Melanotan II is the most-searched peptide we have not written about, and it is not close. Over the past twelve months, US searches for it have run at roughly twice the level of kisspeptin, epitalon or DSIP, peaking at the end of May as tanning season started. Social media sells it as the "Barbie drug": a few small injections or a nasal spray, a deep tan, less time in the sun. The searches that come with it are practical ones: "melanotan 2 dosage," "melanotan before and after," "melanotan side effects."
So what is it, what did the only human trials actually measure, what are the case reports that dermatologists keep citing, and why was it never approved when its sister molecule was? Let's dive in.
TLDR
What is Melanotan II? A small, ring-shaped synthetic copy of the hormone that tells your skin to make pigment (alpha-MSH). It switches on several melanocortin receptors at once: the one in pigment cells that darkens the skin, and the ones in the brain that cause erections, nausea and loss of appetite.
Results: It does darken skin. In the one published tanning study, 2 of 3 men had visibly more pigment after five low doses. The other two trials were for erectile dysfunction, in 10 men each. That is the entire controlled human record: about 23 people, all in the 1990s, none followed for longer than a few weeks.
Dosage: The trials used 0.01 to 0.03 mg per kg of body weight, about 0.75 to 2.25 mg for a 75 kg man. Online protocols start at 250 mcg a day and work up to 1 mg. No protocol has ever been tested for safety or for tanning dose.
Safety: Nausea, flushing, yawning and unplanned erections are the expected effects. On the serious side, the case reports include melanomas arising in moles that darkened quickly, moles appearing in crops, priapism needing surgery, a muscle-breakdown emergency and a brain-swelling syndrome. None of these proves cause. All of them are why the FDA names it as a safety risk.
Legal Status (October 2026): Not approved for any use, in the US or anywhere else. On the FDA's list of peptides that may present significant safety risks in compounding, so pharmacies cannot make it. Research-labelled vials are unapproved drugs in the FDA's view. Banned in sport under WADA's S0 category for unapproved substances.
What Is Melanotan II, and Why Is Everyone Searching for It Now?
Melanotan II came out of the University of Arizona in the late 1980s and early 1990s. The idea was a good one: a sunless tan that protects against sunburn and, in theory, skin cancer. Researchers took alpha-melanocyte-stimulating hormone, the body's own signal for making melanin, and built two longer-lasting versions of it (Hadley and Dorr, 2006, Peptides, PMID 16412534).
Melanotan I was the straight-chain version. It became afamelanotide, a slow-release implant sold as Scenesse, and the FDA approved it in October 2019 for erythropoietic protoporphyria, a rare genetic disorder where sunlight causes severe pain (Langendonk et al., 2015, NEJM, PMID 26132941).
Melanotan II was the ring-shaped version: smaller, more potent, and much less selective. In its first human study, the surprise was spontaneous erections. That side effect turned into a drug of its own, bremelanotide (PT-141), which we covered in our PT-141 guide. Melanotan II itself never went further than small pilot trials.
Its revival is entirely online. UK doctors were already warning about internet sales in 2009 (Evans-Brown et al., 2009, BMJ, PMID 19224885). The current wave has three parts landing together: "tan in a week" social media content, nasal sprays that remove the needle from the pitch, and research-peptide sellers listing it next to BPC-157 and retatrutide. Then the warnings arrived. On July 7, 2026, the Skin Cancer Foundation issued a statement strongly discouraging its use, citing melanoma case reports and rapid mole changes. On July 23, a Mississippi dermatologist's warning about the "Barbie drug" was syndicated across Gray TV stations nationwide. And in May a US case report described five separate melanomas in one man who had used it for a few weeks (Vadner and Smith, 2026, JAAD Case Reports, PMID 42328529).
Melanotan II is not an experimental drug waiting for approval. It is a 30-year-old research compound whose development stopped, sold today on the strength of social media.
How Does Melanotan II Work?
Your skin's pigment cells, melanocytes, carry the melanocortin-1 receptor (MC1R). When alpha-MSH binds it, they switch from making little light-coloured pigment to making more dark eumelanin. That is the tan, and it is also part of how the skin protects itself after sun damage.
Melanotan II binds MC1R strongly. The problem is that it also binds MC3R, MC4R and MC5R, the other receptors in the same family (Vadner and Smith, 2026, JAAD Case Reports, PMID 42328529). MC4R in the brain is the one behind its other effects. It controls appetite and is part of the circuit for sexual arousal, which is why the trials saw erections, stretching and yawning, nausea and lower appetite.
Here's the caveat that matters for skin cancer. MC1R is not only on the even background of your skin. It is on the melanocytes inside every mole you have. Turn them all up at once, and moles darken, sometimes within a day, and new ones can appear (Schulze et al., 2014, European Journal of Dermatology, PMID 24334249). Whether that pushes a mole toward cancer is unproven. What it certainly does is change what your moles look like, which is the main way a dermatologist spots melanoma early.
Melanotan II is not a skin-only drug. It is a whole-family melanocortin agonist, and the tan is only one of the things it switches on.
Melanotan II vs Melanotan I vs PT-141 vs the Alternatives
| Option | How it works | Approved? | How it is used | The catch |
|---|---|---|---|---|
| Melanotan II | Agonist at MC1R, MC3R, MC4R and MC5R | No, anywhere | Gray-market injection or nasal spray | Nausea, erections, mole changes; melanoma, priapism and toxicity case reports |
| Afamelanotide (Melanotan I, Scenesse) | Mostly MC1R | Yes, 2019, for EPP only | 16 mg implant every 2 months, inserted by a trained clinician | Not for cosmetic tanning; label recommends a full-body skin exam twice a year |
| Bremelanotide (PT-141, Vyleesi) | MC4R in the brain, weaker on pigment | Yes, 2019, for low desire in premenopausal women | 1.75 mg injection, as needed | Nausea in 40%; darkened skin patches in about 1% |
| Sunless tanner (DHA) | Stains the outer dead layer of skin | DHA is FDA-approved as a color additive for external use | Lotion, mousse or booth spray | Fades in about a week; gives no sun protection |
| Sunbed / sun | UV damages DNA; the skin responds with pigment | Sunbeds are regulated, not "approved" | Repeated exposure | The tan is itself a sign of DNA damage; a proven melanoma risk |
The detail that gets dropped in almost every comparison: most Melanotan II users still use sunbeds or the sun. Two of the melanoma case reports below involve sunbeds alongside the injections. The peptide is sold as a way to skip the UV, and in practice it is often stacked on top of it.
What the Evidence Actually Shows
The useful split here is not "published vs unpublished," because there is no company and no pipeline. It is between the handful of controlled trials and the much longer list of case reports and lab tests that came after Melanotan II went onto the internet.
The controlled human trials
| Study | Who | Dose | What it found | Status |
|---|---|---|---|---|
| Dorr et al., 1996, Life Sciences | 3 healthy men | 0.01 rising to 0.025 to 0.03 mg/kg, 5 doses every other day | More pigment in face, upper body and buttocks in 2 of 3; mild nausea; erections for 1 to 5 hours after doses; grade II drowsiness and fatigue at 0.03 mg/kg | Published pilot, Phase 1 |
| Wessells et al., 1998, Journal of Urology | 10 men, psychogenic erectile dysfunction | 0.025 mg/kg, single injections, crossover with placebo | Erections in 8 of 10; 38 minutes of strong rigidity vs 3 on placebo | Published, double-blind |
| Wessells et al., 2000, Urology | 10 men, erectile dysfunction with physical causes | 0.025 mg/kg, two injections each | Erections after 12 of 19 injections vs 1 of 21 placebo; higher desire; severe nausea after 4 of 19 injections | Published, double-blind |
| Any tanning efficacy trial | None | None | No study has measured how much tan, how fast, at what dose, or for how long | Never run |
| Any long-term safety study | None | None | The longest controlled exposure is two weeks | Never run |
That is it. Roughly 23 people across three small studies, the largest with ten. The tanning claim rests on two men in a 1996 pilot (Dorr et al., 1996, Life Sciences, PMID 8637402; Wessells et al., 1998, Journal of Urology, PMID 9679884; Wessells et al., 2000, Urology, PMID 11018622).
The case reports and lab findings
| Report | What happened | What it shows |
|---|---|---|
| Cousen et al., 2009; Schulze et al., 2014 | Crops of new moles; darkening of existing moles 24 hours after a single dose | The mole effect is fast and visible |
| Paurobally et al., 2011; Ong et al., 2012; Hjuler and Lorentzen, 2014 | Melanomas, including melanoma in situ, in users; one in a 20-year-old woman three months after a 3 to 4 week course plus sunbeds | Melanoma has been found repeatedly in users |
| Yassin Alsabbagh et al., 2025 | Mucosal melanoma in the mouth of a 22-year-old woman who used the nasal spray | The spray route has its own case report |
| Vadner and Smith, 2026 | A 49-year-old man; daily 250, 500, then 1,000 mcg, plus 12 sunbed sessions; moles "turned black" within a week; five melanomas in situ on biopsy | The most recent US case, with sunbeds and unregulated testosterone as co-exposures |
| Nelson et al., 2012 | 6 mg injected at once; racing heart, tremor, kidney injury; muscle enzyme (CK) peaked at 17,773; three days in intensive care | Overdose produces a stimulant-like toxicity with muscle breakdown |
| Devlin et al., 2013; Dreyer et al., 2019; Mallory et al., 2021 | Priapism; in one case erections had not returned at four weeks, in another surgery was needed | The sexual effect can become an emergency |
| Kaski et al., 2013; Peters et al., 2020 | Posterior reversible encephalopathy syndrome (brain swelling); a kidney infarction | Rare vascular events, cause uncertain |
| Breindahl et al., 2015 | Vials from three online shops, each sold as 10 mg, held 4.32 to 8.84 mg; two shops had 4 to 6% unknown impurities | The label dose is not the real dose |
A 2017 dermatology review counted four case reports by then of melanomas arising from existing moles during or shortly after use, and was careful to say conclusive evidence linking the two is lacking (Habbema et al., 2017, International Journal of Dermatology, PMID 28266027).
The melanoma signal is real and repeated. Proof that Melanotan II causes melanoma does not exist. Those are two separate facts, and the honest position holds both.
Here's why the case reports can't settle it. The people who use a tanning injection are, almost by definition, people who tan. Many are fair-skinned, many use sunbeds, and most of the reports involve exactly that mix. Untangling the peptide from the UV would take a proper study, and nobody is going to run one on an unapproved cosmetic drug.
Melanotan II Dosage: Trials vs Community Reports
Let's be clear first: there is no validated Melanotan II protocol. Nobody has studied what dose produces what tan, and nobody has studied repeated cycles. Everything below is either what three 1990s trials used, or what people report online.
What the trials used
The trials dosed by body weight: 0.01 mg/kg to start, with 0.025 mg/kg settled on as the recommended single dose after one of two men had marked drowsiness and fatigue at 0.03 mg/kg (Dorr et al., 1996, Life Sciences, PMID 8637402). For a 75 kg adult, 0.025 mg/kg is about 1.9 mg. Even at that dose, nausea was common, and severe after about one injection in five in the 2000 trial.
What the community reports
Online protocols typically start much lower, at 100 to 250 mcg a day, rising over one to two weeks to 500 mcg or 1 mg until the user is happy with the colour, then dropping to one or two "maintenance" doses a week. The 2026 case report describes exactly this pattern: 250 mcg, then 500 mcg, then 1,000 mcg daily, about three days at each step (Vadner and Smith, 2026, JAAD Case Reports, PMID 42328529). None of those numbers come from a trial.
Nasal sprays are even less predictable. How much peptide crosses the nasal lining has never been measured, and when Australia's regulator tested one spray brand, identically labelled bottles held very different amounts. We could not confirm that test against the regulator's own notice, so treat it as reported, not verified.
The reconstitution arithmetic
Most vials are sold as 10 mg of powder. With 2 mL of bacteriostatic water, that is 5 mg/mL, or 50 mcg per unit on a U-100 insulin syringe. Work your own numbers with the reconstitution calculator and the dosage calculator.
| Dose | Units at 2 mL (5 mg/mL) | Units at 1 mL (10 mg/mL) | Doses per 10 mg vial |
|---|---|---|---|
| 100 mcg | 2 | 1 | 100 |
| 250 mcg | 5 | 2.5 | 40 |
| 500 mcg | 10 | 5 | 20 |
| 1 mg | 20 | 10 | 10 |
| 1.9 mg (trial dose, 75 kg) | 38 | 19 | About 5 |
Here's the caveat the dosing charts never print. In the one published lab test of online vials, a "10 mg" vial held between 4.32 and 8.84 mg (Breindahl et al., 2015, Drug Testing and Analysis, PMID 24771717). Mix a 4.32 mg vial with 2 mL and your "250 mcg" at 5 units is really about 108 mcg. Switch to a fuller vial from the next batch and the same 5 units more than doubles. The arithmetic is only as good as the powder.
The math on the syringe is exact. The amount in the vial is not, and with this peptide the gap between the two is measured in multiples.
Melanotan II Side Effects
The expected ones
Nausea. The most consistent effect in every trial, usually in the first hours after a dose, and severe in some. It is the reason most protocols start low.
Facial flushing. Common, short-lived.
Stretching and yawning. An odd but well-documented MC4R effect. In the first trial it came just before the erections.
Spontaneous erections. In men, lasting 1 to 5 hours after a dose in the pilot.
Lower appetite. Reported in the 1998 trial. Some people now use it partly for this.
Freckles and moles getting darker. Not a side effect so much as the drug working on every melanocyte, not just the even ones. There is no good evidence on how fully it fades afterwards.
Injection-site problems. Including abscesses, which a dermatologist interviewed in July said have been reported, a sign of non-sterile product or technique.
When to stop and get seen
Stop and see a doctor if you notice any of these:
- A mole that changes shape, grows, bleeds, itches or turns very dark quickly
- A crop of new moles
- An erection lasting more than four hours (this is an emergency)
- Racing heart, tremor, heavy sweating or agitation after a dose
- Dark urine or severe muscle pain
- Sudden severe headache, confusion or changes in vision
If you have used it, tell your dermatologist, and get a full skin check. Darkened moles can hide the changes they look for.
Who should not use it
Anyone with a personal or family history of melanoma. The whole melanoma concern lands hardest here.
Fair skin with many moles. Both of the detailed melanoma reports above were in people with Fitzpatrick type II skin, and the most recent patient had a high mole count.
Heart disease or high blood pressure. Its sister drug bremelanotide raises blood pressure after every dose and is contraindicated in uncontrolled hypertension.
Pregnancy and breastfeeding. No safety data at all.
Is Melanotan II Legal?
Short answer: it is not approved anywhere, and in the US it cannot legally be sold as a drug.
FDA approval. Melanotan II has never been approved by the FDA for any use, and no company is developing it. Its two relatives are approved: afamelanotide for EPP and bremelanotide for low desire in women. Neither approval extends to Melanotan II.
Compounding. Melanotan II sits on the FDA's list of bulk substances that may present significant safety risks in compounding. The FDA's entry cites possible immune reactions from peptide impurities and case reports of melanoma, brain swelling, stimulant-like toxicity and priapism. It is listed among the substances whose nominations were withdrawn, and it has not yet been before the Pharmacy Compounding Advisory Committee. The April 2026 Federal Register notice said a second meeting would come before the end of February 2027, which is the earliest any change could start. See our explainer on the FDA's temporary sale plan for which peptides that covers.
Research-use vials. "For research use only" labels do not make a product legal to sell for injecting into people. The FDA treats vials marketed that way as unapproved new drugs, and the Paradigm Peptides prosecution showed how far that can go (read the case).
Sport. It is not named individually on the WADA Prohibited List, but WADA's S0 category bans any substance not approved for human therapeutic use, which covers it at all times.
Outside the US. Melanotan II is unlicensed in the UK, the EU and Australia too, and health agencies in several countries have issued warnings about it (Habbema et al., 2017, International Journal of Dermatology, PMID 28266027).
The Honest Take
Melanotan II works. That is not in dispute: it darkens skin, and it does it quickly. The question is what else it does, and the honest answer is that nobody knows, because the controlled human record is about 23 people for two weeks in the 1990s.
What we do have is more than 15 years of case reports that keep pointing in the same direction. Moles darken within a day. New moles appear. Melanomas turn up in users, the most recent one five at once. Case reports can't prove cause, and the sunbed problem makes the evidence genuinely messy. But the signal is consistent, the mechanism is plausible, and the people most drawn to the drug, fair-skinned and sun-seeking, are exactly the people who can least afford to be wrong about it.
Then there is the product. A drug dosed in micrograms, sold in vials that held as little as 43% of the label in the one published test, is not something you can dose precisely no matter how carefully you do the math.
If you want colour without UV, a DHA self-tanner does that with a well-understood safety record. If you have already used Melanotan II, the useful step is a full-body skin check, and telling the dermatologist what you used.
The melanoma risk is unproven. The mole changes are not. And a tan that hides changes in your moles is a bad trade for anyone with something to hide.
FAQ
What is Melanotan II?
A synthetic, ring-shaped version of alpha-MSH, the hormone that triggers skin pigment. It was developed at the University of Arizona in the early 1990s as a sunless tanning agent and never approved.
What is the difference between Melanotan 1 and Melanotan 2?
Melanotan I mostly targets the pigment receptor and became the approved drug afamelanotide (Scenesse). Melanotan II hits several melanocortin receptors, which is why it also causes erections, nausea and appetite loss. Only Melanotan I was ever developed into a medicine.
Is Melanotan II the same as PT-141?
No, but they are close relatives. Bremelanotide (PT-141) is Melanotan II with one small change at the end of the chain, which keeps most of the sexual effect and loses most of the tanning. PT-141 is FDA-approved as Vyleesi; Melanotan II is not.
Does Melanotan II cause skin cancer?
It has not been proven to. But there are repeated case reports of melanoma in users, often in moles that darkened quickly, and the FDA lists melanoma among its safety concerns. Most cases also involved sunbeds or heavy sun exposure, which makes cause hard to separate.
What is the Melanotan 2 dosage?
There is no validated dose. Trials used 0.01 to 0.03 mg/kg, about 0.75 to 2.25 mg for a 75 kg adult. Online protocols start at 100 to 250 mcg a day and build up to 1 mg, then drop to weekly maintenance. None of these have been tested for safety.
How long does it take to see results?
In the 1996 pilot, increased pigment was measurable a week after five doses. Users commonly report visible colour within one to two weeks, often with sun or sunbed exposure added, but no study has measured this.
Does Melanotan II work without sun?
Partly. The pilot study showed more pigment without deliberate UV exposure. Most users still add sun or sunbeds, which defeats the original point of a UV-free tan and adds the UV risk back.
How long does a Melanotan tan last?
There are no data. Users report fading over weeks to months without maintenance doses. Darkened moles and freckles may not fully fade.
Is the Melanotan nasal spray safer than injections?
There is no evidence it is. Absorption through the nose has never been measured, so the dose is even less predictable, and one 2025 case report described melanoma in the mouth of a young woman who used a spray.
Why does Melanotan II make you nauseous?
It acts on melanocortin receptors in the brain, the same system that controls appetite and nausea. Nausea was the most common side effect in every trial, and severe after about one in five injections in one of them.
Is Melanotan II legal in the US?
It is not approved, pharmacies cannot compound it, and vials sold "for research use only" are unapproved drugs in the FDA's view. Buying it for personal use is a legal gray area; selling it for human use is not.
Should I see a dermatologist if I have used Melanotan II?
Yes. Get a full-body skin check, mention the peptide, and go sooner if any mole changes quickly, bleeds or itches. Even the approved relative, afamelanotide, carries a label recommendation for skin exams twice a year.
Resources
Dorr et al. (1996), Life Sciences, pilot Phase 1 study of Melanotan II in three men — https://pubmed.ncbi.nlm.nih.gov/8637402/
Wessells et al. (1998), Journal of Urology, Melanotan II in psychogenic erectile dysfunction — https://pubmed.ncbi.nlm.nih.gov/9679884/
Wessells et al. (2000), Urology, Melanotan II in organic erectile dysfunction — https://pubmed.ncbi.nlm.nih.gov/11018622/
Hadley and Dorr (2006), Peptides, history of the melanocortin peptide programme — https://pubmed.ncbi.nlm.nih.gov/16412534/
Langendonk et al. (2015), New England Journal of Medicine, afamelanotide for erythropoietic protoporphyria — https://pubmed.ncbi.nlm.nih.gov/26132941/
Evans-Brown et al. (2009), BMJ, use of melanotan I and II in the general population — https://pubmed.ncbi.nlm.nih.gov/19224885/
Cousen et al. (2009), British Journal of Dermatology, eruptive moles after melanotan — https://pubmed.ncbi.nlm.nih.gov/19575725/
Paurobally et al. (2011), British Journal of Dermatology, melanotan-associated melanoma — https://pubmed.ncbi.nlm.nih.gov/21564053/
Ong et al. (2012), Australasian Journal of Dermatology, melanotan-associated melanoma in situ — https://pubmed.ncbi.nlm.nih.gov/22724573/
Nelson et al. (2012), Clinical Toxicology, systemic toxicity and rhabdomyolysis after Melanotan II — https://pubmed.ncbi.nlm.nih.gov/23121206/
Devlin et al. (2013), Clinical Toxicology, Melanotan II overdose with priapism — https://pubmed.ncbi.nlm.nih.gov/23537392/
Kaski et al. (2013), Annals of Internal Medicine, melanotan and posterior reversible encephalopathy syndrome — https://pubmed.ncbi.nlm.nih.gov/23648958/
Schulze et al. (2014), European Journal of Dermatology, mole changes 24 hours after one dose — https://pubmed.ncbi.nlm.nih.gov/24334249/
Hjuler and Lorentzen (2014), Dermatology, melanoma after Melanotan II and sunbeds — https://pubmed.ncbi.nlm.nih.gov/24355990/
Breindahl et al. (2015), Drug Testing and Analysis, content and purity of online Melanotan II vials — https://pubmed.ncbi.nlm.nih.gov/24771717/
Habbema et al. (2017), International Journal of Dermatology, review of the risks of unregulated melanotan use — https://pubmed.ncbi.nlm.nih.gov/28266027/
Dreyer et al. (2019), BMJ Case Reports, melanotan-induced priapism — https://pubmed.ncbi.nlm.nih.gov/30796078/
Peters et al. (2020), CEN Case Reports, possible renal infarction from Melanotan II — https://pubmed.ncbi.nlm.nih.gov/31953620/
Mallory et al. (2021), Sexual Medicine, priapism needing surgical decompression — https://pubmed.ncbi.nlm.nih.gov/33460908/
Yassin Alsabbagh et al. (2025), International Journal of Oral and Maxillofacial Surgery, oral melanoma after nasal spray — https://pubmed.ncbi.nlm.nih.gov/40210573/
Vadner and Smith (2026), JAAD Case Reports, five melanomas in situ after melanotan and sunbeds — https://pmc.ncbi.nlm.nih.gov/articles/PMC13279914/
Clinuvel (2026), Scenesse (afamelanotide) prescribing information, DailyMed — https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=94f53286-11dd-7fbb-e053-2a95a90a7c48
Cosette Pharmaceuticals (2025), Vyleesi (bremelanotide) prescribing information, DailyMed — https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=f1d0c1b5-2f39-4bad-a6a4-0066e3ad5dcf
FDA (2026), bulk drug substances that may present significant safety risks in compounding, Melanotan II entry — https://www.fda.gov/drugs/human-drug-compounding/certain-bulk-drug-substances-use-compounding-may-present-significant-safety-risks
Federal Register (2026), Pharmacy Compounding Advisory Committee notice, April 16 — https://www.federalregister.gov/documents/2026/04/16/2026-07361/pharmacy-compounding-advisory-committee-notice-of-meeting-establishment-of-a-public-docket-request
The Skin Cancer Foundation (2026), warning regarding Melanotan II, July 7 — https://www.skincancer.org/press/the-skin-cancer-foundation-issues-warning-regarding-melanotan-ii/
WDAM / Gray News (2026), dermatologist warns about the "Barbie drug," July 23 — https://www.wfsb.com/2026/07/23/dermatologist-warns-about-using-barbie-drug-tanning/
WADA (2026), Prohibited List — https://www.wada-ama.org/en/resources/2026-prohibited-list
ONPEPS, PT-141 library entry — https://www.onpeps.com/peptides/pt-141
