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Melanotan II 10 mg
Peptide Library · Profile
Melanotan II 10 mg
Melanotan II is bought for tanning. There has never been a controlled human trial of Melanotan II for tanning. The tanning studies everyone cites used Melanotan I — a different molecule, twice the size, now an approved medicine. What Melanotan II actually has proper randomised evidence for is erections.
Molecular weight1,024.2Da · free base · CAS 121062-08-6
Controlled tanning trialsNonethe tanning data is Melanotan I
Vials tested against label4.3 to 8.8 mgin vials sold as 10 mg
Approved anywhereNowhich is why WADA's S0 catches it
The short version
Plain English first. Everything below this section is the same material with the sources, the numbers and the caveats attached.
What it is
A melanocortin peptide, bought almost entirely for tanning.
What has actually been measured
Erections. That is what Melanotan II has proper randomised human evidence for — not what it is bought for.
What has not been measured
Tanning. There has never been a controlled human trial of Melanotan II for tanning. The tanning studies everyone cites used Melanotan I — a different molecule, twice the size, and now an approved medicine.
What most people get wrong
What is actually in the vial. When vials sold as 10 mg were tested, they held between 4.3 and 8.8 mg.
What Melanotan II is
A cyclic ring of seven amino acids, closed by a lactam bridge, from the same University of Arizona programme that produced two other melanocortin drugs. Understanding which is which is most of the work on this page, because the three get confused constantly — including by the pages selling them.
| Melanotan II | PT-141 | Melanotan I | |
|---|---|---|---|
| Backbone | cyclic 7-mer | the same | linear 13-mer |
| C-terminus | …Lys-NH2 | …Lys-OH | — |
| Formula | C50H69N15O9 | C50H68N14O10 | C78H111N21O19 |
| Weight | 1,024.2 Da | 1,025.2 Da | 1,646.9 Da |
| Approved? | Nowhere | Yes — Vyleesi | Yes — Scenesse |
So the sibling everyone names it with — "Melanotan I and II" — is not its close relative. Melanotan I is a different backbone, a different length and 60% heavier. The molecule Melanotan II actually resembles is PT-141, which differs by a single functional group: an amide where PT-141 has an acid.
Bremelanotide is often described as a metabolite of Melanotan II. The structural relationship is certain; the metabolite claim we could not trace to a primary source, so we report it as asserted.
What a "10 mg" vial holds, twice over
First, the salt. Working the masses through, a nominal 10 mg vial is 8.2 to 9.5 mg of peptide depending on counterion — our arithmetic, and an overestimate at that, since vials also hold residual water. Cayman Chemical's own datasheet for the acetate prints the free base weight beside an acetate formula, so even an analytical supplier does not always get this right.
Second, and worse: somebody opened the vials. See the reconstitution section. Two independent regulator-grade analyses found the milligram figure on the label was wrong — in one case badly low, in the other badly high.
How it works
Melanotan II is a non-selective agonist at four melanocortin receptors — MC1, MC3, MC4 and MC5. That single word explains nearly everything about how it behaves, including the parts nobody wants.
The best citation for it is a paper whose entire purpose was to engineer the problem away. Doedens and colleagues, 2010, describe Melanotan II as "a superpotent but nonselective cyclic peptide" with activity "at all subtypes… without preferential selectivity."
| Receptor | What it does |
|---|---|
| MC1R | melanin production — the tan, and the moles |
| MC3R / MC4R | erection, appetite suppression, central metabolic effects |
| MC5R | exocrine gland function |
There is no dose at which MC1R is engaged and MC4R is not. The nausea, the flushing, the yawning and stretching, the appetite loss and the spontaneous erections are not side effects in any avoidable sense. They are the same drug doing the same thing at receptors you were not aiming for. A lower dose gives you less of everything, not less of the unwanted parts.
One thing we could not get: actual affinity numbers. The reference database that holds Melanotan II's per-receptor potency sits behind a login, and no open source we found published Ki or EC50 figures at the human receptors. Non-selectivity is well sourced; the numbers we will not invent.
The approved relative is not simply "more selective"
You will read that afamelanotide — Melanotan I, the approved one — is safe because it is MC1R-selective. Its own FDA label calls it an "MC1-R agonist", which is a statement of mechanism, not of selectivity, and in functional assays the same molecule is potent at MC3, MC4 and MC5 too.
Its safety record comes from somewhere less flattering to Melanotan II: it is a two-monthly implant, placed by a trained clinician, at a fixed dose, in patients under dermatological surveillance. The delivery and the supervision are doing the work.
Pharmacokinetics
There is no published human pharmacokinetic study of Melanotan II. None. We looked specifically for measured plasma concentrations and found nothing.
Two half-life figures circulate, and they disagree by a factor of thirty-four.
| Claim | What is behind it |
|---|---|
| "34 hours" | Asserted to be "the published estimate… from pharmacokinetic studies" — with no study, paper or link given. The chain ends at that sentence. |
| "About 1 hour" | Cites a PMID we could not resolve to any Melanotan II paper; searches for it surface bremelanotide literature instead. |
For scale, both close relatives are short-lived. PT-141, the same backbone, has a measured half-life of 2.7 hours from its approved label. Melanotan I's terminal half-life is 0.8 to 1.7 hours. That makes a 34-hour claim for Melanotan II implausible on its face — but implausible is not measured, and we are not going to pretend otherwise.
There is also no human data at all on nasal absorption, despite nasal sprays being widely sold — and being the form that Australia's regulator seized and tested in August 2026.
What the evidence shows
This is the section that should change what you think about this compound. The controlled human evidence for Melanotan II is real, and it is for something other than tanning.
The inventors split the two molecules by purpose, and said so
Hadley and Dorr's own retrospective states the two analogues were "tested clinically for studies on tanning of the skin (MTI) and for diagnosis and treatment of male erectile dysfunction (MTII)." Every substantial human tanning trial we could find used Melanotan I. The famous "tan with less sun" work — 47% fewer sunburn cells, 50% more sun needed to match controls — is Melanotan I, at 0.08 to 0.16 mg/kg a day.
What exists for Melanotan II
| Study | n | Design | Measuring |
|---|---|---|---|
| Dorr 1996 | 3 | Uncontrolled pilot | Tanning. The only one. |
| Wessells 1998 | 10 | Double-blind, placebo, crossover | Erections |
| Wessells 2000 | 10 | Double-blind, placebo, crossover | Erections |
| Wessells 2000b | 20 | Double-blind, placebo, crossover | Erections |
The erection trials are genuinely good small trials. At 0.025 mg/kg subcutaneously — about 1.75 to 2 mg for an adult — 17 of 20 men had erections without sexual stimulation, tip rigidity above 80% for around 41 minutes against 3 minutes on placebo. Sexual motivation rose after 68% of doses against 19% on placebo. Severe nausea in 12.9%.
Every one of those was a single dose under observation over six hours. None ran longer. None measured tanning.
So the evidence and the marketing point in different directions. The compound has randomised, double-blind, placebo-controlled human data — for erectile function, at a single dose, in twenty men, in the late 1990s. For the thing it is actually sold for, the entire human record is three people in an uncontrolled pilot whose abstract we could not even open.
That is why this page is graded "limited human data" rather than "preclinical only". Real trials exist. They are not about tanning.
One trial is running now, and it is worth knowing about
A phase 2 study of Melanotan II with narrowband UVB for repigmentation in stable vitiligo is currently enrolling — randomised, quadruple-blind, placebo-controlled, 60 patients, 24 weeks. Note what it is: a repigmentation indication, under supervision, in patients screened to exclude any history of melanoma.
Reconstitution
Start with the uncomfortable part: on this compound, two separate regulator-grade analyses have found the number on the label to be wrong.
Somebody opened the vials
Breindahl and colleagues, 2015. Injectable Melanotan II bought from three internet retailers, analysed by liquid chromatography and mass spectrometry. Vials sold as 10 mg contained 4.32 to 8.84 mg. Unidentified impurities of 4.1 to 5.9% in two of the three.
Australia's TGA, August 2026. Five nasal sprays labelled 30 mg tested. They contained 22 to 54 mg — the regulator noting the "variation in dosage across the products increasing the risk of adverse events." Twenty-seven infringement notices followed, totalling A$101,412.
One study found roughly half the stated dose; the other found nearly double. Both were looking at product sold the same way. A microgram figure in any protocol is nominal at best, and two vials with identical labels can differ by a factor of two.
This is the clearest argument in the whole library for buying against a lot-specific certificate rather than a printed milligram figure. Ours are on the certificate register.
If you are reconstituting
Against the 250 to 1000 mcg figures that circulate:
| Bacteriostatic water | Concentration | 1 unit (U-100) = | 500 mcg draw |
|---|---|---|---|
| 2 mL | 5 mg/mL | 50 mcg | 10 units · 0.10 mL |
| 3 mL | 3.33 mg/mL | 33.3 mcg | 15 units · 0.15 mL |
| 5 mL | 2 mg/mL | 20 mcg | 25 units · 0.25 mL |
A conflict worth naming rather than hiding: Cayman's insert for the analytical standard says aqueous solutions should not be kept beyond one day, which is far stricter than the 28 days our storage guide gives for bacteriostatic water. Those are different articles — an unpreserved analytical solution against a preserved reconstitution — but nobody has published stability data for the second, so the 28 days is convention rather than measurement here.
Reported protocols
The circulating protocol is a loading phase and then maintenance: 100 to 250 mcg daily for three days, 250 to 500 mcg to two weeks, 500 to 1000 mcg daily thereafter, then weekly top-ups. We traced where those numbers come from. The chain breaks in a specific and instructive place.
To its credit, the most detailed dosing page states outright that "there is no FDA-approved dose for Melanotan 2" and that its schedules are "built from early human studies and community use." It then cites three papers. Two of the three do not support the protocol, and one is a different molecule.
| Cited | What it actually is |
|---|---|
| Dorr 2004 | A Melanotan I study. 0.08 to 0.16 mg/kg a day — 5.6 to 12.8 mg for an adult, an order of magnitude above the microgram ladder it is cited to support. |
| Wessells 1998 / 2000 | 0.025 mg/kg as a single observed dose in a six-hour erection study. Not a daily schedule. |
| Dorr 1996 | The only genuine Melanotan II tanning study. Three people, uncontrolled. We could not obtain its doses. |
The loading ladder, the maintenance architecture and "inject until you reach the tan you want" appear in no study we could find. They are community convention, fitted afterwards with citations that do not match — one of them to a different compound.
Two real exposures, from published case reports
Both sit comfortably inside what is described online as normal:
- 400 mcg every other day for 64 days — 32 injections, 12.8 mg cumulative. Produced pigmentation of the gums and inner cheeks. The cheek pigmentation nearly cleared in 28 days; the gum pigmentation was still there at three months.
- 27 mg over six months — coincided with a renal infarction affecting about half of one kidney in a previously healthy 45-year-old. See the safety section.
Storage
Lyophilised, sealed, cold, dark and dry. Our storage guide covers the general conventions.
Cayman's insert for the acetate gives −20 °C, stable four years or more as supplied. Solubility on the same document: about 30 mg/mL in DMF, 15 in DMSO, 1 in ethanol, and only 0.20 mg/mL in aqueous buffer. Other catalogues give water figures of 0.70 and 5 mg/mL. These disagree, none publishes a method, and Cayman's is the better-evidenced of them because it is a manufacturer's QC document for a defined salt at a stated purity.
Do not freeze a reconstituted solution and do not shake it. And note the honest tension flagged in reconstitution: the analytical standard's insert says one day in water, while the convention for a preserved reconstitution is 28 days. Nobody has published stability data that bridges the two for this compound.
Reported effects
The common effects are predictable from the pharmacology. The serious ones are documented in case reports rather than trials — which limits what can be concluded, and does not make them less real.
Routinely reported: nausea, sometimes severe; vomiting; facial flushing; stretching and yawning; appetite suppression; fatigue; spontaneous erections; darkening of moles and freckles; darkening of the nails; general skin darkening within about five doses.
Moles, and why this is the section that matters
A 2019 review collated ten Melanotan-associated cases of eruptive melanocytic naevi. The pattern across them:
| Finding | Frequency |
|---|---|
| Onset within days or weeks | 6 of 8 |
| Existing moles darkened | 8 of 10 |
| Biopsy-confirmed dysplasia | 4 of 10 |
| Melanoma developed | 2 of 10, both in pre-existing moles |
One case is worth stating in full because of its timescale: eruptive naevi and darkening of existing moles 24 hours after a single dose. Another: a 25-year-old man developed more than a hundred new moles over four weeks; ten of the most atypical were biopsied and all ten were dysplastic, three severely.
What can and cannot be concluded
These are case reports. Nobody has run a cohort study or a case-control study, so causation of melanoma is not established, and the confounding is heavy — several of the patients were using sunbeds at the same time.
But you do not need the causation claim to reach the important conclusion. What is established is that Melanotan II reliably darkens and multiplies moles within days, makes existing lesions change quickly, and produces new lesions that are frequently dysplastic on biopsy. That degrades the exact visual signal dermatologists rely on to catch melanoma early. Rapid change in a mole is the warning sign; this compound makes rapid change the baseline.
The approved melanocortin drug carries a version of this warning too. Scenesse's label notes it "may cause darkening of pre-existing nevi and ephelides" and recommends a full-body skin examination twice a year. If the regulated, supervised, fixed-dose implant needs six-monthly dermatological surveillance, the unregulated non-selective one at an unknown dose needs at least as much.
The serious case reports
| Event | What was reported |
|---|---|
| Renal infarction | 45-year-old man, previously healthy, 27 mg over six months. Infarction of about half of one kidney; renal arteries normal, embolic sources excluded. Authors hedge causation appropriately and note no drug level was measured. |
| Priapism | At least four separate published case reports. No denominator exists, so incidence is unknown — and a 2026 review of drug-induced priapism does not mention melanotan at all. Both halves of that are true. |
| Rhabdomyolysis | A 2012 case report exists and drew a published letter disputing it. We could not open the abstract, so we have no dose, no lab values and no outcome. |
| Encephalopathy (PRES) | A 2013 case report in Annals of Internal Medicine. We could not open it either. We report that it exists. |
| Hypercortisolism | Man with type 1 diabetes, ~2 mg weekly before holidays over five years. Cortisol above 1,750 nmol/L, glucose 41, ketones 4.2. Notably, the authors attribute a paradoxically high ACTH to the drug cross-reacting with the ACTH assay — meaning Melanotan II can distort endocrine bloodwork. |
We found no published sterility, endotoxin or microbial testing of marketed Melanotan II anywhere. Contamination risk is asserted by regulators and review authors rather than measured. That is a gap in the evidence, not a clean bill.
Regulatory status
Approval: none, anywhere. Not FDA, not the EMA, not the MHRA, not Health Canada, and explicitly not on Australia's register. Ireland's regulator puts it most bluntly — Melanotan 2 "is not authorised by the HPRA or any medicines regulator to treat any condition," with "no legitimate suppliers."
Canada, twice in one year
9 April 2026: Health Canada's advisory names "Melanotan I and II" among fourteen unauthorized injectable peptides. Research-use-only labelling, it says, "does not make these products legal or exempt from regulatory requirements."
13 July 2026: the same regulator approved a melanocortin drug. Scenesse — afamelanotide, which is Melanotan I — received a Notice of Compliance for preventing phototoxicity in erythropoietic protoporphyria. A 16 mg implant, placed under the skin by a trained clinician, every two months, for a rare disease in which patients cannot tolerate light at all. Not a tanning drug, not self-administered, and not this molecule.
Elsewhere
| Regulator | Action |
|---|---|
| TGA, Australia | August 2026 safety alert on inconsistently dosed nasal sprays; 27 infringement notices, A$101,412 |
| MHRA, UK | 16 adverse reaction reports 2012–2022; has "repeatedly taken action to remove Melanotan products from the market for over 10 years" |
| HPRA, Ireland | Over 500 listings removed from social media and marketplaces in a single year |
| US FDA | Warning letters 2007–2009; a 2016 debarment action against a seller citing false claims about reducing skin cancer rates |
Sport — prohibited, and the reason is instructive
Melanotan II is not named on the 2026 Prohibited List. It does not need to be. Section S0 prohibits at all times any substance "with no current approval by any governmental regulatory health authority for human therapeutic use." Melanotan II has no approval anywhere, so S0 captures it. Treat it as prohibited.
And here is the contrast worth carrying away. PT-141 is the same backbone with one functional group changed — and it is approved, so on the plain text of S0 it falls outside. Two nearly identical molecules, opposite anti-doping status, purely because one of them has a marketing authorisation.
Two sourcing notes. We verified the S0 wording against the 2019 List; the 2026 document itself we could not open, and while the wording has been stable across editions we have not confirmed it for the current one. Separately, Melanotan II was not among the seven peptides heard by FDA's compounding committee in July 2026 — but multiple legal analyses report it is queued for a second meeting expected before the end of February 2027. No FDA agenda was posted when we checked.
Sentient Biogenix supplies Melanotan II for laboratory research use only. It is not for human or veterinary use.
Questions we actually get
Does it actually tan you?
Almost certainly yes — MC1R agonism produces melanin, and the effect is consistently described after about five doses. What does not exist is a controlled trial showing it. The entire human tanning record for Melanotan II is three people in an uncontrolled 1996 pilot.
So what were all those tanning studies?
Melanotan I. Different molecule, linear, thirteen residues, 60% heavier. The "47% fewer sunburn cells" and "needed 50% more sun to match the controls" figures are all Melanotan I, at milligram daily doses. Melanotan I is now an approved medicine, given as a clinician-placed implant.
Is it safer than a sunbed?
The comparison is the wrong one, and the historical record shows why. Users did not swap sunbeds for Melanotan — they did both. In the published case reports of eruptive moles and melanoma, the patients were typically using sunbeds at the same time. The realistic comparison is Melanotan plus UV, not instead of it.
Does it protect against skin cancer?
No, and this is the claim regulators have actually gone after. The FDA listed "reducing skin cancer rates" among the false claims in a 2016 debarment action against a seller. The documented effect runs the other way: by making moles change rapidly, it degrades the visual signal used to catch melanoma early.
Will the pigmentation go away when I stop?
Partly. New moles often fade after stopping. But in one documented case, gum pigmentation was still present at three months. And fading pigment is not the same as reversing the event — a dysplastic mole that appeared does not un-appear, and both melanomas in the collated case series arose in moles that were already there.
Is it the same as PT-141, just cheaper?
Structurally almost, pharmacologically overlapping, practically no. PT-141 is approved, has a defined dose, published pharmacokinetics and a real label. Melanotan II has none of those and adds the pigmentary effects PT-141's approved use is not chasing. It is not a cheaper version of an approved drug; it is an unapproved one.
How much is actually in the vial?
Genuinely unknown without a lot-specific certificate. One analysis found 4.32 to 8.84 mg in vials sold as 10 mg. A regulator found 22 to 54 mg in sprays labelled 30 mg. Buy against a certificate, not a label.
References
- Breindahl T, Evans-Brown M, Hindersson P, et al. Identification and characterization by LC-UV-MS/MS of melanotan II skin-tanning products sold illegally on the Internet. Drug Testing and Analysis 2015;7(2):164–172. DOI 10.1002/dta.1655. kclpure.kcl.ac.uk — 4.32 to 8.84 mg in vials labelled 10 mg, and the impurity figures.
- Therapeutic Goods Administration (Australia). Melanotan II tanning peptide products found to be inconsistently dosed. Safety alert, 18 August 2026. tga.gov.au
- Hadley ME, Dorr RT. Melanocortin peptide therapeutics: historical milestones, clinical studies and commercialization. Peptides 2006;27(4):921–930. PMID 16412534. — the inventors' own split of the two analogues by indication.
- Dorr RT, Ertl G, Levine N, et al. Effects of a superpotent melanotropic peptide in combination with solar UV radiation on tanning of the skin in human volunteers. Archives of Dermatology 2004;140(7):827–835. PMID 15262693. jamanetwork.com — a Melanotan I study, frequently miscited in support of Melanotan II dosing.
- 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 Sciences 1996. PMID 8637402. pubmed.ncbi.nlm.nih.gov — the only human tanning study of Melanotan II. We could not open the abstract.
- Wessells H, Fuciarelli K, Hansen J, et al. Synthetic melanotropic peptide initiates erections in men with psychogenic erectile dysfunction: a double-blind, placebo controlled crossover study. Journal of Urology 1998;160(2):389–393. PMID 9679884. pubmed.ncbi.nlm.nih.gov
- Wessells H, Levine N, Hadley ME, Dorr R, Hruby V. Melanocortin receptor agonists, penile erection, and sexual motivation. International Journal of Impotence Research 2000;12(Suppl 4):S74–S79. DOI 10.1038/sj.ijir.3900582. nature.com
- Doedens L, Opperer F, Cai M, et al. Multiple N-methylation of MT-II backbone amide bonds leads to melanocortin receptor subtype hMC1R selectivity. Journal of the American Chemical Society 2010;132(23):8115–8128. DOI 10.1021/ja101428m. — the source for non-selectivity at MC1, MC3, MC4 and MC5.
- Burian EA, Burian JA. Eruptive melanocytic nevi: a review. American Journal of Clinical Dermatology 2019;20:669–682. cyberderm.net — the ten collated cases, the dysplasia rate and the two melanomas.
- Hjuler KF, Lorentzen HF. Melanoma associated with the use of melanotan-II. Dermatology 2014;228(1):34–36. PMID 24355990. pubmed.ncbi.nlm.nih.gov
- Hueso-Gabriel L, Bernabeu-Wittel J, Cabrera R, et al. Eruptive nevi after melanotan use. Actas Dermo-Sifiliográficas 2012;103:329–331. — more than a hundred new moles in four weeks; all ten biopsies dysplastic.
- Peters B, Hadimeri H, Wahlberg R, Afghahi H. Melanotan II: a possible cause of renal infarction. CEN Case Reports 2020;9(2):159–161. PMID 31953620. pmc.ncbi.nlm.nih.gov
- Bonchev A. Changes in oral mucosa associated with melanotan II injections: a case report. Life 2026;16(2):265. DOI 10.3390/life16020265. mdpi.com — the 400 mcg every-other-day exposure and the persistent gingival pigmentation.
- Health Canada. Think twice before injecting peptides bought online. Public advisory, 9 April 2026. recalls-rappels.canada.ca
- US Food and Drug Administration. SCENESSE (afamelanotide) prescribing information, 210797s007, 2024. accessdata.fda.gov — the approved melanocortin drug: implant, dose, and its own pigmentary-lesion surveillance requirement. Canadian Notice of Compliance issued 13 July 2026.
- World Anti-Doping Agency. Prohibited List, section S0. Wording verified against the 2019 edition.
Listed rather than hidden, what we could not check. We could not open the Dorr 1996 abstract, so the "three subjects" figure comes from secondary sources and we have no dose range for it. We could not open the rhabdomyolysis or encephalopathy case reports, so we report their existence and no clinical detail. Per-receptor potency figures sit behind a login and we would not invent them. No human pharmacokinetic study of Melanotan II exists that we could find, and both circulating half-life figures fail on inspection. We verified WADA's S0 wording against the 2019 List rather than the 2026 one. The reported second compounding-committee meeting comes from legal analyses, not a posted FDA agenda. And we found no published sterility or endotoxin testing of marketed product at all.
For laboratory research use only. Not for human or veterinary use. Nothing on this page is dosing guidance, and no figure here should be read as a recommendation.