite. In rats given Melanotan II continuously into the brain, the drop in eating faded within a few days even though dosing continued, and it returned when dosing restarted after a break. No one has measured this in people. [54], [37]
• Other effects. Public accounts point both ways: a racing heart settling within about two weeks, or libido recovering over months, but also erection problems and dark freckles still there months later. [55], [56], [57], [46]

The breaks and "off seasons" that protocols describe are a user convention, not a response to known withdrawal effects.

Do nasal sprays and injections behave the same way?

No one knows, because Melanotan II has never been measured in human blood by any route: there is no human pharmacokinetics study. A subcutaneous injection places it in the fatty layer under the skin, from where it is absorbed into the blood. An intranasal spray has to cross the lining of the nose, and how much gets through has not been studied in people. [3], [65]

The animal hints point to lower exposure. In rats, Melanotan II given into a vein switched on hormone-producing nerve cells in the hypothalamus (a small brain area that controls hormones, appetite and body temperature), while the same peptide given into the nose did not. Early rat work also found that only 4.6% reached the blood when it was swallowed (its oral bioavailability). [66], [2]

Are nasal spray doses reliable?

No. Many ready-made sprays do not say how much is in each spray, so people count sprays instead of micrograms. When Australia's regulator tested five seized bottles of one spray product labelled 30 mg, they held anywhere from 22 mg to 54 mg of Melanotan II each. One spray seller calculates "50% absorption" with no data behind it. [64], [63]

Nasal use is not free of reported harm. A 22-year-old developed a melanoma inside her mouth after using a Melanotan II nasal spray, and a stroke has been reported after a melanotan nasal spray in a conference abstract. Neither report proves the spray caused the problem. [67], [68]

How long does Melanotan II stay in the body?

This has not been measured in people, so its half-life is unknown. A rat study measured how blood levels fell after an injection into a vein, and a mouse study found only low levels reached the brain. Claims like "it stays in your system for 36 hours" have no human measurement behind them. [69], [70], [71]

Some dosing pages do quote human half-life figures, such as under an hour to about two hours. Those numbers come from a 1997 study of Melanotan I, a different drug. [61], [52]

How long the colour lasts is a separate question from how long the drug stays in the body. People describe colour fading over weeks to months after stopping, while some freckles and mouth pigment persist. [19], [51]

How should Melanotan II be stored, and how long does it last?

No one knows for certain. Melanotan II is not an approved medicine, so no label sets storage conditions or expiry dates, and none has been validated for a purchased powder, mixed vial or nasal spray. What exists is one early laboratory study, a regulator's comment and seller claims. [72], [73], [74]

• In solution. A 1994 laboratory study dissolved Melanotan II in buffered water at room temperature (25 °C) and estimated its shelf life at 27 hours. It broke down faster at higher temperatures and higher phosphate-buffer concentrations, and was most stable at a mildly acidic pH of about 5. That was a formulation experiment, not a test of a mixed vial kept in a fridge. [73]
• Powder and mixed vials. Melanotan II is usually sold as a freeze-dried powder. Dosing pages disagree on how to keep it: one says to store the powder at −20 °C or below, another below 25 °C. Once it is mixed with liquid (reconstituted), they agree on a fridge at 2–8 °C but give different limits, such as "use within 1–2 weeks" or "use within 28 days". None of them cites a stability test for Melanotan II. [44], [62], [43]
• Vials used over weeks. When Australia's medicines regulator made Melanotan II prescription-only in 2018, it noted that mixed multi-dose vials used over several weeks "pose a stability issue and further increase the infection risk". [74]
• What is actually in the vial. Seized products tested in Belgium came with no storage or handling instructions, and the tests found related impurities, including possible breakdown products. The product analyses cited here measured content and impurities, not sterility (freedom from germs), and no data were found on how long an opened nasal spray keeps its strength. [75], [26]

The approved relatives have tested instructions for their own finished products: a fridge (2–8 °C) and protection from light for the afamelanotide implant, and no higher than 25 °C, not frozen and protected from light for the bremelanotide autoinjector. These do not transfer to a home-mixed Melanotan II vial. This guide does not cover mixing or injection technique; the Academy note below covers practical handling. [76], [6]

What do we actually know about Melanotan II in people?

Very little. Three small studies from the University of Arizona, published between 1996 and 2000, are the only human research on Melanotan II by itself. Together they included 23 men, and used weight-based subcutaneous injections given over two weeks at most. [3], [30], [4]

What did the human studies find?

A later review by the same team pooled the 20 men from the two erection studies; it is a re-analysis, not a new group. One cancer study in 30 adults, most of them women, gave 10 mcg of Melanotan II as one part of a multi-drug regimen, so nothing in it can be credited to Melanotan II alone. [77], [78]

Doserly

What the studies gave versus what websites describe

Tanning pilot

Tanning pilot: 0.01 mg/kg start (700 mcg for 70 kg) up to 0.03 mg/kg (2,100 mcg), about 5 injections over 2 weeks. The top dose caused grade II sleepiness in 1 of 2 men.

Erection trials

0.025 mg/kg (1,750 mcg for 70 kg), one or two injections.

Dosing websites

250 mcg daily for 1–4 weeks or until the wanted shade, then 500–1,000 mcg once or twice a week, open-ended.

The only human studies used a few weight-based injections over two weeks at most; website schedules use smaller fixed doses given daily for weeks, then indefinitely. Neither pattern has been tested for long-term safety.

Study doses were set per kilogram of body weight; milligram figures are arithmetic for a 70 kg adult, not dose advice. Website amounts describe practice, not tested regimens.

What does the approved relative tell us?

Bremelanotide is the best-studied drug built on the same ring, and its label is useful context, not a Melanotan II dose guide. In its trials, 40% of women had nausea, blood pressure rose briefly by up to 6/3 mmHg, and 1% developed dark patches on the face, gums or breasts at up to eight doses a month, with higher risk in darker skin and with daily dosing. The label limits use to one dose in 24 hours and advises against more than eight a month. Melanotan II users often inject daily. [6]

What didn't these studies test?

Almost everything people do with it now. No study has tested Melanotan II on its own in women, and there are none of nasal sprays, none of the fixed-microgram loading and maintenance schedules, none lasting longer than about two weeks, and none measuring sun protection, mole changes or blood levels. A 2026 trial registration for vitiligo appears to be a placeholder: its sponsor filed a BPC-157 record on the same day with the same contact, and another of its records is labelled a mock study. [79], [38]

How does Melanotan II work?

Melanotan II switches on several melanocortin receptors, the family of sensors that respond to alpha-MSH. In cell studies it activates four of them (MC1R, MC3R, MC4R and MC5R) at very low concentrations. Because it is not selective, activity at several receptors may help explain why tanning, erections, nausea and appetite changes tend to come together; the brain findings below come from animal studies. Websites often add that it leaves alone MC2R, the receptor for adrenocorticotropic hormone (ACTH), a stress-hormone signal; the receptor studies cited here did not report a result for that receptor. [80], [81], [82]

How does it darken skin?

On melanocytes, the MC1R receptor controls which melanin is made. Switching it on shifts production toward dark eumelanin instead of the reddish kind. The cyclic design made Melanotan II far more potent and longer-lasting than natural alpha-MSH in early lab tests, and it darkened a dog's coat and the two men's skin. [1], [83], [84], [3]

Why do moles and freckles darken?

Moles and freckles are places where pigment cells are already clustered or especially active. A signal that tells every melanocyte to make more pigment makes these spots darker and more visible, and case reports describe new moles appearing within a day to a week. Whether some of these are brand-new or were too faint to see before is debated; the reports show both darkening and new spots, including some unusual-looking ones. [21], [22], [85], [86]

Why does it cause erections, nausea and appetite changes?

These come from the brain and spinal cord. In animal studies using rats, Melanotan II triggers erections by acting on melanocortin receptors in the brain and spinal cord, not in the penis itself. In mice, its effect on appetite needs the MC4R receptor; in rats, giving it into the fluid space by the brainstem also cut food intake for a day. In rats it also produces a learned aversion to a flavour paired with it, a laboratory sign of nausea. [87], [88], [36], [89], [90], [91]

What else does it do in animals?

In awake mice it raised blood pressure and, even more, heart rate through the nervous system. In mice it also caused a sharp temporary drop in body temperature by releasing histamine from immune cells. These are animal findings. The histamine release is one possible, untested explanation for the flushing people describe, and the heart-rate rise fits the racing heart described in some case reports. [92], [93], [45]

What are the risks and unanswered questions?

Is Melanotan II safe?

No one has shown that it is, and published case reports describe serious harms. The safety evidence from studies is limited to 23 men given injections over two weeks at most, in whom nausea was common and sometimes severe. Rare or slow problems, like changes in moles, could not show up in studies that small and short. [3], [4]

The US Food and Drug Administration (FDA) says published case reports describe serious adverse events with Melanotan II, including melanoma, a brain-swelling syndrome called posterior reversible encephalopathy syndrome (PRES), a "fight or flight" overdrive (sympathomimetic toxicity) and priapism. It also warns that compounded products could trigger an immune reaction, because the peptide can clump together or carry related impurities. Australia's medicines regulator lists headache, nausea, vomiting, loss of appetite and facial redness as common effects of melanotan products, and says there have been reports of increased moles and freckles, kidney problems and brain swelling with Melanotan II. [94], [34]

Reviews from 2014 and 2026 covering both Melanotan I and II describe the same range of reported harms, from nausea, darker moles and yawning to whole-body toxicity, kidney damage, priapism and melanoma. [95], [96]

What problems have been reported?

These are case reports: single patients whose doctors published what happened. They show what can happen, not how often. The product was rarely tested, several skin reports involved sunbeds, and reports marked † describe the product only as "melanotan" without confirming the type.

Does Melanotan II cause skin cancer?

Nobody knows. A 2017 review counted four published reports of melanoma arising during or soon after melanotan use and concluded that conclusive evidence linking them is lacking; more cases have been published since. Several of the skin melanoma cases involved sunbeds, which cause melanoma on their own. [65], [23], [97]

There is a practical problem too. Dermatologists report that Melanotan II changes how moles look under magnification, making it harder to tell a harmless mole from melanoma. In contrast, a mouse study found Melanotan II applied to the skin slowed the growth of an existing melanoma, which says nothing about the risk of new melanomas in people. Claims that it "protects against skin cancer" are not supported. [104], [7], [105], [34]

In July 2026 the US Skin Cancer Foundation warned against Melanotan II, saying the rapid mole changes it causes can make skin cancer harder to detect and that, while case reports cannot prove cause, they warrant caution. [72]

Could product quality change the risk?

Yes. When researchers bought vials labelled 10 mg from three online shops, they held 4.32–8.84 mg, and two shops' vials contained 4.1–5.9% unknown impurities. A seized vial tested in Belgium was about 30% pure. Needle sharing and contaminated products are also recurring concerns in user forums. [26], [106], [28]

Is Melanotan II legal? Is it FDA-approved?

Checked September 23, 2026. Rules differ by country and change quickly. A "research use only" label does not make a product legal to sell or safe to use.

United States. Melanotan II is not an FDA-approved medicine. The key steps:

• Before 2023. The FDA warned a company selling it as a tanning injection in 2007, lists Melanotan I and II in an import alert on unapproved drugs sold online as "research" products, and in 2020 told a compounding pharmacy that Melanotan II was not an eligible ingredient. [107], [108], [109]
• September 2023. The FDA placed it in the compounding category for substances that raise significant safety concerns. [110]
• April 2026. It moved to "nominated but withdrawn" because the people who proposed it withdrew the nomination, not because the FDA judged it safe. The FDA's safety statement about melanoma, PRES, sympathomimetic toxicity and priapism remains on its website. [111], [94]
• Next. Melanotan II is on the agenda of an FDA advisory committee meeting to be held before the end of February 2027. No decision has been made, and compounded products would still not be FDA-approved. [112]

Canada. Health Canada has not authorized it. Since 2025 it has named Melanotan II in several advisories about seized unauthorized peptides, most recently in April 2026, when it listed "Melanotan I and II" among seized injectable peptides. [113], [114], [115], [116]

Australia. Melanotan II has been a prescription-only (Schedule 4) substance since 1 June 2018, and no product is approved. The medicines regulator warned against melanotan tanning products in January 2025, issued 27 fines totalling A$101,412 to one New South Wales individual for allegedly supplying Melanotan II in May 2026, and reported inconsistently dosed nasal sprays in August 2026. [117], [34], [118], [64]

United Kingdom and Europe. It is unlicensed in the United Kingdom. The medicines regulator treats injectable products as medicines, which cannot be sold without a licence, while nasal sprays count as medicines only when sold with medical claims. It received 16 suspected adverse-reaction reports between 2012 and 2022. Ireland, Denmark and Norway have issued warnings or enforcement orders. The only approved relative in the European Union is afamelanotide (Scenesse). [67], [119], [120], [121], [122], [123]

Is Melanotan II banned in sport? Does it show up on a drug test?

It is not named on the World Anti-Doping Agency's 2026 list, or on the 2027 list published in September 2026, but their S0 category bans drugs with no current approval for human therapeutic use that no other category covers, and Melanotan II appears to fall under it. Competitive athletes should assume it is prohibited at all times. Researchers developed a laboratory method that measures it in rabbit urine samples with known amounts added, but no one has published whether, or for how long, a test can detect it after use in people. [124], [125], [126]

Who should be especially cautious?

Most of these groups have never been studied. That is a reason for caution, not proof of harm.

• People with many moles, unusual moles, or a personal or family history of melanoma. Mole changes are the most reported problem, and one case involved a teenager with an inherited many-mole syndrome. [50], [97]
• People with high blood pressure or heart disease. Animal studies show rises in heart rate and blood pressure, and the approved relative's label rules out use with uncontrolled high blood pressure or known heart disease. [92], [6]
• Men at risk of priapism, including those using other erection medicines. [24]
• People with diabetes. A 2025 case report describes a man with type 1 diabetes admitted with vomiting, very high blood sugar and ketones, which his doctors linked to Melanotan II raising his cortisol. One case with an untested product cannot prove cause. [102]
• Pregnancy and breastfeeding. No data.
• Under 18. No studies, yet published cases include a 16-year-old. This guide is written for adults. [50]
• Competitive athletes, because of the S0 rule. [124]

Has Melanotan II been tested alongside other medicines?

Not in people. The closest guide is its approved relative: bremelanotide can slow stomach emptying and change how well some tablets are absorbed, and it sharply lowers blood levels of oral naltrexone. Some people take Melanotan II alongside weight-loss injections such as semaglutide; that combination has not been studied, and in one public account severe vomiting followed a week when both were used. Bring a complete list of everything you take to a pharmacist or doctor. [6], [127]

What should be monitored while using Melanotan II?

There is no official monitoring plan, because no regulator has approved Melanotan II or written a label for it. What exists is a record of what the small studies measured, what case reports found, and what the labels of its approved relatives ask for. It can help you prepare questions for a clinician; it is not a personal testing plan.

What did the human studies check?

• The tanning pilot measured skin colour with a light-reflectance device and by eye one week after dosing ended, and recorded side effects such as nausea, sleepiness and erections. [3]
• The erection studies recorded erections for six hours with a monitor worn on the penis, and used questionnaires for sexual desire and side effects. [30], [4]
• Blood pressure, heart tracings and blood tests are not reported in the published summaries, so the studies cannot show whether these stayed normal. [3], [4]

What do the approved relatives' labels ask for?

These labels are for different drugs at different doses, shown because they act on the same receptor family.

• Afamelanotide (Scenesse), the approved form of Melanotan I, recommends a full-body skin examination twice a year to monitor existing and new pigmented spots, because it can darken moles and freckles. [76]
• Bremelanotide (Vyleesi), the approved relative with the same ring, raises blood pressure and lowers heart rate for a while after each dose. Its label asks prescribers to assess heart risk before and during treatment and to make sure blood pressure is well controlled, and it must not be used with uncontrolled high blood pressure or known heart disease. [6]

The US Skin Cancer Foundation advises anyone with changing moles, skin pigment or skin-cancer concerns to discuss them with a board-certified dermatologist (a skin specialist). [72]

Which signals matter, and why?

Some signals, such as an erection lasting more than four hours or a seizure, need urgent medical care rather than tracking. [25], [100]

Most of these come from single case reports and related drugs, not from monitoring studies of Melanotan II, so they show what doctors have flagged rather than what a person will experience.

What do people in public communities report?

Public forums contain fast tans, disappointments, and a steady stream of mole, nausea and erection reports. The most useful posts say what was taken, how much sun was involved and what happened weeks later. These are selected discussions, not a survey of everyone who has tried it. [28]

What do the positive reports look like?

The typical success story is a deep tan within one to three weeks, often alongside sun or sunbeds, and colour that lasts months. One long-term user described tanning over about six summers at 100–250 mcg on sun days, keeping colour for three to four months, with few mole changes at those low doses. Another, dosing at up to 1,000 mcg a day with an hour of strong sun daily, tanned heavily within a week but was "covered in moles" around the neck. [33], [31]

How long does the colour last?

People describe the tan fading over weeks to months after stopping, sometimes leaving a slightly darker baseline. Long-term users describe years of seasonal use. Freckles, mole darkening, lip pigment and dark spots at injection sites can outlast the tan, in some accounts by a year or more. [19], [128], [46]

Does everyone tan?

No. One person reported no colour and no side effects after four doses with UV each time (the post gives both 500 mcg per dose and a 1,200 mcg total); another saw little colour after a month of doses and sun, only darker moles, and later suspected a fake product. Very fair, freckle-prone people often describe freckles darkening long before any even tan. [129], [130], [131]

What about moles, freckles and spots?

This is the most common worry. Accounts describe new or darker moles within days, sometimes at doses as low as 75 mcg, blue or dark dots on the lips by day six, and dark spots at injection sites lasting months. Follow-ups differ: in one lip-pigment thread the spots faded after stopping, while others report marks that never fully cleared. [31], [132], [128], [133]

Medical follow-up is uncommon but telling. One person had several darkened moles booked for removal after mole mapping; in another thread, a biopsied mole was benign, while a commenter who used sunbeds twice weekly reported a melanoma found at a yearly skin check. None of these can show cause. [134], [135]

Community education groups are split on this. Some teaching says Melanotan II only darkens moles that were already there and protects against skin cancer; other material in the same groups warns of new lesions and cites the melanoma reports. The published case reports describe new moles, and regulators say an induced tan is not protection. [22], [34]

What about nausea and flushing?

Nausea is the most common complaint. Many describe it starting within seconds to minutes of an injection and lasting from under an hour to overnight; some find it eases after the first few doses, others stop because of it. One person with incapacitating nausea at only 50 mcg later had severe vomiting during a week when they also started semaglutide. Workarounds (eating first, dosing at bedtime, antihistamines, anti-sickness tablets, nasal use) are untested and contradict each other. [136], [71], [127]

What about erections and libido?

Men often report strong spontaneous erections, sometimes for hours and at inconvenient times, and some women describe a much stronger sex drive. Others notice nothing. A smaller group describe the opposite over time: weaker erections or lower libido between doses that improved months after stopping. [71], [56], [57]

What about heart, blood pressure and kidney reports?

A minority describe a racing heart, palpitations or high blood pressure, such as a reading of 170/90 soon after starting 100 mcg. In one thread, a person on 100–175 mcg a day stopped because of a racing heart that settled over about two weeks, but about 50 new dark freckles remained. Another reported blood-test signs of reduced kidney function that recovered after stopping, while others in the same thread had normal results. These accounts involve unverified products and other drugs, but they echo the case reports. [55], [137], [138]

How can you judge a Melanotan II story?

Useful questions: How much was taken, and was it micrograms or "units" from an unknown mix? How much sun or sunbed use was involved? Were other drugs, such as testosterone or weight-loss injections, taken at the same time? What happened to moles, and did a doctor examine them? Did the person post again weeks later? A tan appearing proves little about safety; mole changes can take months to judge. [139], [140]

How does Melanotan II compare with Melanotan I and PT-141?

These three melanocortin peptides are sold side by side online and often confused. For Melanotan II the schedule below comes from protocol sources, not tested doses; for the other two it comes from the approved medicine's label.

Doserly

Melanotan II and its relatives

Alpha-MSH

Natural hormone · 13 amino acids, straight chain · Made by the body; tells pigment cells to make melanin · Natural hormone (not a medicine)

Melanotan I (afamelanotide)

MT-I; approved as Scenesse · 13 amino acids, straight chain · Approved form is an implant for adults with erythropoietic protoporphyria (a rare light-sensitivity disorder) · Scenesse implant approved: EU 2014, US 2019

Melanotan II

MT-II, MT2, ‘tan jab’, ‘Barbie drug’ · 7 amino acids, 6 in a ring; ends in an amide (-NH₂) · Sold online for tanning, libido and appetite · Not approved anywhere

Bremelanotide (PT-141)

Approved as Vyleesi · Same 7 amino acids and ring; ends in an acid (-OH) · 1.75 mg injection as needed for low sexual desire (acquired, generalized) in premenopausal women; no more than 1 dose in 24 hours or 8 a month · FDA-approved 2019 (Vyleesi)

Four related molecules differ in structure, use and approval. Similar structure does not transfer approval, dose or safety.

Structures simplified. Approval of a relative does not apply to Melanotan II.

The real differences are in evidence and approval. Melanotan I and PT-141 each have one approved medical use, backed by controlled trials, a tested dose and a label; Melanotan II has none of these. No study has compared the three in people, so the table cannot say which works better or is safer.

Some websites and education materials say PT-141 is what Melanotan II turns into inside the body. A 2020 mouse study did find a breakdown product in tissue that has lost the amide end, which is chemically the same molecule as PT-141. How much of it forms in people has never been measured, and PT-141 is made, tested and approved as its own drug with its own dose. [60], [143], [6] Online "research" products are not the approved medicines: an FDA import alert covers Melanotan I and II imported as research products and sold online, and police seizures have included both Melanotan II and bremelanotide. [108], [144]

Common questions about Melanotan II

How long does Melanotan II take to work?

Colour usually appears within days to about two weeks in public accounts, faster with sun. In the first study, darker skin was measured a week after about five injections over two weeks. There is no dependable timetable, and some people see little change. [3], [31], [129] See what people report.

Do Melanotan II dosing schedules come from clinical trials?

No. The trials gave a few weight-based injections (0.01–0.03 mg per kilogram) over two weeks at most. Daily loading and weekly maintenance came from bodybuilding forums by 2006–2011, and no study has tested that pattern. [3], [30], [41], [20] See where protocols differ.

Does Melanotan II protect you from sunburn or skin cancer?

No study has shown either. Its developers hoped it might, but light protection has only been studied with its relative Melanotan I, whose approved form is an implant for a rare light-sensitivity disorder. Regulators say an induced tan does not replace sunscreen, and melanoma cases have been reported in users. [2], [123], [34], [65] See the cancer question.

Is Melanotan II the same as PT-141 or Melanotan I?

No. PT-141 (bremelanotide) shares its seven amino acids and ring but has a different end and its own approved label and dose. Melanotan I is a longer, straight-chain peptide, and its approved form (afamelanotide) is an implant for a rare light-sensitivity disorder. [6], [5] See how the three compare, or read the Doserly guides to PT-141 and Melanotan I.

Will the moles and freckles go away if I stop?

Sometimes. Public accounts describe some darkened spots fading over weeks to months and others persisting; a case report found cheek pigment faded within a month while gum pigment remained at three months. Any new or changing mole is worth showing to a doctor, whatever the cause. [51], [46], [133] See what happens when you stop.

Can you take Melanotan II with semaglutide or tirzepatide?

The combination has never been studied. Nausea is already common with Melanotan II, and in one public account severe vomiting followed a week when semaglutide was used at the same time; the account cannot show which drug was responsible. Another person injected Melanotan II by mistake instead of tirzepatide. [127], [139] See the semaglutide and tirzepatide guides.

Is it legal to buy Melanotan II?

It is not approved as a medicine anywhere, and the rules on selling and buying it differ by country. It is not FDA-approved in the United States, has not been authorized for sale in Canada, is prescription-only in Australia and is unlicensed in the United Kingdom. A "research use only" label does not make a product legal to sell for human use. [94], [116], [117], [119] See the dated legal-status summary.

Is a higher dose or a longer course more likely to work?

The evidence cannot establish that. Higher doses mainly show up in reports of over-darkening, blackened moles and severe side effects, and no course length has been tested. The studies used a few injections over two weeks at most. [45], [46], [3]

Glossary

Plain explanations of the route, dosing, skin and research terms used in this guide. Underlined terms in the text link here.

Adverse event

A harmful or unwanted medical event reported after someone used a treatment. A report alone does not prove the treatment caused it.

Alpha-MSH

Alpha-melanocyte-stimulating hormone, a natural hormone that tells pigment cells to make melanin. Melanotan II copies its active core.

Amino acid

A small chemical building block. Chains of amino acids make up peptides and proteins.

Animal study

Research in animals such as rats or mice. It shows what a substance does in a living body, but results in people can differ.

Bioavailability

How much of a dose reaches the bloodstream in a usable form. It depends heavily on the route.

Case report

A published description of what happened to one patient or a few. It can reveal a possible problem but cannot show how often it happens or prove the cause.

Cell study (in vitro)

Research on cells grown in a dish. It gives early clues about biology, but it is far from proof of benefit in people.

Compounding

When a pharmacy prepares a customized medicine from individual ingredients. In the US, federal lists control which bulk ingredients pharmacies may use.

Controlled trial

A study that compares people who receive a treatment with people who do not, often receiving a placebo instead. Randomly assigning people to each group makes the comparison fairer.

Course and cycle

A course is the period of repeated use, such as six weeks. A cycle is a course plus a planned break before any further use.

Crossover study

A study in which each person receives both the treatment and the placebo at different times, so each acts as their own comparison.

Daily total

All the amounts given in one day, added together. For example, 250 mcg twice daily is a 500 mcg daily total.

Dose (amount each time)

The amount given on one occasion. A protocol lists both the dose and how often it is given.

Eumelanin

The dark brown-black form of melanin. The other main form, pheomelanin, is reddish-yellow.

Freeze-dried (lyophilized)

Dried by freezing and removing the water, leaving a powder. Most Melanotan II is sold this way and mixed with liquid before injection.

Half-life

The time it takes for the measured level of a substance in the blood to fall by half. It is not the same as how long an effect lasts.

Intranasal

Sprayed into the nose to be absorbed through its lining.

Investigational

Still being studied and not approved by a regulator, such as the FDA, to treat any condition.

Loading phase

A first stretch of more frequent doses, here usually daily, meant to build up an effect quickly before switching to less frequent doses.

Maintenance phase

Less frequent doses after loading, meant to keep an effect going. For Melanotan II, usually once or twice a week.

mcg and mg

Micrograms and milligrams. 1 mg equals 1,000 mcg. Melanotan II protocol amounts are usually written in mcg.

Melanocortin receptors (MC1R–MC5R)

A family of five sensors that respond to alpha-MSH and related hormones. MC1R on pigment cells controls skin colour; MC3R and MC4R in the brain are linked to appetite and sexual function.

Melanocyte

A pigment cell at the base of the outer skin layer that makes melanin and passes it to nearby skin cells.

Melanoma

A cancer that starts in pigment cells. It can arise in a mole or in normal-looking skin, and more rarely inside the mouth or elsewhere.

Mole (naevus)

A cluster of pigment cells in the skin. Most are harmless; a new, changing or unusual mole should be checked by a doctor.

Peptide

A short chain of amino acids. Melanotan II is a chain of seven, six of which are closed into a ring.

Pharmacokinetics

How the body absorbs, moves, breaks down and removes a substance.

Placebo

A dummy treatment with no active ingredient, used as a comparison in studies.

Preclinical research

Studies done before research in people: cell studies and animal studies.

Priapism

An erection that lasts for hours without sexual arousal, usually defined as more than four hours. It is a medical emergency that can permanently damage erectile tissue.

Reconstitution

Mixing a freeze-dried powder with a liquid so it can be measured and injected. The amount of peptide in the vial and the volume of liquid added together set how much each syringe unit holds.

Research use only

A label on products sold for laboratory research. It does not mean a product is approved, tested for human use or legal to sell as a medicine.

Rhabdomyolysis

Rapid breakdown of muscle tissue that releases proteins into the blood and can damage the kidneys.

Schedule 4 (Australia)

Australia's prescription-only medicine category. Melanotan II has been listed there since 1 June 2018.

Shelf life

How long a product keeps enough of its strength to be used under stated storage conditions. In laboratory stability studies it usually means the time until 10% has broken down.

Subcutaneous (SC)

Injected into the fatty layer just under the skin. This is the route most Melanotan II protocol descriptions use.

Sympathomimetic toxicity

Overactivation of the body's fight-or-flight system, causing a racing heart, sweating, widened pupils, tremor and anxiety.

Syringe units

Markings on an insulin syringe that measure volume. On a U-100 syringe, 100 units equal 1 mL. The amount of drug per unit depends on the vial's concentration.

Titration

Adjusting a dose in steps, usually starting lower and increasing if needed.

Withdrawal and rebound

Withdrawal effects are symptoms caused by stopping a substance. A rebound is a problem returning worse than before after stopping. Neither has been studied for Melanotan II in people.

WADA

The World Anti-Doping Agency, which publishes the list of substances banned in sport.

Explore more of the research

Go deeper into the animal and laboratory experiments behind the mechanism claims.

Across this guide, the citations include 60 original scientific papers: 26 cell and animal papers, 28 human studies and case reports, and 6 laboratory analyses of products, stability and detection. The optional library below summarizes selected animal papers by question. Paper counts are not counts of independent research teams: many early studies come from the same University of Arizona group.

In the route details, intraperitoneal means into the abdominal cavity; intracerebroventricular, into fluid spaces of the brain; intravenous, into a vein.

How this guide was researched

This guide is built from a thorough review of the sources cited throughout it: published scientific studies, case reports, registered clinical-trial records, regulatory documents and published protocol descriptions. We also reviewed public online forums and community education groups where people describe their own experiences with Melanotan II.

The guide cites 148 sources, including 60 original scientific papers. Each type of source answers a different question. Studies show what researchers measured. Case reports show what can happen to individual patients. Protocol descriptions show how Melanotan II is typically used. Personal accounts show what individual people experienced. Every numbered citation links to its entry below, labeled by source type.

How this guide was made

Research and drafting were AI-assisted. Cited sources were checked against their originals, and each source entry notes when only an abstract or an indexed record was available. The guide was reviewed and edited by Doserly before publication. It has not had an independent clinical review, and Doserly does not currently have medical reviewers. Doserly makes a medication and health-tracking app and runs Doserly Academy, both of which are promoted in this guide. Read our editorial policy for how guides are researched, updated and corrected.

This guide is for educational purposes. It summarizes what the reviewed sources report so the research is easier to understand; it is not medical advice. For a deeper dive, or to check any point for yourself, go straight to the cited sources.

Explore the sources