Reader’s guide · First edition · September 2026 · Revised September 23, 2026
Melanotan II
A guide to the tanning peptide: it works, no regulator has ever approved it, and the published cases are about moles, kidneys, and emergency rooms
Melanotan II is the peptide that tans. It was built at the University of Arizona in the late 1980s as a way to darken skin without sun damage, and in the handful of people who ever took it in a study it did exactly that. It was also never approved, anywhere, for anything: the same laboratory's work went on to become two prescription drugs for other conditions, and Melanotan II itself was left to the internet, where it is now sold by the vial and the nasal spray as the Barbie peptide. This guide covers what it is, what the small studies showed, the harms that have reached medical journals, how it is dosed as sold, and why an unapproved tanning injection is a different kind of risk from most of the peptides in this series.
Who this is for
Written for adults who are using, or being offered, Melanotan II for tanning, and for the parents and partners of people who are. It summarizes the published record and the regulatory position as of the edition date. It is not medical advice.
The body's own tanning signal is alpha-melanocyte-stimulating hormone, which tells pigment cells to make melanin after sun exposure. Melanotan II is a seven-amino-acid ring built to mimic it, far more potent and far longer-lasting than the original. It is also less selective: the natural hormone's receptor family controls pigment, appetite, sexual arousal, and blood pressure, and Melanotan II hits all of them. That is why the tan comes with nausea, lost appetite, and spontaneous erections, and why the same molecule was later redeveloped as a drug for sexual desire.
- Class
- Synthetic cyclic analog of alpha-MSH; a non-selective melanocortin receptor agonist
- Origin
- University of Arizona, late 1980s, as a sunless tan intended to reduce skin cancer. Pilot human studies in 1996 and 2004; never taken further as a tanning drug
- Its approved cousins
- Afamelanotide (originally Melanotan I), approved in 2019 as the Scenesse implant for a rare light-sensitivity disease; bremelanotide (PT-141), approved in 2019 as Vyleesi for low sexual desire in premenopausal women. Neither is a tanning product.
- Forms in use
- 10 mg research-chemical vials for injection; nasal sprays of unverified strength; both sold online under research labels
- Status
- Not approved anywhere. Unlawful to sell for human use in the US, UK, and Australia. Australia's regulator told consumers to stop using it in August 2026 after finding sprays with doses far off their labels.
Different from the rest of this series
Most peptides sold online have the problem of no evidence. Melanotan II has the opposite problem: it visibly does what it says, and the reasons no company ever finished developing it are the side effects. A buyer is not gambling on whether it works. They are gambling on the harms.
| Year | Study | Result | Weight |
|---|---|---|---|
| 1996 | Pilot Phase 1: three healthy men, escalating subcutaneous doses over about two weeks | Measurable darkening of the skin at the higher doses; nausea, flushing, fatigue, and spontaneous erections limited the dose | Three people |
| 2004 | Small placebo-controlled study of Melanotan II with controlled sun exposure in healthy volunteers | More tanning, and less sun damage in the tanned skin, than sun alone; the same side effects | A few dozen people over a few weeks; the last study anyone ran |
No Phase 2 or Phase 3 trial was ever run for tanning. The developer took the chemistry toward sexual dysfunction and a rare light-sensitivity disease, both of which reached approval as different molecules.
Studies longer than a few weeks, and none of the way it is used now: months of loading and maintenance, often with sunbeds
Approvals, applications, or registered trials, anywhere, as of this edition
What the evidence supports
That Melanotan II darkens skin in people, and that the darkening is real melanin rather than a stain. That is more than most peptides in this series can claim. It says nothing about safety over months, in the doses and combinations the tanning market uses, in people with many moles, or with a family history of melanoma.
Because no trial followed users for long, the safety record is a stack of case reports: people who came to a hospital and whose doctors wrote it up. Case reports cannot prove a drug caused an event. They can show what has happened to real users, and for Melanotan II the list is unusually long for a peptide.
| Event | What was reported | Plausibility |
|---|---|---|
| New and changing moles | Many reports of moles darkening, enlarging, or appearing in crops after starting; one teenager with an inherited mole syndrome whose lesions changed on the drug and sunbeds | High: the drug's job is to stimulate pigment cells, and moles are pigment cells |
| Melanoma | Several reports of melanoma diagnosed in users, some in young adults | Unproven as cause; certain as a screening problem, because darkening moles hide the changes dermatologists look for |
| Rhabdomyolysis | A 39-year-old man injected 6 mg and developed muscle breakdown with kidney injury, sympathetic overdrive, and an intensive-care stay | Dose-related; the same receptors raise blood pressure and heart rate |
| Renal infarction | A previously healthy man developed high blood pressure over six months of use and a blocked artery in one kidney | A review of the literature found the drug the likeliest cause |
| Priapism | Erections lasting hours, requiring emergency treatment, in more than one report | High: the same receptor action is the basis of the approved sexual-desire drug |
| Brain swelling syndrome | Posterior reversible encephalopathy syndrome, a blood-pressure-driven brain injury, reported in a user | Consistent with the blood-pressure effects |
| Pigment in the mouth | A 42-year-old man's gums and cheeks turned brown after two months of injections; partly reversed after stopping | Direct effect of the drug on pigment cells |
The common, non-emergency effects are near-universal: nausea and flushing after each dose, loss of appetite, fatigue, yawning, and in men spontaneous erections. Sellers call these signs that it is working.
The screening problem is the one that matters most
Melanoma is caught early by noticing a mole that changed. Melanotan II changes every mole at once. A dermatologist examining a user cannot tell a drug-darkened mole from a dangerous one without removing it, and users who started young and used sunbeds to activate the tan have added ultraviolet exposure on top. Whether the drug causes melanoma is unsettled; that it makes melanoma harder to find is not.
| Form | Instruction | What is known |
|---|---|---|
| Injection, loading | 250 to 500 mcg daily for 7 to 14 days, at bedtime to sleep through the nausea; some start at 100 mcg | The 1996 study dosed by weight over about two weeks; the loading idea comes from it |
| Injection, maintenance | 250 mcg once or twice a week to hold the tan | Custom; no study of maintenance dosing |
| With sun or sunbeds | Brief UV exposure during loading to develop the tan | The 2004 study used controlled sun; users use sunbeds, which adds a known carcinogen |
| Nasal spray | Sprays of a stated strength, several a day | Australia's regulator found labeled 30 mg bottles containing 22 to 54 mg |
What the next table is, and is not
It expresses the seller protocol for the 10 mg vial as sold, so the arithmetic can be checked and a mislabeled product recognized. Nothing in it has been tested beyond a few weeks in a few people, the drug may not lawfully be sold for human use, and a research-chemical vial's identity and strength are unverified.
- Vial
- 10 mg, as sold; identity and quantity unverified
- Water added
- 2 mL bacteriostatic water, the sellers' own instruction
- Concentration
- 5,000 mcg/mL. One concentration for the whole course.
- Syringe
- 0.3 mL insulin syringe with half-unit marks; the standard draws are 5 and 10 units
| Phase | Dose | Draw | Units | Used |
|---|---|---|---|---|
| Loading, days 1–14 | 250 mcg daily | 0.05 mL | 5 | 3.5 mg over 14 days |
| Loading, higher variant | 500 mcg daily | 0.1 mL | 10 | 7 mg over 14 days |
| Maintenance | 250 mcg twice a week | 0.05 mL | 5 | 2 mg per 4 weeks |
| The 2012 rhabdomyolysis case | 6 mg in one injection | 1.2 mL | 120 | A vial and a fifth, at once |
One vial covers loading and about three months of maintenance. The case that ended in intensive care was twelve to twenty-four times the loading dose in a single injection, which shows how little margin the arithmetic leaves for a mislabeled vial or a misread syringe.
What each draw looks like · 0.5 mL (50-unit) U-100 insulin syringe
More than one 0.5 mL syringe holds; shown full.
The plunger tip sits on the line for the dose. Units are marks on a U-100 syringe: 100 units is 1 mL. The picture assumes the concentration in the table above; a different amount of water changes every line.
- The tan needs ultraviolet light to develop. The peptide amplifies the skin's response to UV; it does not replace UV. Users who want the tan without the sun are the ones who reach for sunbeds.
- The effects outlast the dosing. Pigment changes persist for months after stopping, and the mouth pigmentation in the 2026 report had only partly faded at three months.
- Nausea is front-loaded and dose-related, which is why sellers advise bedtime dosing. It is a sign of the drug acting on receptors outside the skin, not a sign that the tan is coming.
Melanotan II sits outside every regulatory system it has touched. It has no approval, no pending application, and no place in the FDA's compounding lists, because no one has nominated it; there is no pharmacy pathway to reach for. What regulators have done is warn and, in Australia, act.
| Product | Legal position | What it is for |
|---|---|---|
| Melanotan II vial or spray | An unapproved drug everywhere; unlawful to sell for human use in the US, UK, and Australia. Sold anyway under research labels | Tanning, and the sexual side effect some buyers want |
| Scenesse (afamelanotide) | Approved implant, 2014 in Europe and 2019 in the US, placed by a physician | Reducing painful light reactions in erythropoietic protoporphyria, a rare inherited disease |
| Vyleesi (bremelanotide) | Approved injection, 2019, by prescription | Low sexual desire in premenopausal women; not a tanning drug |
| Date | Event |
|---|---|
| 1996 and 2004 | The only human studies, from the University of Arizona; development for tanning stops |
| 2007 | FDA warning letter to a Tennessee seller marketing Melanotan II as a skin cancer preventive: an unapproved new drug |
| 2009 onward | UK and Australian regulators warn the public; case reports begin to accumulate |
| 2019 | Two descendants approved for other uses: Scenesse and Vyleesi |
| Jun–Aug 2026 | The Barbie peptide trend on social media; dermatologists' warnings in the press |
| Aug 2026 | Australia's TGA tests seized nasal sprays, finds doses from 22 to 54 mg in bottles labeled 30 mg, and tells consumers to stop using Melanotan II products |
There is no lawful version
Every other title in this series has at least a prescription route, a pending listing, or an approved cousin that does the same job. Melanotan II has none. The approved descendants treat different conditions, and neither is a tanning product. A vial of Melanotan II is a research chemical with no legitimate maker, sold by people who cannot lawfully tell you how to use it.
The injection arithmetic is ordinary: micrograms from a milligram vial. The unusual part of Melanotan II is the nasal spray, which has become the popular form because it avoids needles. A spray's dose depends on the concentration in the bottle and the volume of a pump, and when a regulator measured the bottles, neither was what the label said.
units = (dose mcg ÷ concentration mcg/mL) × 100
A 10 mg vial (10,000 mcg) with 2 mL of water is 5,000 mcg/mL. A 250 mcg dose is 0.05 mL, or 5 units on a U-100 insulin syringe; 500 mcg is 10 units.
| Water added | Concentration | 250 mcg | 500 mcg |
|---|---|---|---|
| 1 mL | 10,000 mcg/mL | 2.5 units (not measurable) | 5 units |
| 2 mL | 5,000 mcg/mL | 5 units | 10 units |
| 4 mL | 2,500 mcg/mL | 10 units | 20 units |
For a nasal spray there is no arithmetic to do. The Australian test found nearly a twofold spread between bottles with the same label; a user following the instructions on the box has no way to know which one they bought.
The safety picture for Melanotan II is clearer than for most peptides in this series, and it is worse. The mechanism is understood, the side effects were documented in the first three volunteers, and the serious cases in the literature follow directly from the receptors the drug hits outside the skin.
- Near-universal
- Nausea and flushing after each dose, reduced appetite, fatigue, yawning; in men, spontaneous erections. Dose-related; worst during loading.
- Skin
- New moles, darkened and enlarged moles, darkened freckles, pigment in the nail beds and mouth. Some changes persist for months after stopping.
- Melanoma
- Reported in users; causation unproven. What is certain is that widespread mole darkening defeats the early-warning signs dermatologists rely on, and that sunbed use to develop the tan adds ultraviolet exposure.
- Cardiovascular
- Raised blood pressure and heart rate; a renal infarction and a blood-pressure brain injury in case reports; rhabdomyolysis with kidney injury after a large dose.
- Sexual
- Priapism requiring emergency treatment, in more than one report. The mechanism is the basis of an approved drug, and it does not switch off on request.
- Do not use
- With many moles, atypical moles, or a personal or family history of melanoma; with high blood pressure or heart disease; in pregnancy, where the natural hormone's receptors are active in the fetus; under 18.
- Product
- Sprays with doses far off their labels; vials of unverified identity; no sterility certification for injection.
- Unknown
- Everything past a few weeks, including the long-term fate of drug-darkened moles.
- Has a dermatologist looked at my skin, and do I know how many moles I have and what they look like now?
- Do I, or does anyone in my family, have a history of melanoma or atypical moles?
- Do I have high blood pressure or a heart condition? Am I pregnant or planning to be?
- Is this a vial or a spray, and if a spray, how could I possibly know the dose?
- Am I planning to use sunbeds to develop the tan?
- If a mole changes while I am on it, how will anyone tell whether it is the drug or something worse?
- What am I doing this for, and would a self-tanner do it?
What does have evidence
For a tan without the sun: dihydroxyacetone self-tanners, which color the outer skin layer and have decades of safe use. For protection: sunscreen and shade. For the rare disease the drug's cousin treats: Scenesse, from a physician. There is no approved way to make skin produce more melanin for cosmetic reasons, and Melanotan II is the reason regulators are not in a hurry to find one.
Latest
Developments since this edition, newest first. Items here are dated and sourced; they update the guide without re-editing it.
Australian regulator fines a seller and finds nasal sprays dosed at 22 to 54 mg
Testing of five seized bottles labeled 30 mg found 22 to 54 mg of Melanotan II each. The regulator also issued 27 infringement notices totaling A$101,412 to one New South Wales seller for unlawful supply.
FDA committee to consider Melanotan II before March 2027
Melanotan II was not voted on in July. The committee will take it up with GHK-Cu, LL-37, dihexa, and PEG-MGF at a meeting to be held before the end of February 2027.
Skin Cancer Foundation issues a formal warning against Melanotan II
The foundation said the drug is not approved for any use, cited case reports of melanoma and rapid mole changes, and advised sunless self-tanners instead of injected or nasal tanning drugs.
Dermatologists report a teenager with about 40 atypical moles after use
Australian dermatologists described new abnormal moles in Melanotan II users, including a teenager with nearly 40 atypical moles on his back. The regulator said it had asked platforms to remove 3,263 unapproved peptide ads.
References
- 1.Dorr RT, Lines R, Levine N, et al. Evaluation of melanotan-II, a superpotent cyclic melanotropic peptide in a pilot phase-I clinical study. Life Sci. 1996;58(20):1777-1784. https://pubmed.ncbi.nlm.nih.gov/8637402/
- 2.Dorr RT, et al. Effects of a superpotent melanotropic peptide with solar UV radiation on tanning in human volunteers. Arch Dermatol. 2004;140(7):827-835.
- 3.Nelson ME, Bryant SM, Aks SE. Melanotan II injection resulting in systemic toxicity and rhabdomyolysis. Clin Toxicol (Phila). 2012;50(10):1169-1173. https://pubmed.ncbi.nlm.nih.gov/23121206/
- 4.Melanotan II overdose associated with priapism. Clin Toxicol (Phila). 2013;51(4):383.
- 5.Peters B, Hadimeri H. Melanotan II: a possible cause of renal infarction: review of the literature and case report. CEN Case Rep. 2020;9(2):159-161.
- 6.Bonchev A. Changes in oral mucosa associated with Melanotan II injections: a case report. Life (Basel). 2026;16(2):265. https://pmc.ncbi.nlm.nih.gov/articles/PMC12942211/
- 7.DermNet NZ. Melanotan II: adverse effects and case reports. https://dermnetnz.org/topics/melanotan-ii
- 8.Forbes, August 7, 2026, and Axios, June 29, 2026, on the melanotan tanning trend and its risks. https://www.forbes.com/sites/brucelee/2026/08/07/tanning-influencers-push-barbie-peptide-here-are-risks-of-melanotan/
- 9.Representative Melanotan II vial and nasal-spray listings and dosing instructions from research-chemical vendors, September 2026.
- 10.U.S. Food and Drug Administration. Warning letter to Melanocorp, Inc., August 2007; approvals of Scenesse (afamelanotide) and Vyleesi (bremelanotide), 2019.
- 11.Therapeutic Goods Administration (Australia). Melanotan II tanning products found inconsistently dosed; safety alert advising consumers to stop use. August 2026. https://www.tga.gov.au/safety/safety-monitoring-and-information/safety-alerts/melanotan-ii-tanning-peptide-products-found-be-inconsistently-dosed