Synthetic cyclic alpha-MSH analogue and nonselective melanocortin receptor agonist
Melanotan II
Not FDA approved
An unapproved peptide often discussed for tanning. It has also been studied for erectile responses.
7-minute readFull profile reviewed July 25, 2026
Evidence is explained by question. Dosing references show their own check dates.
60-second overview
Melanotan II at a glance
Why people look into it, what studies found, and what is still unknown.
Why people look into it
Skin pigmentation and sexual responses, alongside nausea and other unwanted effects.
What studies found
Very small studies found pigmentation and erectile responses. Safety information also comes from individual reports and product testing.
What is still unclear
Repeated-use safety and long-term skin and other risks remain uncertain. Darker skin from MT-2 has not been shown to protect against UV injury.
About the evidence and review date
Educational information only. Evidence reviewed through July 25, 2026. Published studies, sponsor announcements, and trials without results are labeled separately. Evidence gaps apply to the specific finding beside them.
Research questions
Why people research it
Each label shows how much evidence supports that question.
Skin pigmentationEarly human evidence
Erectile response in menEarly human evidence
Sexual desire in menEarly human evidence
Vitiligo repigmentation with narrowband UV-BCurrently being studied
Weight lossNot demonstrated
Sunburn or skin-cancer protectionNot demonstrated
What studies show
What the evidence supports
The research behind the answer
Two ten-person placebo-controlled crossover erectile-response studies
and one three-person pigmentation Phase 1 pilot.
See each finding and its sources (14)
Mechanistic rationale
Melanotan II is a synthetic cyclic alpha-MSH analogue that activates multiple melanocortin receptors.
MT-2 is not receptor-selective like the practical shorthand often used for MT-1. Its melanocortin activity helps explain pigmentation, nausea, appetite effects, yawning, erections, and sexual-desire signals.
Receptor activity explains biological plausibility; it does not establish a safe consumer product, approved indication, or predictable result.
Peer reviewedPeptide description and observed human effects
Controlled human study
MT-2 produced measurable pigmentation in a three-person pilot human study.
Two participants were visibly and instrumentally darker after the short Phase 1 experiment.
Three men are not enough to define effectiveness, a safe regimen, skin-cancer risk, or results across skin types and product formulations.
Small controlled studies found that MT-2 initiated erections in men with psychogenic or organic erectile dysfunction.
Each crossover study enrolled ten men and used short-term rigidity monitoring after MT-2 and placebo.
These were small early experiments, not approval trials. They do not establish long-term safety, repeated-use effectiveness, or a recommendation for sexual dysfunction.
One small controlled study reported higher sexual-desire ratings after MT-2 than placebo.
The organic-ED crossover study recorded increased desire alongside erectile responses.
Ten male participants and a six-hour observation period cannot establish a general libido treatment, outcomes in women, durability, or clinical benefit.
FDA identifies potential significant safety concerns for compounded MT-2, including immunogenicity and published serious adverse-event reports.
FDA specifically points to aggregation or peptide-related impurities and reports involving melanoma, posterior reversible encephalopathy syndrome, sympathomimetic toxidrome, and priapism.
FDA's risk entry is not an incidence estimate and does not prove causality for every reported event.
Peer reviewedCase presentation and operative management
Other human evidence
Melanoma reports after melanotan exposure are concerning signals but do not prove that MT-2 causes melanoma.
A 2025 report described oral mucosal melanoma after nasal-spray use, and FDA cites melanoma among published serious-event reports.
Temporal association in individual cases cannot separate MT-2 from UV exposure, natural disease, patient risk factors, or uncertain product composition.
Human weight-loss evidence for MT-2 has not been demonstrated.
Reduced appetite appeared as a short-term effect in early human experiments, while weight and fat-loss claims primarily come from animal research or anecdotes.
An appetite side effect is not a controlled weight-management outcome and does not establish durable benefit or acceptable risk.
Peer reviewedPilot endpoints did not include weight management
Peer reviewedReduced appetite reported as an adverse effect
Registered trial — no results
A 2026 registered Phase 2 vitiligo study has no posted results.
The sponsor-submitted ClinicalTrials.gov record plans to compare MT-2 plus narrowband UV-B with placebo plus narrowband UV-B.
A registry listing is not evidence of efficacy, completion, peer review, product quality, or regulatory endorsement.
Peer reviewedReference-standard identification and purity result
No direct evidence located
No regulator-approved MT-2 reconstitution, storage, stability, or consumer dosing standard was identified.
Published experiments describe research-protocol injections, but MT-2 has no approved U.S. product label that validates instructions for vials, nasal sprays, or other retail forms.
Vendor instructions and community practices are not equivalent to validated pharmaceutical stability, sterility, or dosing data.
Missing reports do not establish safety. Findings apply to the product, route, amounts, population, comparison, and follow-up studied.
Side-effect frequency, study withdrawals, and gaps
How often side effects occurred
The available information does not reliably show how often particular side effects occur.
Evidence boundary
Under-detected or under-reported events must not be described as rare.
Why people stopped in studies
Relay has not verified which side effects led people to stop treatment in studies.
Evidence boundary
This is an evidence gap, not proof that discontinuations did not occur.
Emergency instructions
This profile does not contain verified, product-specific emergency instructions.
Evidence boundary
Relay does not infer emergency guidance from study discontinuations, mechanism, or incomplete adverse-event reporting.
Dosing references
Dosing & preparation
Each table labels its source and applies only to the named route, product, or study. An online example or community report is not an approved dose.
Route: SubQ · Under the skin
Human study · source-specific regimenWhat this means
Amounts reported in a human study. A studied amount is not automatically an approved dose or a recommendation for an individual.
Melanotan II · three-person Phase 1 pilot
A 1996 pilot alternated active MT-II and saline in three healthy male volunteers.
Pilot starting amount
0.01 mg/kg initial active dose
Frequency
Active and saline on alternating weekdays
Treatment period
2 weeks; 5 active exposures
Melanotan II · three-person Phase 1 pilot
Stage / period
Amount in source
Frequency
2 weeks; 5 active exposures
0.01 mg/kg initial active dose
Active and saline on alternating weekdays
Active doses increased by 0.005 mg/kg to 0.025 or 0.03 mg/kg. Fatigue, sleepiness, nausea, and erections were reported. This tiny pilot does not establish a safe tanning regimen.
This source does not establish a mixing volume or storage period for independently sourced powder. Use formulation-specific instructions; the study amount alone is not a reconstitution recipe.
Concentration = total mass ÷ final volume. The calculator performs user-entered math; it does not choose a dose or diluent.
Melanotan II is a cyclic heptapeptide alpha-MSH analogue with agonist
activity across MC1R, MC3R, MC4R, and MC5R-related pathways. A
three-person Phase 1 pilot recorded pigmentation, nausea, fatigue or
somnolence, yawning, and spontaneous erections. Two ten-person
placebo-controlled crossover studies found erectogenic and
sexual-desire signals in men with erectile dysfunction. No modern
pivotal efficacy or long-term safety program was located. FDA
identifies immunogenicity, aggregation, peptide-related impurities, and
serious published adverse-event reports as compounding concerns. Case
reports describe rhabdomyolysis, renal injury or infarction, priapism,
and temporally associated melanoma, without establishing incidence or
certain causality.
Why this matters
A plausible mechanism can explain why a study was attempted. It does not prove that the compound improves a human outcome.
Signals and targets
MC1RMC3RMC4RMC5R
Proposed biological steps
MC1R-related melanogenesis and pigmentation
Central MC3R/MC4R-related appetite and sexual-response signaling
Broader nonselective melanocortin agonism
Research reference
How mature is the evidence?
A reference for the studies, populations, and routes behind this profile.
Research depthSparse early human research
Human administration evidence consists mainly of three tiny 1990s SubQ studies, while current development and safety information includes a registered trial, case reports, and product-quality findings.
Why this matters
Research depth describes how large and mature the overall record is. It does not tell you whether the results were positive.
Evidence confidenceVery low for clinical use
No approved product, modern confirmatory program, established long-term safety dataset, or validated retail formulation exists.
Why this matters
Confidence describes how reliable and consistent the conclusions are. It can be high for one outcome and low for another.
Strongest evidenceThree controlled or saline-comparator studies totaling 23 menWhy this matters
The strongest evidence type shows what the best-supported conclusions are actually based on.
Human evidenceDirect but extremely small, short, old, and limited to SubQ research exposuresWhy this matters
Human findings are more directly relevant than animal or laboratory results, but they still apply only to the populations and outcomes studied.
Schedules studiedOne monitored exposure on each active study occasion; Six-hour monitoring after each intervention
Amounts studiedWithheld: this record provides research context without a transferable amountWhy this matters
These are exposures used in cited research for a specific route and population—not an instruction for an individual.
Half-lifeNot established for this exact editorial recordWhy this matters
Half-life describes how long it takes the measured amount in the body to fall by half. It is not a dosing recommendation.
Route evidenceA small controlled crossover study investigated short-term erectile and adverse-effect responses in men with psychogenic erectile dysfunction.Why this matters
Evidence can change by administration method. Findings from one route should not automatically be applied to another.
Evidence boundary: Only ten men were studied, with six hours of monitoring per condition. The record does not establish long-term treatment, tanning safety, outcomes in broader populations, or equivalence to unregulated products. Amounts shown describe cited research exposure—not a dosage recommendation.
Studies
Study-by-study record
Study arms are reported for transparency. They describe what researchers did in a defined record and do not transfer across identities, routes, formulations, or populations.
Why this matters
A later trial phase can ask a more mature question, but it does not guarantee a positive result, regulatory approval, or relevance outside the studied population.
Controlled human studyPeer reviewed
Effect of an alpha-melanocyte stimulating hormone analog on penile erection and sexual desire in men with organic erectile dysfunction
DurationSix-hour monitoring after each intervention
Design and population
Double-blind, placebo-controlled crossover study
Ten men with erectile dysfunction and organic risk factors
Outcomes measured
Subject-reported erections
Penile rigidity measured by RigiScan
Sexual desire
Adverse effects
What was reported
Erections and sexual-desire ratings occurred more often after MT-II than placebo. Nausea and yawning were frequent, and four of nineteen MT-II exposures caused severe nausea.
Study administration and important limits
Study administration: Two protocol-defined 0.025 mg/kg subcutaneous MT-II exposures and two vehicle exposures per participant
Limitations: Only ten men were enrolled. Monitoring lasted six hours, repeated-use safety was not established, and the findings do not validate recreational products or establish an approved sexual-function treatment.
Controlled human studyPeer reviewed
Synthetic melanotropic peptide initiates erections in men with psychogenic erectile dysfunction: double-blind, placebo controlled crossover study
DurationSix-hour monitoring after each intervention
Design and population
Double-blind, placebo-controlled crossover study
Ten men with psychogenic erectile dysfunction
Outcomes measured
Penile rigidity measured by RigiScan
Clinically apparent erections
Adverse effects
What was reported
Eight of ten men developed clinically apparent erections after MT-II. Mean time with high tip rigidity was longer than with placebo.
Study administration and important limits
Study administration: A protocol-defined 0.025 mg/kg subcutaneous MT-II exposure and vehicle placebo on separate study occasions
Limitations: This was a small, short crossover experiment from 1998—not an approval trial, not long-term treatment evidence, and not a dosing recommendation. Nausea, yawning, stretching, and reduced appetite occurred more often with MT-II.
Controlled human studyPeer reviewed
Evaluation of melanotan-II, a superpotent cyclic melanotropic peptide in a pilot phase-I clinical study
DurationTwo treatment weeks with follow-up after dosing
Design and population
Single-blind, alternating-day, saline-controlled dose-escalation pilot
Three healthy male volunteers
Outcomes measured
Skin pigmentation by reflectance and visual assessment
Tolerability
Spontaneous erections
What was reported
Two of three participants showed increased pigmentation after the study. Nausea was common, one participant developed grade II somnolence and fatigue at the highest studied level, and spontaneous erections occurred.
Study administration and important limits
Study administration: Subcutaneous MT-II or saline on alternating weekdays; MT-II was escalated from 0.01 mg/kg to 0.025 or 0.03 mg/kg under the study protocol
Limitations: This was a three-person 1996 pilot in men, far too small and short to establish a safe or effective tanning regimen, long-term safety, outcomes in women, or equivalence to products currently sold as MT-2.
Other human evidencePeer reviewed
Melanotan II nasal spray: a possible risk factor for oral mucosal malignant melanoma?
One 22-year-old woman with oral mucosal malignant melanoma after reported MT-II nasal-spray use
Outcomes measured
Oral mucosal melanoma diagnosis
What was reported
The report documents temporal exposure before diagnosis and discusses MT-II as a possible risk factor.
Study administration and important limits
Study administration: Reported unlicensed nasal-spray exposure
Limitations: A single case cannot establish that MT-II caused melanoma. Route, product identity, dose, other risk factors, and the natural occurrence of disease prevent causal inference.
Laboratory identification and purity analysis of submitted material
One analyzed vial labeled Melanotan II
Outcomes measured
Chemical identity
Measured purity
What was reported
Reference-standard mass spectrometry confirmed MT-II in the vial, but measured purity was only 30%.
Study administration and important limits
Study administration: No clinical intervention
Limitations: One forensic sample does not describe every vendor or product. It demonstrates why a label alone cannot establish identity, concentration, purity, sterility, or safety.
Other human evidencePeer reviewed
Melanotan Tanning Injection: A Rare Cause of Priapism
One man with prolonged ischemic priapism after a tanning injection
Outcomes measured
Ischemic priapism
Response to emergency treatment
What was reported
The report described prolonged ischemic priapism that did not resolve with initial treatment and required surgical decompression.
Study administration and important limits
Study administration: Reported Melanotan II tanning-product exposure
Limitations: This rare case cannot estimate incidence or confirm the composition of the product, but it is consistent with the erectogenic pharmacology observed in controlled human studies.
Other human evidencePeer reviewed
Melanotan II: a possible cause of renal infarction: review of the literature and case report
One person with renal infarction after reported MT-II use
Outcomes measured
Renal infarction
Kidney injury
What was reported
The authors reported a renal infarction they considered most likely related to MT-II exposure.
Study administration and important limits
Study administration: Reported Melanotan II exposure
Limitations: This is a single observational case. It raises a safety signal but cannot prove causality, estimate frequency, or separate peptide effects from product-quality and patient-specific factors.
Other human evidencePeer reviewed
Melanotan II injection resulting in systemic toxicity and rhabdomyolysis
DurationAcute presentation and hospital evaluation
Design and population
Emergency-department case report
One 39-year-old man after self-injecting Internet-purchased material labeled Melanotan II
Outcomes measured
Systemic toxicity
Rhabdomyolysis
Renal function
Sympathomimetic symptoms
What was reported
The report described anxiety, sweating, diffuse pain, sympathomimetic toxicity, rhabdomyolysis, and renal dysfunction after exposure.
Study administration and important limits
Study administration: Unregulated self-administered product exposure
Limitations: A single case cannot establish incidence or prove that chemically verified MT-II alone caused the event. The product was Internet-purchased, so identity, purity, contamination, and actual dose were uncertain.
Registered trial — no resultsTrial registry
Melanotan II as an Adjunct to NB-UVB Phototherapy for Repigmentation in Stable Nonsegmental Vitiligo
Planned enrollment of adults with stable nonsegmental vitiligo
Outcomes measured
Vitiligo Area Scoring Index
Repigmentation
Melanin index
Dermatology quality of life
Adverse events and dermatologic changes
What was reported
No results were posted by the July 25, 2026 evidence cutoff.
Study administration and important limits
Study administration: Investigational MT-II or placebo as an adjunct to standardized narrowband UV-B phototherapy
Limitations: ClinicalTrials.gov displays information submitted by the sponsor. Registration does not show that the trial will finish, that its product is equivalent to retail MT-2, that the treatment works, or that any regulator has endorsed it.
Community
Experience reports stay separate from published evidence
Loading Community Intelligence…
Built by the community
Help strengthen the Melanotan II experience record
Every structured report adds useful context about research setup, outcomes, and unwanted effects as the community dataset grows.
Publicly anonymous by default. Your account keeps reports editable and helps reduce duplicate submissions.
Where to go next
Keep the question moving
Move from one profile into a direct comparison, a multi-compound evidence map, or a related record.