Dashnaiv Peptides
Compounds·melanocortin agonists·non-selective melanocortin receptor agonist

Melanotan II ('tanning injections', the Barbie drug): what four small trials found, why it was abandoned, and what the case reports and vials show

What 646 indexed publications and 1 randomized trials actually state about melanotan ii, sentence by sentence, each tied to its source and labeled by the kind of evidence it is.

Human clinical trial Reviewed 41 sources Updated

At a glance

Evidence availability
Human clinical evidence
Strongest tier in the indexed literature
Indexed publications
646
Europe PMC, title or abstract, 2026-09-14
Human studies in ledger
8
1 randomized; study count, not efficacy proof
Approval
none found
no registered development programme
Routes reported
intranasal, oral, subcutaneous
from studies in this ledger
Studied in
Humans, Mice, Rats, Zebrafish
20 primary studies in the evidence table
Reviewed by Adam Mirando, PharmD, on . What changed

What melanotan II is, and what happened to it

Melanotan II is a peptide in the melanocortin agonists class (non-selective melanocortin receptor agonist). Europe PMC indexes 646 publications naming it or a listed alias in a title or abstract, including 1 randomized controlled trials and 6 clinical trials of any design, as of . The strongest evidence tier in that literature is human clinical trials.

This page reports what those studies state, sentence by sentence, with each statement tied to its source and labeled by the kind of evidence it is. It does not recommend use, and it does not translate study doses into anything personal.

What the evidence level means

Publication counts show what is indexed, not how strong the evidence is. The ledger below separates human clinical records from preclinical, analytical, and in-vitro work.

Human clinical studies in this ledger81 randomized · 7 other human clinical
Evidence strengthNot yet assessedSeparate from evidence availability
Efficacy signalNot yet assessedRead the study result, not the tier alone

Interpretation boundary: An indexed publication count is a discovery measure. It does not establish efficacy, safety, approval, or a personal treatment plan.

Melanotan II in two minutes

What it is. A cyclic copy of the pigment hormone α-MSH, made in Arizona in the late 1980s to give a sunless tan and prevent skin cancer. It turned out to hit the brain's melanocortin receptors too, producing erections, nausea, yawning and appetite loss.

What the research actually shows. 646 indexed publications, most about its use as a laboratory tool in rodents. Four human trials, all from the inventors' group, in 3 to 20 men: a two-week pilot at 0.01 to 0.03 mg/kg that darkened skin in two of three, and three erection studies at 0.025 mg/kg in which most men had erections lasting 40 minutes, two thirds reported more desire, and one in eight had severe nausea. No tanning trial was ever run.

What happened to it. Abandoned as too non-selective. Its metabolite became PT-141 (bremelanotide, approved 2019 for low desire); its linear cousin became afamelanotide (Scenesse, approved for a rare light-sensitivity disease). Melanotan II itself is illegal to sell in the UK, US and Australia.

What the case reports add. Priapism needing surgery; darker, larger and new moles; brown gums after 64 days of use; a mucosal melanoma in the mouth of a 22-year-old after nasal use. Online vials held 4 to 9 mg with impurities.

Where the evidence is thinnest. Long-term melanoma risk, which no one has measured; and everything about the loading-and-maintenance schedules, which no one has tested.

Editorial synthesis Written from general pharmacology, the development record and what is commonly reported; not a cited finding. Cited findings on this page carry their own tier.

How it works

Written from general pharmacology and the development record, and marked as editorial synthesis; the measurements behind it are quoted in the biomarker section.

  • Melanotan II is a cyclic heptapeptide, Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2, built by Victor Hruby and Mac Hadley's group at the University of Arizona in the late 1980s from the active core of α-melanocyte-stimulating hormone (residues 4 to 10), with a lactam bridge for stability and a D-phenylalanine for potency. The aim was a sunless tan to prevent skin cancer. The lactam ring made it 'superpotent' at pigment receptors and, unexpectedly, at the brain's melanocortin receptors too.Editorial synthesis
    Editorial synthesis from general knowledge
  • It is non-selective. At MC1 receptors on melanocytes it drives eumelanin synthesis, which darkens skin, moles, freckles and, in the 2026 case report, gums. At MC4 receptors in the hypothalamus it suppresses appetite and, through a spinal pathway, produces erections; at MC3 and MC4 it produces the yawning, stretching and nausea that every trial recorded. In mice it also triggers mast cells to release histamine through a receptor outside the melanocortin family, causing a sharp drop in temperature. Every effect users report, wanted and unwanted, is on this list.Editorial synthesis
    Editorial synthesis from general knowledge
  • The non-selectivity is why it was abandoned and why its descendants succeeded. The erection effect was carried forward as bremelanotide (PT-141), melanotan II's own deamidated metabolite, approved in 2019 for low sexual desire in premenopausal women. The tanning aim was carried forward as afamelanotide (melanotan I), a linear analogue selective for MC1, approved for erythropoietic protoporphyria. Melanotan II itself never had a tanning trial and was never submitted for approval anywhere.Editorial synthesis
    Editorial synthesis from general knowledge

What happened in the human studies?

This record's ledger holds 8 primary human studies, of which 4 are trials. Few enough to show in full: each card quotes what its abstract reported about Melanotan II. Read them before any other section on this page.

  • Controlled clinical trial humans n = 20 2000 Human clinical trial
    Increased sexual desire was reported after 13/19 (68%) doses of Melanotan II vs 4/21 (19%) of placebo (P<0.01).
    Source pmid-11035391 · quoted verbatim from the abstract
  • Randomized controlled trial humans 2000 Human clinical trial
    The mean duration of tip rigidity greater than 80% was 45.3 minutes with Melanotan II versus 1.9 for placebo (P = 0.047).
    Source pmid-11018622 · quoted verbatim from the abstract
  • Controlled clinical trial humans n = 10 1998 Human clinical trial
    Mean duration of tip rigidity greater than 80% was 38.0 minutes with Melanotan-II and 3.0 with placebo (p=0.0045).
    Source pmid-9679884 · quoted verbatim from the abstract
  • Phase 1 clinical trial humans 1996 Human clinical trial
    Two subjects had increased pigmentation in the face, upper body and buttock, as measured by quantitative reflectance and by visual perception 1 week after MT-II dosing ended.
    Source pmid-8637402 · quoted verbatim from the abstract
  • Case report humans 2026 Observational, human
    The lesions were almost symmetrically distributed, with a more intense coloration in the anterior region of the lower jaw.
    Source pmid-41752902 · quoted verbatim from the abstract
  • Case report humans 2025 Observational, human
    The case of a 22-year-old female who developed a mass in the anterior maxilla after using Melanotan II, a nasal spray containing a synthetic analogue of melanocyte-stimulating hormone, is reported.
    Source pmid-40210573 · quoted verbatim from the abstract
  • Case report humans 2024 Observational, human
    Mass spectrometric analysis of melanotan II was challenging, as it is a small peptide with a molecular weight of 1024 Da, which is significantly heavier than classical drugs that the laboratory usually handles.
    Source pmid-39302005 · quoted verbatim from the abstract
  • Case report humans 2021 Observational, human
    Melanotan II, an injectable melanocortin analog, is illicitly available on the internet to generate a sunless tan through melanocyte induction.
    Source pmid-33460908 · quoted verbatim from the abstract

Trial by trial: what melanotan II did in the men who received it, and what the case reports say since

The complete human record: four small studies from the 1990s, then the harms reported from unregulated use.

Human trials of melanotan II, all from the University of Arizona group.
StudyParticipantsDose and routeDesignResult
Dorr 1996 (phase 1 pilot)3 healthy men0.01 mg/kg SC, weekdays, 2 weeks; escalated to 0.025 or 0.03 mg/kgSingle-blind, alternating salinePigmentation of face, upper body and buttocks in 2 of 3; spontaneous erections 1 to 5 hours after dosing; mild nausea at most doses; grade II sleepiness at 0.03 mg/kg
Wessells 199810 men with psychogenic erectile dysfunction0.025 mg/kg SCDouble-blind placebo crossover, 6-hour RigiScanErections in 8 of 10; 38 minutes of full rigidity vs 3 on placebo; nausea, yawning, less appetite
Wessells 200010 men with organic erectile dysfunction0.025 mg/kg SC, twice each for drug and placeboDouble-blind placebo crossoverErections after 12 of 19 injections vs 1 of 21 placebo; 45 minutes of rigidity; desire higher; nausea and yawning
Wessells 2000 (pooled review)20 men with erectile dysfunction0.025 mg/kg SCPooled crossover dataErections in 17 of 20 without stimulation; desire after 68% of doses vs 19%; severe nausea in 12.9%
Published reports from unregulated use.
ReportWhoProduct and routeWhat happened
Bonchev 2026One user, 64 days of self-injection for tanningSubcutaneous vialsSymmetrical brown pigmentation of the gums and cheeks; followed for three months after stopping
Yassin Alsabbagh 202522-year-old woman using a nasal spray for tanningNasal sprayMucosal malignant melanoma of the upper jaw; surgery and immunotherapy
Mallory 2021One manSubcutaneous injectionIschaemic priapism, failed standard management, surgical decompression; the third published priapism report
Breindahl 2015Vials bought from three online shopsInjectable powder4.3 to 8.8 mg of melanotan II per vial; impurities of 4 to 6% in two of three shops
Gilhooley 2021623 forum entries from 205 users, UK and IrelandMostly injectionsMotivations and side effects catalogued: nausea, flushing, mole darkening, erections, appetite loss
Deville 2024Seized vialsInjectable powderForensic identification; the peptide is hard to detect with standard drug screens

The tanning trial that a reader would expect at the top of this table does not exist. The inventors measured pigment in three men for two weeks and then studied erections; the tanning use was invented by the market.

Editorial synthesis Written from general pharmacology, the development record and what is commonly reported; not a cited finding. Cited findings on this page carry their own tier.

What the evidence shows

One row per primary study in this record's ledger. Fields are read from each paper's indexing and abstract. "Analytical method" marks papers about detecting or measuring the compound rather than about its effects.

20 primary studies in this record's ledger, strongest evidence first. A dash means the abstract did not state the value.
StudyDesignnSpeciesDoseRouteDurationReported outcomeTier
Wessells 2000 Controlled clinical trial 20 Humans——— Increased sexual desire was reported after 13/19 (68%) doses of Melanotan II vs 4/21 (19%) of placebo (P<0.01). Human clinical trial
Wessells 2000 Randomized controlled trial — Humans0.025 mg/kgsubcutaneous— The mean duration of tip rigidity greater than 80% was 45.3 minutes with Melanotan II versus 1.9 for placebo (P = 0.047). Human clinical trial
Wessells 1998 Controlled clinical trial 10 Humans——— Mean duration of tip rigidity greater than 80% was 38.0 minutes with Melanotan-II and 3.0 with placebo (p=0.0045). Human clinical trial
Dorr 1996 Phase 1 clinical trial — Humans0.01 mg/kg; 0.025 mg/kg/daysubcutaneous1 week Two subjects had increased pigmentation in the face, upper body and buttock, as measured by quantitative reflectance and by visual perception 1 week after MT-II dosing ended. Human clinical trial
Bonchev 2026 Case report — Humans—oral64 days The lesions were almost symmetrically distributed, with a more intense coloration in the anterior region of the lower jaw. Observational, human
Yassin 2025 Case report — Humans—intranasal— — Observational, human
Deville 2024 Case report — Humans——— Mass spectrometric analysis of melanotan II was challenging, as it is a small peptide with a molecular weight of 1024 Da, which is significantly heavier than classical drugs that the laboratory usually handles. Observational, human
Mallory 2021 Case report — Humans—subcutaneous— — Observational, human
Merlino 2026 Animal study — ———— — Animal, preclinical
Inozemtseva 2024 Animal study — Rats——— We found that chronic treatment with Semax and MTII reversed or substantially attenuated CUS-induced anhedonia, BW gain suppression, adrenal hypertrophy and a decrease in the hippocampal levels of BDNF. Animal, preclinical
Liu 2024 Animal study — Mice——— Strikingly, promoting wheel-running activity in Htr2cF327L/Y mice results in a decrease in HFD consumption and improved glucose homeostasis. Animal, preclinical
Ford 2024 Animal study — ———— However, during social interactions, MTII selectively increased oxytocin-dependent activation of nucleus accumbens, a site critical for social learning. Animal, preclinical
Eliason 2022 Animal study — Mice——— MT-II injected into the NAcc significantly decreased consumption in both home cage and operant paradigms, and furthermore decreased appetitive responding to gain access to food. Animal, preclinical
Hong 2021 Animal study — Zebrafish——— Using α-MSH human form as a standard, we could identify derivatives that induced greater physiological effects; particularly, the synthetic analogue melanotan-II (MT-II) exhibited a higher capacity for melanophore… Animal, preclinical
Fortin 2021 Animal study — Mice——— — Animal, preclinical
René 2021 Animal study — Mice——— Interestingly, the expression of the WT-hMC4R in mice revealed lower sensitivity of the human receptor to α-melanocyte-stimulating hormone (α-MSH) but not β-MSH or melanotan II, resulting in a lower penetrance obese… Animal, preclinical
Chen 2020 Analytical method — Mice——— — Animal, preclinical
Wu 2020 Animal study — Mice——— By immunoblot and immunohistochemical analysis, it was found that MTII dose-dependently increased the phosphatase and tensin homolog (PTEN) protein level while reducing PTEN phosphorylation, which resulted in the… Animal, preclinical
Minakova 2019 Animal study — Mice——— Normal background C57 male mice treated with MT-II showed no significant alteration in social behavioral metrics. Animal, preclinical
Cote 2018 Animal study — ———— Interestingly, systolic and mean arterial pressure (MAP) was lower in the TRF group. Animal, preclinical

Doses reported in studies

Each entry is a sentence quoted from the study's abstract, with the study's design, sample size and year in front of it. Comparator doses in the same sentence are not attributed to melanotan ii.

  • In the phase 1 pilot, three men received 0.01 mg/kg subcutaneously on alternate weekdays for two weeks, escalated to 0.025 or 0.03 mg/kg.Human clinical trial
    Source pmid-8637402
  • Men with erectile dysfunction received 0.025 mg/kg subcutaneously, twice each for drug and placebo.Human clinical trial
    Source pmid-11018622
  • The 1998 trial in ten men with psychogenic erectile dysfunction used the same 0.025 mg/kg dose.Human clinical trial
    Source pmid-9679884
  • In mice, 120 micrograms per kilogram a day by intravenous infusion for seven days reduced food intake and transiently raised blood pressure and heart rate.Animal, preclinical
    Source pmid-29351428

Every melanotan II dose in the trials, in one table

Every figure here is a trial dose, given by body weight to men in erection and pilot studies. The loading and maintenance schedules were never tested.

Doses of melanotan II administered in studies.
SettingRouteDoseSchedulePopulation
Phase 1 pilot (1996)Subcutaneous0.01 mg/kg, rising by 0.005 to 0.025 or 0.03 mg/kgWeekdays, alternating with saline, 2 weeks3 healthy men
Erection trials (1998, 2000)Subcutaneous0.025 mg/kgSingle doses, repeated on separate daysMen with erectile dysfunction
Mice (2018)Intravenous infusion120 mcg/kg/day7 daysAppetite and blood-pressure study
Mice (2018)IntraperitonealNot stated in the abstractSingleHypothermia via mast cells
Rats (1994)OralNot stated in the abstractSingle4.6% oral bioavailability

Figures for the loading and maintenance schedules circulate on forums and vendor pages. None was tested in a study, so none is reproduced here; the table holds every dose a study actually gave. For scale, the trial dose for a 75 kg man is about 1.9 mg, given for research under monitoring, and the analysed vials held 4 to 9 mg of uncertain purity. Nothing on this page is an instruction to take anything.

Editorial synthesis Written from general pharmacology, the development record and what is commonly reported; not a cited finding. Cited findings on this page carry their own tier.

Side effects: what the trials recorded, and what the case reports added

From the trials: nausea (severe in one in eight at the erection dose), yawning and stretching, spontaneous erections, sleepiness at the top dose, and darkening skin. From case reports since: priapism needing surgery, darkening and new moles, gum pigmentation, and a mucosal melanoma after nasal use, in people using unregulated product with sunbeds. Events and their frequency as each study reported them, with the denominator where the abstract gives one.

  • At 0.025 mg/kg, nausea and yawning were frequent and one in eight subjects had severe nausea.Human clinical trial
    Source pmid-11035391
  • Nausea, stretching and yawning, and decreased appetite were more frequent than placebo in the 1998 trial; none needed treatment.Human clinical trial
    Source pmid-9679884
  • The 0.03 mg/kg dose caused grade II sleepiness and fatigue in one of two men; mild nausea occurred at most doses.Human clinical trial
    Source pmid-8637402
  • A 2026 case report describes symmetrical brown pigmentation of the gums and cheeks after 64 days of self-injection for tanning.Observational, human
    Source pmid-41752902
  • A 2025 case report describes a mucosal malignant melanoma of the upper jaw in a 22-year-old woman who had used melanotan II nasal spray for tanning.Observational, human
    Source pmid-40210573
  • Ischaemic priapism requiring surgical decompression followed a subcutaneous injection in a 2021 case report, the third such report.Observational, human
    Source pmid-33460908
  • Online vials analysed in 2015 contained 4.3 to 8.8 mg of melanotan II with impurities up to 5.9 percent from two of three shops.Mechanistic, in vitro
    Source pmid-24771717
  • In mice, melanotan II causes profound transient hypothermia by activating mast cells and releasing histamine, independent of the melanocortin receptors.Animal, preclinical
    Source pmid-29812984
  • Melanoma risk is the question the trials could not address and the case reports cannot settle. Melanotan II acts on the receptor that governs melanocyte pigment production, reliably darkens and enlarges moles, and has been the subject of melanoma case reports since 2012 (not yet in the ledger) in users who also used sunbeds; the 2025 oral mucosal melanoma after nasal use is the first in a site the sun does not reach. Rhabdomyolysis at overdose is described in case reports vendors cite that are not in the ledger. No cohort has been followed, so the risk is neither measured nor excluded.Editorial synthesis
    Editorial synthesis from general knowledge · primary document to be added to the ledger

Who melanotan II is discussed for, and the cautions that recur

Studied: healthy men and men with erectile dysfunction, for days. Never studied: women, anyone for tanning, anyone for more than two weeks, anyone by nasal spray. Community: people who want a tan without sun, and people using it for libido or appetite suppression.

The cautions come from the trials, the case reports and the pharmacology:

  • Moles, freckles and melanoma. It darkens and enlarges existing moles and creates new pigmented spots, which hides melanoma and mimics it. Melanoma case reports exist, most with sunbed use; the 2025 oral mucosal melanoma after nasal use is in a site the sun does not reach. Anyone with many moles, fair skin or a family history of melanoma has the strongest reason to avoid it, and any user needs a skin check by someone who knows what it does.
  • Priapism. Erections without stimulation were a trial finding; ischaemic priapism needing surgery is a case-report finding. Men with sickle-cell trait or prior priapism are at particular risk.
  • Nausea and sleepiness. Severe nausea in one in eight at the erection dose; sleepiness at the top pilot dose.
  • Blood pressure and heart rate. MC4 agonists raise both in rodents; the trials did not report cardiovascular measures, and no user has been monitored.
  • Vial contents. Analysed vials held variable amounts with impurities; the product is illegal to sell, so nobody is accountable for it.
  • Pregnancy, children and women generally. No study included a woman; the nasal-spray melanoma case was a 22-year-old woman.

Editorial synthesis Written from general pharmacology, the development record and what is commonly reported; not a cited finding. Cited findings on this page carry their own tier.

Reported interactions

Sentences in which the compound is studied alongside another agent. Read the quotation: the word interaction can also be statistical.

  • Animal study mice 2015 Animal, preclinical
    In the present report, a mouse model of binge EtOH drinking was employed to determine whether the MCR agonist, melanotan-II (MTII), would improve the effectiveness of NAL in reducing excessive binge-like EtOH drinking when these drugs were co-administered prior to EtOH access.
    Source pmid-26108334 · quoted verbatim from the abstract

Reported timelines

Onset, peak and duration figures as each study reported them.

  • Erections lasted about 38 to 45 minutes of full rigidity within a six-hour window after a dose.Human clinical trial
    Source pmid-11018622
  • Spontaneous erections came intermittently for one to five hours after dosing, preceded by stretching and yawning.Human clinical trial
    Source pmid-8637402
  • Pigmentation appeared within the two-week pilot in two of three men.Human clinical trial
    Source pmid-8637402
  • In rats, oral bioavailability was 4.6 percent, which the developers read as a possible oral route.Animal, preclinical
    Source pmid-7983590

What is measured over time, and what is not

The trials measured hours. Yawning and stretching came first, then erections, intermittently for one to five hours after a dose, with about 40 minutes of full rigidity inside a six-hour window. Pigmentation appeared within the two-week pilot in two of three men, and that is the whole of the tanning time-course in the literature. Everything users know about how fast a tan appears, how long it lasts and how often to inject comes from each other; the case reports add that gum pigmentation was still present three months after stopping. Melanoma, the outcome that matters, would need years of follow-up in a cohort that has never been assembled.

Editorial synthesis Written from general pharmacology, the development record and what is commonly reported; not a cited finding. Cited findings on this page carry their own tier.

Escalation schedules used in studies

How trials stepped doses, reported as study design.

  • The phase 1 pilot escalated by 0.005 mg/kg steps from 0.01 mg/kg to 0.025 or 0.03 mg/kg over two weeks.Human clinical trial
    Source pmid-8637402

Study durations

Treatment and follow-up periods as stated in each abstract.

  • Two weeks of alternate-day dosing in the pilot; single doses with six hours of monitoring in the erection trials.Human clinical trial
    Source pmid-8637402
  • The 2026 case report followed a user who injected for 64 days, then for three months after stopping.Observational, human
    Source pmid-41752902

Routes: subcutaneous injection in every trial; nasal sprays untested and now in a case report

Subcutaneous injection in all four trials. Nasal sprays were never studied; the one published account of nasal melanotan II is a 2025 case report of a mucosal melanoma in the mouth of a 22-year-old user. Routes of administration named in each study.

  • Randomized controlled trial humans 2000 Human clinical trial
    administration by subcutaneous route reported
    Melanotan II (0.025 mg/kg) and vehicle were each administered twice by subcutaneous injection; real-time RigiScan monitoring and a visual analog were used to quantify the erections during a 6-hour period.
    Source pmid-11018622 · quoted verbatim from the abstract
  • Phase 1 clinical trial humans 1996 Human clinical trial
    administration by subcutaneous route reported
    Subcutaneous injections of MT-II or saline were given daily (Monday-Friday) for 2 consecutive weeks.
    Source pmid-8637402 · quoted verbatim from the abstract
  • Case report humans 2026 Observational, human
    administration by oral route reported
    To date, there is a lack of published data specifically addressing the timeline for resolution of oral pigmentation associated with Melanotan II use, making this case a valuable contribution to the limited existing literature on the subject.
    Source pmid-41752902 · quoted verbatim from the abstract
  • Case report humans 2025 Observational, human
    administration by intranasal route reported
    The case of a 22-year-old female who developed a mass in the anterior maxilla after using Melanotan II, a nasal spray containing a synthetic analogue of melanocyte-stimulating hormone, is reported.
    Source pmid-40210573 · quoted verbatim from the abstract
  • Case report humans 2021 Observational, human
    administration by subcutaneous route reported
    We describe in this case report a patient presenting with acute ischemic priapism after subcutaneous injection of melanotan II.
    Source pmid-33460908 · quoted verbatim from the abstract
  • Nasal sprays have never been studied; the one published account is the 2025 mucosal melanoma case report.Editorial synthesis
    Editorial synthesis from general knowledge

Weight-normalized doses, as published

Per-kilogram figures exactly as each study published them, for the species it studied.

  • 0.01 to 0.03 mg/kg subcutaneous in the phase 1 pilot; 0.025 mg/kg in the erection trials.Human clinical trial
    Source pmid-8637402
  • 120 micrograms per kilogram a day intravenous in mice.Animal, preclinical
    Source pmid-29351428

Weight-normalized figures above are reproduced exactly as each study published them, for the species it studied. Dose does not scale linearly with body mass between species: metabolic rate, clearance and receptor density differ, and regulatory guidance uses allometric, not proportional, conversion. A mg/kg figure from a rat study is a fact about that rat study and nothing else.

What people report outside the literature

Forum reports describe loading doses daily for a week or two, then weekly maintenance, with nausea, flushing, darker moles and freckles, spontaneous erections and appetite loss; a 2021 study of 623 forum entries catalogued the same. None of that schedule was ever tested in a study. What circulates in user communities and clinic marketing, reported so a reader knows the figures and their origin. None of it has been tested in a trial, and none of it is a suggestion.

  • Melanotan II circulates as 'tanning injections', 'tan jabs' or the 'Barbie drug', injected subcutaneously in a daily loading phase then weekly maintenance, and lately as nasal sprays, sold through social media and websites in defiance of prohibitions in the UK, Australia and the United States. A 2021 study of 623 forum entries catalogued the motivations (a tan without sun, confidence, appetite loss, libido) and the side effects users describe: nausea, flushing, darker and new moles and freckles, spontaneous erections, tiredness. Users also describe the uncertainty of what a vial holds, which the 2015 analysis confirmed. None of the schedules people follow was ever tested in a study; the trials dosed by body weight for erection research and stopped. The figures that circulate are not reproduced here.Editorial synthesis
    Editorial synthesis from general knowledge
Method note · shared across compounds

Reconstitution mathematics

Lyophilised peptide is supplied as a mass in a vial and dissolved in a stated volume of diluent. Two figures follow from that and nothing else:

  • Concentration = mass in vial ÷ diluent volume. A 5 mg vial in 2 mL is 2.5 mg/mL, or 2,500 mcg/mL.
  • Volume for a given mass = that mass ÷ concentration. 250 mcg at 2,500 mcg/mL is 0.1 mL. On a U-100 insulin syringe, where 1 mL is 100 units, that is 10 units.

Study doses on this page are quoted as published, in the units the authors used. Converting between mcg, mg and IU, or between a mass and a syringe volume, is arithmetic; deciding a mass is not, and this page does not do it. The reconstitution calculator performs the conversion with the formula shown.

Method note · shared across compounds

Reading a certificate of analysis

A certificate of analysis is a laboratory report on one batch. Reading it means checking four things in order.

  1. Identity. Mass spectrometry should report an observed molecular mass matching the peptide's theoretical mass within the instrument's stated tolerance. A certificate with no mass spectrometry, or one that lists only the expected value, has not confirmed identity.
  2. Purity. HPLC purity is the area of the main peak as a share of all peaks, at a stated wavelength. It says nothing about what the other peaks are, and it is not a measure of quantity.
  3. Quantity. Net peptide content, by amino acid analysis or UV, is the fraction of the vial's mass that is peptide rather than counter-ions and water. A 5 mg vial at 80% net content holds 4 mg of peptide, and every concentration figure above changes accordingly.
  4. Provenance. The batch number on the certificate should match the vial, the laboratory should be named and independent of the seller, and the test date should be recent.

This page rates no supplier and links to none. It describes how to read the document.

Method note · shared across compounds

Equipment described in studies

Published human studies of injectable peptides report the same small set of materials: single-use insulin syringes with fixed needles, most often U-100 with 29 to 31 gauge needles; bacteriostatic water or sterile water for injection as diluent, with the choice stated in the methods; alcohol swabs; and refrigerated storage of reconstituted solution. Animal studies more often report intraperitoneal or intragastric administration and state the vehicle used. Where a study in this record's ledger names its materials or vehicle, that sentence appears under storage or routes above; where it does not, nothing is assumed here.

Storage and handling

No storage study for human use exists. The 2015 vial analysis and the 2024 forensic report describe a lyophilised peptide that is hard to identify with standard drug screens and variable in content; the 1994 preformulation study measured its chemistry for a dosage form that was never made. Vendor handling instructions describe a product whose sale is illegal in the countries most buyers live in.

Editorial synthesis Written from general pharmacology, the development record and what is commonly reported; not a cited finding. Cited findings on this page carry their own tier.

Common mistakes in how melanotan II is discussed

  1. Assuming a tanning trial exists. It does not. Pigmentation was an observation in three men over two weeks; the human trials were about erections.
  2. Confusing it with afamelanotide (Scenesse). That is melanotan I, a different, MC1-selective molecule approved for a rare disease. Melanotan II has no approval anywhere.
  3. Confusing it with PT-141. Bremelanotide is melanotan II's metabolite, developed separately and approved for low desire in women. The approval does not transfer to the parent.
  4. Calling it 'research use only'. It is an unlicensed medicine whose sale is illegal in the UK, US and Australia; the label is a legal fiction the 2021 forum study found users themselves saw through.
  5. Treating loading and maintenance doses as protocol. Both are community inventions. The trial dose was 0.025 mg/kg, for erections, under monitoring.
  6. Reading the melanoma question as settled either way. No cohort has been followed. The mechanism, the mole changes and the case reports are the reasons dermatologists advise against it; the absence of a study is not the absence of a risk.

Editorial synthesis Written from general pharmacology, the development record and what is commonly reported; not a cited finding. Cited findings on this page carry their own tier.

Melanotan II vs melanotan I (afamelanotide, Scenesse), PT-141 and UV tanning

Melanotan II beside its descendants and alternatives.
AgentWhat it isHuman evidenceStatus
Melanotan IICyclic α-MSH(4-10) analogue; non-selective melanocortin agonistFour trials in 3 to 20 men (1996 to 2000); case reports of harmNever approved; illegal to sell in the UK, US and Australia
Afamelanotide (melanotan I, Scenesse)Linear α-MSH analogue selective for MC1R; implantPhase 3 trials in erythropoietic protoporphyriaApproved (EU 2014, FDA 2019) for EPP; no record on this site
Bremelanotide (PT-141)Melanotan II's deamidated metabolite; MC4-preferring; 127 indexed publications14 randomized trials; approved 2019 for hypoactive sexual desire in premenopausal womenPrescription medicine (Vyleesi)
UV tanning (sun, sunbeds)Ultraviolet-induced melaninDecades of epidemiology: a proven cause of melanomaSunbeds banned for minors in many countries
Dihydroxyacetone self-tannersSurface stain of the outer skin layerCosmetic safety record; no pigment biologyApproved cosmetic ingredient

The 'melanotan 1 vs 2' question has a plain answer: one became an approved medicine for a rare disease by being selective, the other stayed a laboratory compound by being unselective, and only the second is sold for tanning. The PT-141 comparison runs the same way: the approved drug is the metabolite, refined for one receptor and one use.

Editorial synthesis Written from general pharmacology, the development record and what is commonly reported; not a cited finding. Cited findings on this page carry their own tier.

Other compounds in its class

Same class in the registry: Bremelanotide. Each row shows what that compound's own record states; nothing is inferred across rows.

2 compounds in the melanocortin agonists class. Each row states what that compound's own record says; nothing is inferred across rows.
CompoundTierPublicationsRCTsRecord
Melanotan II Human clinical trial 646 1 draft
Bremelanotide Approved label 127 14 draft

Regulatory status: unlicensed and illegal to sell in the UK, US and Australia; never approved anywhere

Registry facts only. Jurisdiction-level status, compounding categories and sport prohibitions need their own cited documents before they appear here.

  • Never approved anywhere and never submitted. Development at Competitive Technologies and the University of Arizona ended in the early 2000s; the erection programme became bremelanotide (Vyleesi, approved 2019) and the tanning programme became afamelanotide (Scenesse, approved in the EU in 2014 and by FDA in 2019 for erythropoietic protoporphyria), both different molecules. Melanotan II is an unlicensed medicine whose sale is illegal in the United Kingdom (MHRA warning, 2008), Australia and the United States (FDA warning letter, 2009); it is sold anyway as a research chemical and, increasingly, as a nasal spray. Not named on the WADA Prohibited List; as an unapproved substance it falls under S0, and its appetite and pigment effects give it no sporting rationale.Editorial synthesis
    Editorial synthesis from general knowledge · primary document to be added to the ledger

Open questions and limitations

What is genuinely unknown, stated plainly. A missing field is not evidence that the outcome is safe, effective, or established.

  • No tanning trial, no study in women, no study longer than two weeks and no cohort followed for melanoma exists.
  • The MHRA 2008 warning, FDA 2009 warning letter, TGA position and the rhabdomyolysis reports are cited from summaries and are not in the ledger. The melanoma and naevus case reports of 2012 and 2013 were added to it on 29 September 2026: Ong 2012 (melanoma in situ), Mang 2012 (dermoscopic change in naevi), Reid 2013 (atypical naevi) and Hjuler 2013 (melanoma).
  • Thirteen alias-matched sources (metallothionein II, myotoxin II, V5/MT) were removed by hand; the fetcher's publication counts still include them.

Questions people ask

Does melanotan II cause melanoma?

Unproven and not ruled out. Case reports describe melanomas diagnosed in users, a 2025 report describes a mucosal melanoma in the mouth of a 22-year-old after nasal use, and the drug reliably darkens and enlarges moles, which can hide or mimic melanoma. Most reported users also used sunbeds. No study has followed users long enough to measure risk in either direction; the melanocortin-1 receptor melanotan II activates is the receptor that governs pigment, and melanocytes are the cells melanoma comes from.

What is melanotan II?

Melanotan II is a synthetic cyclic peptide copied from the active core of the pigment hormone α-MSH, made at the University of Arizona in the late 1980s as a possible sunless tanning agent to prevent skin cancer. It activates several melanocortin receptors at once: MC1R in skin, which darkens pigment, and MC3 and MC4 in the brain, which produce erections, nausea, yawning and appetite loss. It was tested in a handful of men in the 1990s, never developed further, and is now sold illegally online as the 'Barbie drug' for tanning.

What is the half-life of melanotan II?

Not stated in any abstract in the ledger. The erection trials monitored effects for six hours after a subcutaneous dose, and the phase 1 pilot reported spontaneous erections for one to five hours after dosing; a 1994 preformulation study measured 4.6 percent oral bioavailability in rats. The tan itself persists for weeks because it is melanin in the skin, not the drug in the blood, which is why users move to weekly maintenance.

Is melanotan II hard on the kidneys?

No trial measured kidney function, and no case report in the ledger describes kidney injury. Vendor pages mention rhabdomyolysis at overdose, which would strain the kidneys; that claim comes from case reports not in this record and is unverified here. What the trials did record was nausea, yawning, erections and sleepiness at the top dose.

Does melanotan II burn fat?

In mice and rats, yes: melanotan II activates the MC4 receptor that suppresses appetite, and chronic infusion reduced food intake and body fat in several rodent studies in the ledger. In people the trials recorded decreased appetite as a side effect and measured nothing about weight; no human study has tested it for fat loss, and its effects on heart rate and blood pressure in rodents are the reason MC4 agonists for obesity have been hard to develop.

Can melanotan II change eye colour?

No study has reported it, and the biology runs the other way: melanotan II stimulates melanin production, which darkens, not lightens. Forum reports of eye changes exist; the ledger has none, and a pigment-stimulating drug acting on the iris would be a reason for concern rather than a feature.

Has melanotan II been tested in humans?

In four small studies in the 1990s, all from the University of Arizona group that made it: a two-week phase 1 pilot in three men and three double-blind erection studies in 10 to 20 men with erectile dysfunction at 0.025 mg/kg. No tanning trial was run, no woman was enrolled, and nobody was dosed for more than two weeks. Everything since is case reports of harm from unregulated use.

What dose was used in the trials?

0.01 mg/kg subcutaneously rising to 0.025 or 0.03 mg/kg in the pilot, and 0.025 mg/kg in the erection studies, about 1.9 mg for a 75 kg man, given as single doses under monitoring. The loading-then-maintenance schedules on vendor pages were never tested; analysed online vials held 4.3 to 8.8 mg with impurities.

What are the side effects of melanotan II?

In the trials: nausea (severe in one in eight at 0.025 mg/kg), yawning and stretching, spontaneous erections lasting hours, appetite loss, skin darkening, and sleepiness at 0.03 mg/kg. In case reports: priapism needing surgery, darker and new moles, brown pigmentation of the gums, and a mucosal melanoma in the mouth after nasal use. In mice, hypothermia via histamine release.

Does melanotan II cause cancer?

Not established and not excluded. It acts on the receptor that drives melanocyte pigment, reliably changes moles, and has been linked in case reports to melanomas, most in sunbed users; a 2025 report describes an oral mucosal melanoma after nasal spray. No cohort of users has ever been followed, so the risk has not been measured in either direction.

What is the difference between melanotan 1 and melanotan 2?

Melanotan I is a linear α-MSH analogue selective for the pigment receptor MC1R; it became afamelanotide (Scenesse), approved for erythropoietic protoporphyria. Melanotan II is a cyclic analogue that also hits the brain's MC3 and MC4 receptors, hence erections, nausea and appetite loss; it was never approved and is the one sold for tanning.

Is melanotan II the same as PT-141?

No, though they are related: bremelanotide (PT-141) is melanotan II's deamidated metabolite, developed separately for its erection and desire effects and approved in 2019 for low sexual desire in premenopausal women. The approval belongs to the metabolite, not the parent.

Is melanotan II legal?

No. It has never been approved anywhere and is an unlicensed medicine whose sale for human use is illegal in the United Kingdom (MHRA warning 2008), Australia and the United States (FDA warning letter 2009). It is sold anyway online as a 'research chemical' and, increasingly, as a nasal spray.

Do melanotan II nasal sprays work?

No study has tested any nasal product. The trials used subcutaneous injection. The one published account of nasal melanotan II is a 2025 case report of a mucosal melanoma in the upper jaw of a 22-year-old who used a spray for tanning.

How long does melanotan II take to tan?

The only measurement is the two-week pilot, in which two of three men had visibly darker skin on the face, upper body and buttocks. Everything else about onset, depth and fade comes from users; the tan persists for weeks because it is melanin in the skin, not drug in the blood.

Does melanotan II help with weight loss?

In rodents it suppresses appetite through the MC4 receptor and reduces body fat, while raising heart rate and blood pressure. In men the trials recorded decreased appetite as a side effect and measured nothing about weight. No human study has tested it for fat loss.

Why does melanotan II cause erections and nausea?

Because it is not selective. The same MC4 receptors that suppress appetite drive erections through a spinal pathway, and MC3 and MC4 activation in the brainstem produces yawning, stretching and nausea. The inventors' erection trials exist because the pilot volunteers reported spontaneous erections.

Which species has melanotan II been studied in?

Humans, in four small trials; mice and rats extensively as a laboratory tool for the melanocortin system (appetite, blood pressure, hypothermia, autism and alcohol models); zebrafish; dogs. Much of the ledger is rodent pharmacology in which melanotan II is the probe, not the subject.

Sources

Full citations. Every claim above links to one of these by its id.

  1. 1
  2. 2
  3. 3
  4. 4
  5. 5
    Barbie drug identification: Not a child's play.
    pmid-39302005 · · peer-reviewed
  6. 6
  7. 7
  8. 8
  9. 9
  10. 10
  11. 11
  12. 12
Show the remaining 29 sources
  1. 13
  2. 14
  3. 15
    Melanotan Tanning Injection: A Rare Cause of Priapism.
    pmid-33460908 · · peer-reviewed
  4. 16
  5. 17
  6. 18
  7. 19
  8. 20
  9. 21
  10. 22
  11. 23
  12. 24
  13. 25
  14. 26
  15. 27
  16. 28
  17. 29
  18. 30
  19. 31
    Melanoma associated with the use of melanotan-II.
    pmid-24355990 · · peer-reviewed
  20. 32
    Atypical melanocytic naevi following melanotan injection.
    pmid-23914578 · · peer-reviewed
  21. 33
  22. 34
    Melanotan-associated melanoma in situ.
    pmid-22724573 · · peer-reviewed
  23. 35
    Sympathetic and sensory innervation of brown adipose tissue.
    pmid-20935665 · · peer-reviewed
  24. 36
    The first preparative solution phase synthesis of melanotan II.
    pmid-19043625 · · peer-reviewed
  25. 37
  26. 38
  27. 39
  28. 40
  29. 41

Reference card

Reference card · generated /compounds/melanotan-ii
Compound
Melanotan II, melanocortin agonists
Evidence tier
Human clinical trial
Indexed publications
646 · 1 RCTs · 6 other clinical trials
Approval
no registered development programme found
Routes reported
intranasal, oral, subcutaneous
Reviewed
Adam Mirando, PharmD,

Study figures are as published in each source and are not recommendations. Print or save this card with its date.

Last reviewed and what changed

Newest first. These are the record's own revision dates, and the same dates feed the sitemap.

  1. · Reviewed by Adam Mirando, PharmD, on 2026-09-29.
  2. · The four melanoma and naevus case reports the page cited from summaries are now in the ledger: Ong 2012 (pmid-22724573), Mang 2012 (pmid-23052015), Reid 2013 (pmid-23914578) and Hjuler 2013 (pmid-24355990). An open action had named one of them as 'Ong and Bygrave'; the authors are Ong and Bowling.
  3. · Reverted 1 of those label changes after tightening the rule: 'urine' had matched inside 'murine' and 'screening' had matched a zebrafish drug screen. pmid-34502223 back to Animal study
  4. · Label correction: 2 evidence rows built from detection and doping-control papers carried study designs such as animal or in-vitro work. They are relabelled Analytical method, the label scripts/draft_claims.py has applied since the rule was added; these rows predate it. pmid-34502223 (Animal study -> Analytical method); pmid-32674774 (Animal study -> Analytical method)
  5. · Stage 0 cleaned by hand: thirteen sources and their rows matched by the alias 'MT-II' (metallothionein II, myotoxin II, V5/MT, a genotype paper) removed. Written under the sequencing rule after research/intents/melanotan-ii.json: guide (8 sections incl. a four-trial table and a case-report table), FAQ to 12 plus 8 from the map, dose, weight-normalized, duration, timeline and adverse-event claims from the abstracts, mechanism, reported-use, regulatory (illegal to sell in the UK, US and Australia; descendants approved) with pending_source; intent-driven H1 and title.
  6. · Claims drafted extractively from 50 ledger sources by scripts/draft_claims.py: 39 claims, 25 evidence-table rows. Status researched -> draft.
  7. · Claims drafted extractively from 50 ledger sources by scripts/draft_claims.py: 50 claims, 25 evidence-table rows. Status researched -> draft.
  8. · Evidence fetched from Europe PMC and ChEMBL by scripts/fetch_evidence.py; claims not yet written.