MT-2 (Melanotan II)

What MT-2 is and how it works

MT-2 is melanotan II, a cyclic lactam-bridged heptapeptide analog of alpha-melanocyte-stimulating hormone with the published structure Ac-Nle4-Asp5-His6-D-Phe7-Arg8-Trp9-Lys10 alpha-MSH(4-10)-NH2. It was developed at the University of Arizona and first described in humans in a 1996 pilot phase I study.^[1] Pharmacologically it is a non-selective melanocortin agonist, which is the single fact that explains everything else about it: the same molecule reaches the receptor subtype that drives pigment production and the receptor subtypes expressed mainly in the central nervous system, so pigmentation, spontaneous erections, nausea and appetite effects all arrive together rather than separately.^[19]

Three identity boundaries have to be settled before any claim on this page means anything, because all three neighbours are routinely read across onto melanotan II and two of them are approved drugs.

Melanotan II is not afamelanotide. Afamelanotide — also called melanotan I or NDP-alpha-MSH, and marketed as SCENESSE — is a different molecule: linear rather than cyclic, selective for the melanocortin 1 receptor rather than non-selective, and an approved US drug for phototoxic reactions in erythropoietic protoporphyria, scoped in the regulatory section below. Several of the best-known "melanotan tanning trials" of the 1990s and 2000s administered melanotan I, and the amounts in them are several times higher; none is cited on this page, and none is evidence about this compound.

Melanotan II is not bremelanotide. Bremelanotide is a deaminated analog of melanotan II and an approved US drug for hypoactive sexual desire disorder in premenopausal women, also scoped below. It has its own page in this library, its own trials and its own label, and nothing transfers in either direction. The boundary is not academic: a forensic analysis of eight samples seized by police characterized melanotan II and bremelanotide in the same consignments.^[18]

Melanotan II is not endogenous alpha-MSH. Melanocortin-receptor biology is mechanism. It explains why a melanocortin agonist changes pigment — pigment change under this class is a predictable pharmacological consequence of agonism at melanocortin receptors, not an off-target surprise, and the same effect appears in the labeled adverse-effect profile of the approved analog. It is not by itself evidence that administering this particular peptide to a person does any particular thing.^[19]

What the research actually shows

The entire human trial record for melanotan II is four publications. A PubMed search on 1 September 2026 for ("melanotan II"[tiab] OR "melanotan-II"[tiab]) restricted to the clinical trial, controlled clinical trial and randomized controlled trial publication types returned exactly four records. All four come from the same University of Arizona group, all were published between 1996 and 2000, and together they enrolled roughly 23 people for at most two weeks each.

Tanning: three subjects, 1996. In a single-blind, alternating-day, placebo-controlled pilot phase I study, three normal male volunteers received subcutaneous melanotan II with stepwise escalation. Two of the three had increased pigmentation in the face, upper body and buttock, measured by quantitative reflectance and by visual perception one week after administration ended, and the authors wrote that melanotan II has tanning activity in humans given only five low amounts every other day.^[1] That is the whole of the published human tanning evidence, and PubMed types the study as a Clinical Trial and a Controlled Clinical Trial rather than as a Randomized Controlled Trial.

Erectile response: two crossover studies, ten men each. In men with psychogenic erectile dysfunction, a double-blind, placebo-controlled crossover study using RigiScan monitoring reported clinically apparent erections in 8 of 10 men, with mean duration of tip rigidity above 80% of 38.0 minutes versus 3.0 on placebo (p=0.0045).^[2] In men with organic risk factors, a second crossover study — the only record PubMed types as a Randomized Controlled Trial for this compound — reported erections after 12 of 19 administrations versus 1 of 21 placebo administrations, tip rigidity above 80% lasting 45.3 versus 1.9 minutes (P=0.047), and significantly higher reported sexual desire after the compound than after placebo.^[3] The pooled report of the same 20 men puts the desire figure at 13 of 19 administrations (68%) versus 4 of 21 placebo administrations (19%), P<0.01, on a questionnaire.^[4]

The published harm record is larger than the published efficacy record, and almost all of it is case reports. The most reproducible finding is what happens to moles. A man with a prior melanoma and multiple dysplastic naevi developed crops of new naevi with atypical clinical and histopathologic features while existing naevi darkened and acquired growth features; after the peptide was stopped, the naevi progressively lightened and lost those features, and the authors concluded that synthetic alpha-MSH peptides can drive proliferation of neoplastic melanocytic cells in predisposed patients.^[10] A separate report documents eruptive naevi and darkening of pre-existing naevi 24 hours after a single administration.^[11] A systematic review of eruptive melanocytic naevi assembled 93 articles and 179 patients, placed 41% of them in a combined category of immunosuppressive agents, chemotherapy or melanotan, found that 16% had at least one histologically confirmed dysplastic naevus, and recorded five associated melanomas.^[13]

Systemic toxicity is documented in single patients. The most strongly attributed report is a 39-year-old man who administered 6 mg, six times his own stated starting amount, and developed a sympathomimetic presentation with rhabdomyolysis and renal dysfunction; the injected material was confirmed as melanotan II by mass spectrometry against a reference standard, which is a stronger exposure attribution than most reports in this literature carry.^[5] Two separate reports describe ischemic priapism, one requiring operative decompression,^[6] and one in a patient who had not recovered erectile function at 4-week follow-up.^[7] A 2013 letter in Annals of Internal Medicine reports posterior reversible encephalopathy syndrome in association with melanotan; PubMed carries no abstract for it, so nothing beyond the fact of the report is stated here.^[8] A renal infarction report puts its own hedge in its title, calling the compound a possible cause.^[9]

What is in the vial is itself a published finding. A validated LC-UV and tandem mass spectrometry study of material labelled melanotan II found total content ranging from 4.32 to 8.84 mg where every source claimed 10 mg, and unknown impurities of 4.1% to 5.9% in two of the three sample sets.^[17] A separate forensic laboratory in another country characterized melanotan II alongside bremelanotide in the same seized consignments.^[18] These are analytical findings about unregulated material, not a quality checklist, and this page does not offer one.

Where the evidence is weak

There is no randomized controlled trial of melanotan II for tanning or cosmetic pigmentation. A PubMed search on 1 September 2026 for ("melanotan II"[tiab] OR "melanotan-II"[tiab]) AND (tanning OR pigmentation) AND randomized controlled trial[pt] returned 0 records. The same-session control of identical shape — the same query with hydroquinone substituted for the two melanotan terms — returned 58 records, so the query shape does find randomized pigmentation trials where they exist. Substituting the neighbouring melanocortin drugs is a weaker check, and it is worth stating precisely rather than rounding up: afamelanotide in that same shape returns 1 record, a 2015 randomized vitiligo trial, and bremelanotide returns 0, which is what a drug indicated for sexual desire rather than for pigment should return. Dropping the tanning-and-pigmentation clause raises those two to 3 and 11, but that is a different query shape and so validates nothing about this one. The melanotan sentence has to be scoped the way it is, because the same search without the tanning terms returns exactly one record, and that record is the 10-man erectile-dysfunction crossover.^[3] Anyone who says there are no randomized trials of melanotan II is wrong; anyone who says a randomized trial supports tanning with it is also wrong.

Total published human exposure is about 23 people, for at most two weeks, a quarter of a century ago, from one research group. No independent group has replicated the tanning finding in a published trial. A PubMed search on 1 September 2026 for ("melanotan II"[tiab] OR "melanotan-II"[tiab]) AND ("long-term"[tiab] OR follow-up studies[mh]) returned 12 records; on inspection every one is animal or mechanistic work or an unrelated survey of enhanced bodybuilders, and none is a long-term human safety or follow-up study of this compound.

The cancer question, stated as carefully as the evidence allows. Four separate things are true at once and are easy to collapse into one another.

First, individual melanomas have been reported in people who used melanotan. One is a histologically confirmed gluteal melanoma in a 20-year-old woman with Fitzpatrick skin type II, three months after a three-to-four-week course, whose authors wrote only that the compound's melanocyte stimulation and her sunbed use coincided.^[14] Another is an oral mucosal melanoma in a 22-year-old woman who used a melanotan II nasal spray, reported under a title that is itself a question rather than a claim.^[15] A 2017 review counted four case reports of melanoma emerging from existing moles during or shortly after melanotan use and stated in its own words that conclusive evidence linking these phenomena is lacking.^[16] Each of these is n=1, and in the reports with usable detail a concurrent sunbed or anabolic exposure is present. A case report can establish that something happened in one person; it cannot establish a rate and it cannot establish causation.

Second, the naevus signal is more robust than the melanoma signal, and is still built from case reports. Independent reports from several countries describe the same picture, one with a dechallenge response after the peptide was stopped.^[10] The systematic review that collected them recorded 16% of its 179 patients as having at least one histologically confirmed dysplastic naevus and five associated melanomas — then wrote the ceiling on its own inference: the nature of the data precluded assessment of risk of malignant transformation.^[13]

Third, the mechanism argues in both directions, which is why mechanism cannot settle this. Melanocortin agonism drives melanocyte proliferation, the proposed basis for the naevus findings; eumelanin is also photoprotective, and the possibility that synthetic alpha-MSH peptides might be protective against melanoma was explicitly postulated before these reports appeared.^[10] A mechanistic argument is a hypothesis about a direction, not a measurement of a risk.

Fourth, the epidemiology that would settle the question has not been done. A PubMed search on 1 September 2026 for ("melanotan"[tiab]) AND (cohort studies[mh] OR incidence[mh] OR "cohort"[tiab] OR epidemiolog*[tiab]) AND melanoma returned 0 records, against a same-session control of the same shape, (melanoma[tiab]) AND cohort studies[mh] AND incidence[mh], that returned 1,444.

The honest position is therefore neither of the two sentences people reach for. The published record does not establish that melanotan II causes melanoma. It also does not show an absence of harm: the naevus finding is reproducible across independent reports, melanomas have been reported, and the regulatory statement in the section below names melanoma among the serious adverse events published case reports discuss.

A fifth strand is more immediately useful than any of the four. Sequential videodermoscopy before and during use in one man found that the dermoscopic changes made it difficult to differentiate a naevus from a melanoma.^[12] Independently of whether this compound changes melanoma risk, it degrades the standard clinical method for catching melanoma early.

Nobody knows what the material actually is, from batch to batch. The laboratory analysis above found stated and measured content disagreeing by more than a factor of two across sources, and unknown impurities present at several percent.^[17] Every human safety figure on this page was generated with characterized peptide in a research setting.

Almost everything known about how the compound is actually used comes from reading forums. A qualitative thematic analysis of 623 discussion entries from 205 participants identified motivation, misinformation, preparation, dosing regimens, sunbed use, side effects and concerning practices as its themes, and the authors' own point was that the covert nature of use makes both its extent and its side-effect profile hard to assess.^[20] Themes extracted from anonymous posts describe a subculture; they are not evidence about a drug, and none of the regimens in them appears on this page.

Legal and regulatory status

Melanotan II is not approved by the FDA for any indication, and the human evidence for it is preliminary. Verified on 1 September 2026 against Drugs@FDA, approved labeling and the National Drug Code directory, with every null run alongside a same-session positive control of identical shape. Drugs@FDA and approved labeling return nothing. The NDC directory does return five melanotan records, and the marketing-category field on each is what makes them meaningful: every one is a bulk active-ingredient registration rather than a finished drug — four as bulk ingredient, one as bulk ingredient for human prescription compounding. Filtered to human prescription drugs, melanotan returns nothing, while the identically shaped query for bremelanotide returns the approved product. Melanotan II appears in the federal drug registers only as a registered bulk substance, never as an approved human medicine.

FDA has published its own risk statement about this compound. On the agency's page titled "Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks", content current as of 22 April 2026, Melanotan II appears on the table headed "Bulk drug substances nominated but withdrawn" — substances FDA describes as previously in category 2 of the interim policies and withdrawn by their nominators. FDA's entry reads, verbatim: "Compounded drugs containing Melanotan II may pose risk for immunogenicity for certain routes of administration due to the potential for aggregation or peptide-related impurities. Published case reports discuss serious adverse events including melanoma, posterior reversible encephalopathy syndrome, sympathomimetic toxidrome and priapism."

Three precisions about that fact matter. It sits on the withdrawn table, not on that same page's separate table of substances currently under category 2 of the interim policies — two different tables with two different meanings. That web page is also a separate document from FDA's 503A and 503B bulk drug substance category lists; both were searched on 1 September 2026 with in-document positive controls, and melanotan appears in neither. And a withdrawn nomination is not an approval, not a compounding authorization and not a safety clearance: it records that someone proposed the substance, that FDA stated safety concerns, and that the proposal was withdrawn.

FDA's enforcement database is not evidence of FDA action against this molecule. Three drug-enforcement records name melanotan products; all three are Class II recalls initiated by compounding pharmacies over sterility assurance and manufacturing deviations, and one of the three is for melanotan I. Those are findings about how particular batches were made.

Two neighbouring molecules are approved and this one is not. Afamelanotide is approved under NDA 210797 for phototoxic reactions in erythropoietic protoporphyria and bremelanotide under NDA 210557 for hypoactive sexual desire disorder in premenopausal women. Neither approval reaches melanotan II and neither one's safety record is admissible as evidence about it.

Anti-doping status, verified in this session. The 2026 WADA International Standard Prohibited List and the 2026 Monitoring Program were retrieved on 1 September 2026 through the USADA prohibited-list page and the WADA-hosted PDF assets it links, then converted and full-text searched. "Melanotan", "melanotide", "melanocortin" and "afamelanotide" return zero hits on the List, and "melanotan" returns zero hits on the Monitoring Program, with in-document positive controls firing on both. Melanotan II is therefore not named on either document. Absence from the List is never a statement that a substance is permitted. The provision that reaches it is S0 Non-Approved Substances, prohibited at all times and all Specified Substances, whose own trigger reads: "Any pharmacological substance which is not addressed by any of the subsequent sections of the List and with no current approval by any governmental regulatory health authority for human therapeutic use (e.g. drugs under pre-clinical or clinical development or discontinued, designer drugs, substances approved only for veterinary use) is prohibited at all times." That trigger turns on this molecule's own approval status, verified above as none. It is not lifted by the two neighbouring approvals, because those are different substances.

Non-US advisories: what could and could not be retrieved. A GOV.UK search for melanotan on 1 September 2026 returned nine results, none of them a live MHRA safety alert about melanotan, so no MHRA advisory is asserted here. Four attempts to reach Australia's TGA the same day returned HTTP status 000 and zero bytes, which is a fact about a network route rather than about any document, so nothing is asserted about a TGA position either way. What can be sourced is what the dermatology literature says about regulators rather than what a regulator document says: a 2017 review states in its own words that multiple national health organizations have issued safety warnings regarding the use of melanotan I and II.^[16]

One registered trial exists and it is not a cosmetic one. A ClinicalTrials.gov search for melanotan on 1 September 2026 returned a single study: a phase 2 randomized trial of melanotan II as an adjunct to narrowband UV-B phototherapy for repigmentation in stable nonsegmental vitiligo, currently recruiting, with no results posted and its intervention recorded only as administered per protocol.

PHL does not sell peptides, does not prescribe, and takes no position on how any material reaches anyone.

Questions to bring to a provider

The productive conversation about this compound is a dermatological one before it is anything else, because the reproducible published finding is what it does to moles.

• Given that new and darkening naevi are the most consistently reported effect in the literature, is a baseline full-skin examination and mole mapping worth having on record before anything else?^[10][13]
• Does a personal or family history of melanoma, dysplastic naevi, or a fair skin type change how a clinician would view this entirely?^[10]
• Sequential dermoscopy in one published case found the changes made a naevus hard to distinguish from a melanoma. What does that mean for how any future mole check should be interpreted, and should any clinician doing that check be told about past use?^[12]
• The published human record is roughly 23 people over at most two weeks, in studies from 1996 to 2000. What would it take for that to count as an adequate safety base for a cosmetic decision?^[1]
• Severe nausea affected about one in eight subjects at the most-studied amount, and the highest amount tested produced dose-limiting somnolence. Are those the effects being expected, and what is the plan if they occur?^[4][1]
• Priapism, rhabdomyolysis with renal dysfunction, and a posterior reversible encephalopathy syndrome case have all been published. Which of these would warrant an emergency department rather than a phone call?^[6][5][8]
• A validated laboratory analysis found stated and measured content disagreeing by more than a factor of two, and unknown impurities at several percent. What does that do to any risk conversation about an unregulated peptide?^[17]

This page grades the compound overall as anecdotal rather than by its best result, and the reason is worth stating so the badge is legible. The claim people arrive with is the cosmetic one, and the evidence behind that claim is a three-person, non-randomized phase I study from 1996. The one randomized controlled trial in the record is a ten-man erectile-dysfunction crossover, and grading the compound on it would put a badge earned by one claim above prose about a different one. The strongest, most reproducible published signal here is not an efficacy signal at all.