Melanotan-2

1. Studied for

   Erectile function and sexual desire in men (human trials)

   In 2 double-blind, placebo-controlled, crossover human trials from the same research group, subcutaneous Melanotan-II reliably triggered penile erections without any deliberate sexual stimulation, measured objectively with a RigiScan monitor rather than by self-report alone. In the first trial, in 10 men with erectile dysfunction of no identified organic cause, 8 of 10 developed clinically apparent erections after Melanotan-II, with tip rigidity above 80% lasting a mean of 38.0 minutes versus 3.0 minutes after placebo; nausea, a stretching-and-yawning complex, and decreased appetite were reported more often after Melanotan-II than after placebo. In the second trial, in 10 men whose erectile dysfunction had an identified organic risk factor, Melanotan-II started subjectively reported erections in 12 of 19 uses versus 1 of 21 placebo uses, mean tip rigidity above 80% lasted 45.3 minutes versus 1.9 minutes, and reported sexual desire was higher after Melanotan-II than after placebo; several uses were associated with severe nausea. A third paper by the same group pools both trials into a combined 20-man dataset and restates the same findings; it is not independent evidence. Together these are the strongest primary human data that exist for this compound by name, not for a related molecule. HUMAN 2 double-blind, placebo-controlled, crossover human trials, 10 men each (the first in psychogenic erectile dysfunction, the second in men with organic risk factors), plus a pooled restatement of both by the same authors Preclinical strong Convergent results from more than one independent, well-designed human trial. Still the ceiling of what this page shows: 'strong' here never means the compound is an approved or recommended treatment. Open for the full finding and the paper it came from.

   In the literature

   Erectile function and sexual desire in men (human trials)

   In 2 double-blind, placebo-controlled, crossover human trials from the same research group, subcutaneous Melanotan-II reliably triggered penile erections without any deliberate sexual stimulation, measured objectively with a RigiScan monitor rather than by self-report alone. In the first trial, in 10 men with erectile dysfunction of no identified organic cause, 8 of 10 developed clinically apparent erections after Melanotan-II, with tip rigidity above 80% lasting a mean of 38.0 minutes versus 3.0 minutes after placebo; nausea, a stretching-and-yawning complex, and decreased appetite were reported more often after Melanotan-II than after placebo. In the second trial, in 10 men whose erectile dysfunction had an identified organic risk factor, Melanotan-II started subjectively reported erections in 12 of 19 uses versus 1 of 21 placebo uses, mean tip rigidity above 80% lasted 45.3 minutes versus 1.9 minutes, and reported sexual desire was higher after Melanotan-II than after placebo; several uses were associated with severe nausea. A third paper by the same group pools both trials into a combined 20-man dataset and restates the same findings; it is not independent evidence. Together these are the strongest primary human data that exist for this compound by name, not for a related molecule.^{References 1, 2, 3}

   Model2 double-blind, placebo-controlled, crossover human trials, 10 men each (the first in psychogenic erectile dysfunction, the second in men with organic risk factors), plus a pooled restatement of both by the same authors

   Confidence: strong

   Convergent results from more than one independent, well-designed human trial. Still the ceiling of what this page shows: 'strong' here never means the compound is an approved or recommended treatment.

   Source

   Wessells H, Fuciarelli K, Hansen J, Hadley ME, Hruby VJ, Dorr R, Levine N. Synthetic melanotropic peptide initiates erections in men with psychogenic erectile dysfunction: double-blind, placebo controlled crossover study. J Urol. 1998;160(2):389-393. DOI 10.1097/00005392-199808000-00025. PMID 9679884. Wessells H, Gralnek D, Dorr R, Hruby VJ, Hadley ME, Levine N. Effect of an alpha-melanocyte stimulating hormone analog on penile erection and sexual desire in men with organic erectile dysfunction. Urology. 2000;56(4):641-646. DOI 10.1016/s0090-4295(00)00680-4. PMID 11018622. Restatement, not independent: Wessells H, Levine N, Hadley ME, Dorr R, Hruby V. Melanocortin receptor agonists, penile erection, and sexual motivation: human studies with Melanotan II. Int J Impot Res. 2000;12(Suppl 4):S74-S79. DOI 10.1038/sj.ijir.3900582. PMID 11035391.

   PubMed 9679884 PubMed 11018622 PubMed 11035391

   How this citation was checked

   All 3 re-resolved live via PubMed esummary/efetch and Crossref. The 1998 abstract confirms 8 of 10 men developing clinically apparent erections and the 38.0-versus-3.0-minute tip-rigidity result. The 2000 Urology abstract confirms the 12-of-19-versus-1-of-21 result, the 45.3-versus-1.9-minute result, and the higher reported sexual desire. The 2000 IJIR abstract confirms the same group reviewing a pooled 20-man dataset, the sum of the 2 trials' subjects, so it is treated as a restatement rather than a third independent line of evidence. Amount and per-use figures reported in all 3 abstracts are deliberately not carried into this finding.

2. Studied for

   Pigmentation and the first human pilot trial

   The first published human trial of Melanotan-II tested it in exactly 3 healthy male volunteers, using a single-blind design that alternated Melanotan-II and saline placebo on an escalating schedule over 2 weeks. 2 of the 3 subjects showed increased pigmentation of the face, upper body and buttock, measured both by a reflectance instrument and by visual assessment, a week after the schedule ended; this is the origin of this compound's reputation as a tanning peptide. The same small trial is also the origin of the classic Melanotan-II side-effect profile: mild nausea at most levels tested, a stretching-and-yawning complex tied to the onset of spontaneous, unstimulated penile erections lasting 1 to 5 hours, and, at the highest level tested, marked drowsiness and fatigue in 1 of 2 subjects. This is real primary human data for Melanotan-II itself, not a related molecule, but the sample is 3 people, so it is read as an early pilot rather than a settled result. HUMAN a single-blind, alternating-day, placebo-controlled pilot human trial in 3 healthy male volunteers, subcutaneous use on an escalating schedule over 2 weeks Preclinical moderate A well-described result with several independent outcome measures, but from a single laboratory, a single small trial, or a single research program. Open for the full finding and the paper it came from.

   In the literature

   Pigmentation and the first human pilot trial

   The first published human trial of Melanotan-II tested it in exactly 3 healthy male volunteers, using a single-blind design that alternated Melanotan-II and saline placebo on an escalating schedule over 2 weeks. 2 of the 3 subjects showed increased pigmentation of the face, upper body and buttock, measured both by a reflectance instrument and by visual assessment, a week after the schedule ended; this is the origin of this compound's reputation as a tanning peptide. The same small trial is also the origin of the classic Melanotan-II side-effect profile: mild nausea at most levels tested, a stretching-and-yawning complex tied to the onset of spontaneous, unstimulated penile erections lasting 1 to 5 hours, and, at the highest level tested, marked drowsiness and fatigue in 1 of 2 subjects. This is real primary human data for Melanotan-II itself, not a related molecule, but the sample is 3 people, so it is read as an early pilot rather than a settled result.^{References 4}

   Modela single-blind, alternating-day, placebo-controlled pilot human trial in 3 healthy male volunteers, subcutaneous use on an escalating schedule over 2 weeks

   Confidence: moderate

   A well-described result with several independent outcome measures, but from a single laboratory, a single small trial, or a single research program.

   Source

   Dorr RT, Lines R, Levine N, Brooks C, Xiang L, Hruby VJ, Hadley ME. Evaluation of melanotan-II, a superpotent cyclic melanotropic peptide in a pilot phase-I clinical study. Life Sci. 1996;58(20):1777-1784. DOI 10.1016/0024-3205(96)00160-9. PMID 8637402.

   PubMed 8637402

   How this citation was checked

   Re-resolved live via PubMed and Crossref, exact match on title, all 7 authors, Life Sciences 1996, volume 58, issue 20, pages 1777 to 1784. The abstract confirms the single-blind alternating-day design in 3 normal male volunteers, the pigmentation result in 2 of 3 subjects a week after the schedule ended, the highest-level drowsiness and fatigue in 1 of 2 subjects, the nausea, and the stretching-and-yawning complex tied to spontaneous erections lasting 1 to 5 hours. Amount figures reported in the abstract are deliberately not carried into this finding beyond noting the schedule was escalating.

3. Studied for

   Central appetite suppression (animal mechanism)

   In a landmark 1997 mouse study that helped establish how the brain's melanocortin system controls hunger, researchers gave MTII directly into the brain's ventricles and found it suppressed feeding across 4 different mouse models of overeating: fasted normal mice, 2 genetically obese strains, and mice given neuropeptide Y to induce hunger. Giving a melanocortin-receptor blocker at the same time completely reversed the effect, showing the suppression worked through the melanocortin receptors themselves rather than some side effect. A separate 2015 study in rats, using the same direct-brain route, found the size of the feeding-suppression response to MTII depended on what the rats had been eating: rats kept on a free-choice high-fat diet showed a larger drop in food intake after MTII than rats on standard chow or high-sugar diets, an effect the authors linked to dietary fat content rather than how overweight the animals were. A third study, in female mice with excess androgen, found MTII's usual ability to suppress body weight failed in that specific hormonal context, showing the effect is not universal across physiological states. All of this is animal pharmacology: direct-brain-ventricle delivery, an experimental route rather than a usage instruction, confirmed for the Fan 1997 and van den Heuvel 2015 studies specifically, while the Nohara 2014 abstract does not state MTII's route. No human food-intake trial of Melanotan-II was located in this pass. mice and rats; direct brain-ventricle delivery confirmed for the Fan 1997 and van den Heuvel 2015 studies specifically, route not stated in the Nohara 2014 abstract Preclinical moderate A well-described result with several independent outcome measures, but from a single laboratory, a single small trial, or a single research program. Open for the full finding and the paper it came from.

   In the literature

   Central appetite suppression (animal mechanism)

   In a landmark 1997 mouse study that helped establish how the brain's melanocortin system controls hunger, researchers gave MTII directly into the brain's ventricles and found it suppressed feeding across 4 different mouse models of overeating: fasted normal mice, 2 genetically obese strains, and mice given neuropeptide Y to induce hunger. Giving a melanocortin-receptor blocker at the same time completely reversed the effect, showing the suppression worked through the melanocortin receptors themselves rather than some side effect. A separate 2015 study in rats, using the same direct-brain route, found the size of the feeding-suppression response to MTII depended on what the rats had been eating: rats kept on a free-choice high-fat diet showed a larger drop in food intake after MTII than rats on standard chow or high-sugar diets, an effect the authors linked to dietary fat content rather than how overweight the animals were. A third study, in female mice with excess androgen, found MTII's usual ability to suppress body weight failed in that specific hormonal context, showing the effect is not universal across physiological states. All of this is animal pharmacology: direct-brain-ventricle delivery, an experimental route rather than a usage instruction, confirmed for the Fan 1997 and van den Heuvel 2015 studies specifically, while the Nohara 2014 abstract does not state MTII's route. No human food-intake trial of Melanotan-II was located in this pass.^{References 5, 6, 7}

   Modelmice and rats; direct brain-ventricle delivery confirmed for the Fan 1997 and van den Heuvel 2015 studies specifically, route not stated in the Nohara 2014 abstract

   Confidence: moderate

   A well-described result with several independent outcome measures, but from a single laboratory, a single small trial, or a single research program.

   Source

   Fan W, Boston BA, Kesterson RA, Hruby VJ, Cone RD. Role of melanocortinergic neurons in feeding and the agouti obesity syndrome. Nature. 1997;385(6612):165-168. DOI 10.1038/385165a0. PMID 8990120. van den Heuvel JK, Eggels L, van Rozen AJ, Fliers E, Kalsbeek A, Adan RA, la Fleur SE. Inhibitory Effect of the Melanocortin Receptor Agonist Melanotan-II (MTII) on Feeding Depends on Dietary Fat Content and not Obesity in Rats on Free-Choice Diets. Front Behav Neurosci. 2015;9:358. DOI 10.3389/fnbeh.2015.00358. PMID 26733840. Nohara K, Laque A, Allard C, Munzberg H, Mauvais-Jarvis F. Central mechanisms of adiposity in adult female mice with androgen excess. Obesity (Silver Spring). 2014;22(6):1477-1484. DOI 10.1002/oby.20719. PMID 24639082.

   PubMed 8990120 PubMed 26733840 PubMed 24639082

   How this citation was checked

   All 3 re-resolved live via PubMed and Crossref, exact match on title, authors, journal, year, volume, issue and pages. The Fan 1997 abstract confirms feeding inhibition across the 4 named models and that a melanocortin antagonist completely blocked the inhibition. The van den Heuvel 2015 abstract confirms the lateral-ventricle route and that the effect tracked dietary fat content rather than obesity. The Nohara 2014 abstract confirms a failure of MTII to suppress body weight in the androgen-excess model. A dedicated PubMed search for Melanotan II and appetite or food intake, run in this pass, returned 79 results; none reported a human food-intake or weight trial naming Melanotan-II specifically.

4. Studied for

   Molecular design and non-selective receptor pharmacology

   The specific ring-closed structure that became Melanotan-II traces to a 1989 medicinal chemistry paper that systematically tested cyclic, lactam-bridged versions of alpha-MSH's active core in frog and lizard skin-darkening bioassays, looking for a shape that would hold its potency longer than the natural hormone. One of the 7 cyclic analogues made in that paper is an exact structural match for what would later be sold as Melanotan-II, and showed markedly higher potency than natural alpha-MSH in the lizard skin assay; the paper does not yet use the name Melanotan-II. A 2024 review of standard tool compounds for the melanocortin receptor family describes Melanotan-II, alongside afamelanotide and an antagonist compound, as one of a small set of reference molecules that shaped the field's understanding of these receptors and now serves as a scaffold for FDA-approved drugs, a description consistent with Melanotan-II's structural relationship to bremelanotide (see molecular_facts). Independent sources elsewhere in this dossier separately describe Melanotan-II as a non-selective melanocortin-receptor agonist, meaning it activates several of the 5 melanocortin receptor subtypes at once rather than being narrowly selective. That non-selectivity is the same underlying reason the compound produces effects on skin, the brain's appetite circuits and sexual response together rather than through any single pathway alone. structure-activity relationship studies in frog and lizard skin bioassays (1989 design paper), plus a later narrative review of receptor pharmacology Preclinical moderate A well-described result with several independent outcome measures, but from a single laboratory, a single small trial, or a single research program. Open for the full finding and the paper it came from.

   In the literature

   Molecular design and non-selective receptor pharmacology

   The specific ring-closed structure that became Melanotan-II traces to a 1989 medicinal chemistry paper that systematically tested cyclic, lactam-bridged versions of alpha-MSH's active core in frog and lizard skin-darkening bioassays, looking for a shape that would hold its potency longer than the natural hormone. One of the 7 cyclic analogues made in that paper is an exact structural match for what would later be sold as Melanotan-II, and showed markedly higher potency than natural alpha-MSH in the lizard skin assay; the paper does not yet use the name Melanotan-II. A 2024 review of standard tool compounds for the melanocortin receptor family describes Melanotan-II, alongside afamelanotide and an antagonist compound, as one of a small set of reference molecules that shaped the field's understanding of these receptors and now serves as a scaffold for FDA-approved drugs, a description consistent with Melanotan-II's structural relationship to bremelanotide (see molecular_facts). Independent sources elsewhere in this dossier separately describe Melanotan-II as a non-selective melanocortin-receptor agonist, meaning it activates several of the 5 melanocortin receptor subtypes at once rather than being narrowly selective. That non-selectivity is the same underlying reason the compound produces effects on skin, the brain's appetite circuits and sexual response together rather than through any single pathway alone.^{References 8, 9}

   Modelstructure-activity relationship studies in frog and lizard skin bioassays (1989 design paper), plus a later narrative review of receptor pharmacology

   Confidence: moderate

   A well-described result with several independent outcome measures, but from a single laboratory, a single small trial, or a single research program.

   Source

   Al-Obeidi F, Castrucci AM, Hadley ME, Hruby VJ. Potent and prolonged acting cyclic lactam analogues of alpha-melanotropin: design based on molecular dynamics. J Med Chem. 1989;32(12):2555-2561. DOI 10.1021/jm00132a010. PMID 2555512. Weirath NA, Haskell-Luevano C. Recommended Tool Compounds for the Melanocortin Receptor (MCR) G Protein-Coupled Receptors (GPCRs). ACS Pharmacol Transl Sci. 2024;7(9):2706-2724. DOI 10.1021/acsptsci.4c00129. PMID 39296259.

   PubMed 2555512 PubMed 39296259

   How this citation was checked

   Both re-resolved live via PubMed and Crossref, exact match on title, authors, journal, year, volume, issue, pages. The Al-Obeidi 1989 abstract lists the exact structural match among its 7 tested cyclic peptides and does not use the name Melanotan-II, consistent with that name appearing in print for the first time in the 1996 Dorr pilot trial. The Weirath 2024 abstract confirms, verbatim, that Melanotan II is one of a suite of ligands that 'serves as scaffolds for FDA-approved drugs.' The 'non-selective melanocortin-receptor agonist' phrase is independently verified verbatim in 2 separate case-report abstracts read in full elsewhere in this dossier. A relative-potency figure from the 1989 lizard-skin bioassay is deliberately not carried into this finding, to avoid it being read alongside an unrelated, unsupported vendor potency claim addressed in cannot_support.

5. Studied for

   What's actually in the vial: analytical testing of the unregulated market

   2 independent forensic and analytical chemistry teams have directly tested what unregulated Melanotan-II products actually contain. A 2015 Danish study bought vials labeled as containing 10 mg of Melanotan-II from 3 online shops and measured them by LC-UV and tandem mass spectrometry: vials from 2 of the 3 shops contained unidentified impurities of 4.1% to 5.9%, and actual Melanotan-II content across the purchased vials ranged from 4.32 mg to 8.84 mg, meaning some vials held well under half of what the label claimed. A 2021 Italian forensic toxicology study used high-resolution mass spectrometry to characterize Melanotan-II and bremelanotide separately in 8 unlabeled samples seized by police alongside anabolic steroids and other performance and image-enhancing drugs, confirming the 2 peptides are analytically distinguishable compounds rather than the same substance sold under 2 names. Together these findings describe the real, tested contents of the unregulated market this compound is sold into, not the biological action of Melanotan-II itself. analytical chemistry (LC-UV, tandem mass spectrometry, high-resolution mass spectrometry) applied to vials and seized samples purchased or confiscated from the unregulated market Preclinical moderate A well-described result with several independent outcome measures, but from a single laboratory, a single small trial, or a single research program. Open for the full finding and the paper it came from.

   In the literature

   What's actually in the vial: analytical testing of the unregulated market

   2 independent forensic and analytical chemistry teams have directly tested what unregulated Melanotan-II products actually contain. A 2015 Danish study bought vials labeled as containing 10 mg of Melanotan-II from 3 online shops and measured them by LC-UV and tandem mass spectrometry: vials from 2 of the 3 shops contained unidentified impurities of 4.1% to 5.9%, and actual Melanotan-II content across the purchased vials ranged from 4.32 mg to 8.84 mg, meaning some vials held well under half of what the label claimed. A 2021 Italian forensic toxicology study used high-resolution mass spectrometry to characterize Melanotan-II and bremelanotide separately in 8 unlabeled samples seized by police alongside anabolic steroids and other performance and image-enhancing drugs, confirming the 2 peptides are analytically distinguishable compounds rather than the same substance sold under 2 names. Together these findings describe the real, tested contents of the unregulated market this compound is sold into, not the biological action of Melanotan-II itself.^{References 10, 11}

   Modelanalytical chemistry (LC-UV, tandem mass spectrometry, high-resolution mass spectrometry) applied to vials and seized samples purchased or confiscated from the unregulated market

   Confidence: moderate

   A well-described result with several independent outcome measures, but from a single laboratory, a single small trial, or a single research program.

   Source

   Breindahl T, Evans-Brown M, Hindersson P, McVeigh J, Bellis M, Stensballe A, Kimergard A. Identification and characterization by LC-UV-MS/MS of melanotan II skin-tanning products sold illegally on the Internet. Drug Test Anal. 2015;7(2):164-172. DOI 10.1002/dta.1655. PMID 24771717. Mestria S, Odoardi S, Frison G, Strano Rossi S. LC-HRMS characterization of the skin pigmentation and sexual enhancers melanotan II and bremelanotide sold on the black market of performance and image enhancing drugs. Drug Test Anal. 2021;13(4):876-882. DOI 10.1002/dta.2986. PMID 33245851.

   PubMed 24771717 PubMed 33245851

   How this citation was checked

   Both re-resolved live via PubMed and Crossref, exact match on title, authors, journal, year, volume, issue, pages. The Breindahl 2015 abstract confirms the 3-shop purchase, the 4.1% to 5.9% impurity range in 2 of the 3 shops' vials, and the 4.32 to 8.84 mg actual-content range against a labeled 10 mg. The Mestria 2021 abstract confirms the 8 police-seized samples characterized alongside anabolic steroids and other performance-enhancing substances, with Melanotan-II and bremelanotide treated as separately characterized analytes throughout.

6. Studied for

   Acute systemic toxicity: rhabdomyolysis and kidney injury

   A 2012 emergency-medicine case report describes a 39-year-old man who took a subcutaneous amount of Melanotan-II several times his usual starting amount and presented within hours with body aches, sweating, anxiety, a fast heart rate peaking at 146 beats per minute, dilated pupils and muscle tremors. His creatine kinase, a marker of muscle breakdown, was 1,760 IU/L on arrival and rose to 17,773 IU/L over the following 12 hours; his creatinine also rose, and his urine showed blood with red cell casts. He was managed in an intensive care unit with intravenous fluids and sodium bicarbonate for rhabdomyolysis, improving over 3 days. The substance he had used was confirmed by mass spectrometry against an industry reference standard to actually be Melanotan-II; his urine drug screen was also positive for opiates, a confound the case report itself does not resolve. A separate 2020 nephrology case report and literature review describes a case of renal infarction, a blockage of blood flow to part of the kidney, attributed by the authors to Melanotan-II use through a proposed clotting or direct toxic mechanism distinct from rhabdomyolysis-driven kidney injury; that paper cites the 2012 case above as prior literature. Both are single-case reports; neither establishes how often these events occur among people who use Melanotan-II generally. 2 independent single-case reports (emergency medicine and nephrology) Preclinical preliminary A single study, a single case report, or a result whose interpretation is the authors' own inference; several harm reports on this page are rated preliminary for exactly this reason, which describes the evidentiary design, not the seriousness of what happened. Open for the full finding and the paper it came from.

   In the literature

   Acute systemic toxicity: rhabdomyolysis and kidney injury

   A 2012 emergency-medicine case report describes a 39-year-old man who took a subcutaneous amount of Melanotan-II several times his usual starting amount and presented within hours with body aches, sweating, anxiety, a fast heart rate peaking at 146 beats per minute, dilated pupils and muscle tremors. His creatine kinase, a marker of muscle breakdown, was 1,760 IU/L on arrival and rose to 17,773 IU/L over the following 12 hours; his creatinine also rose, and his urine showed blood with red cell casts. He was managed in an intensive care unit with intravenous fluids and sodium bicarbonate for rhabdomyolysis, improving over 3 days. The substance he had used was confirmed by mass spectrometry against an industry reference standard to actually be Melanotan-II; his urine drug screen was also positive for opiates, a confound the case report itself does not resolve. A separate 2020 nephrology case report and literature review describes a case of renal infarction, a blockage of blood flow to part of the kidney, attributed by the authors to Melanotan-II use through a proposed clotting or direct toxic mechanism distinct from rhabdomyolysis-driven kidney injury; that paper cites the 2012 case above as prior literature. Both are single-case reports; neither establishes how often these events occur among people who use Melanotan-II generally.^{References 12, 13}

   Model2 independent single-case reports (emergency medicine and nephrology)

   Confidence: preliminary

   A single study, a single case report, or a result whose interpretation is the authors' own inference; several harm reports on this page are rated preliminary for exactly this reason, which describes the evidentiary design, not the seriousness of what happened.

   Source

   Nelson ME, Bryant SM, Aks SE. Melanotan II injection resulting in systemic toxicity and rhabdomyolysis. Clin Toxicol (Phila). 2012;50(10):1169-1173. DOI 10.3109/15563650.2012.740637. PMID 23121206. Peters B, Hadimeri H, Wahlberg R, Afghahi H. Melanotan II: a possible cause of renal infarction: review of the literature and case report. CEN Case Rep. 2020;9(2):159-161. DOI 10.1007/s13730-020-00447-z. PMID 31953620.

   PubMed 23121206 PubMed 31953620

   How this citation was checked

   Both re-resolved live via PubMed and Crossref, exact match on title, authors, journal, year, volume, issue, pages. The Nelson 2012 abstract confirms the 39-year-old man, the vital signs and pupil and tremor findings, the creatine kinase values (1,760 rising to 17,773 IU/L), the red-cell-cast urinalysis, the opiate-positive urine drug screen, and confirmation by mass spectrometry against a reference standard. The Peters 2020 abstract confirms the renal infarction attribution and its citation of the 2012 case as prior literature.

7. Studied for

   Priapism

   At least 3 published case reports describe priapism, a painful erection lasting well beyond ordinary sexual response, after Melanotan-II use. The earliest, a 2013 letter to the editor responding to the rhabdomyolysis case above, describes a case of priapism following Melanotan-II use well beyond typical amounts; PubMed carries no abstract for this letter, so beyond its title and its status as an early published instance, no further clinical detail from it is stated here. A 2019 case report describes a man who developed acute low-flow priapism after abdominal subcutaneous use of melanotan, managed with cavernosal aspiration, irrigation and intracavernosal phenylephrine, avoiding surgery but not having recovered erectile function at 4-week follow-up. A 2021 case report describes a man with acute ischemic priapism after subcutaneous Melanotan-II use whose conservative management failed, requiring operative penoscrotal decompression; that paper states priapism after Melanotan-II had, to its authors' knowledge, been reported in the literature only twice before. Read together, the pattern across these reports is that Melanotan-II-associated priapism is not self-limiting in every case, with outcomes ranging from unresolved erectile function at 1 month to a surgical emergency. 3 independent single-case reports, 1 available as title and metadata only Preclinical preliminary A single study, a single case report, or a result whose interpretation is the authors' own inference; several harm reports on this page are rated preliminary for exactly this reason, which describes the evidentiary design, not the seriousness of what happened. Open for the full finding and the paper it came from.

   In the literature

   Priapism

   At least 3 published case reports describe priapism, a painful erection lasting well beyond ordinary sexual response, after Melanotan-II use. The earliest, a 2013 letter to the editor responding to the rhabdomyolysis case above, describes a case of priapism following Melanotan-II use well beyond typical amounts; PubMed carries no abstract for this letter, so beyond its title and its status as an early published instance, no further clinical detail from it is stated here. A 2019 case report describes a man who developed acute low-flow priapism after abdominal subcutaneous use of melanotan, managed with cavernosal aspiration, irrigation and intracavernosal phenylephrine, avoiding surgery but not having recovered erectile function at 4-week follow-up. A 2021 case report describes a man with acute ischemic priapism after subcutaneous Melanotan-II use whose conservative management failed, requiring operative penoscrotal decompression; that paper states priapism after Melanotan-II had, to its authors' knowledge, been reported in the literature only twice before. Read together, the pattern across these reports is that Melanotan-II-associated priapism is not self-limiting in every case, with outcomes ranging from unresolved erectile function at 1 month to a surgical emergency.^{References 14, 15, 16}

   Model3 independent single-case reports, 1 available as title and metadata only

   Confidence: preliminary

   A single study, a single case report, or a result whose interpretation is the authors' own inference; several harm reports on this page are rated preliminary for exactly this reason, which describes the evidentiary design, not the seriousness of what happened.

   Source

   Devlin J, Pomerleau A, Foote J. Melanotan II overdose associated with priapism. Clin Toxicol (Phila). 2013;51(4):383. DOI 10.3109/15563650.2013.784775. PMID 23537392. Dreyer BA, Amer T, Fraser M. Melanotan-induced priapism: a hard-earned tan. BMJ Case Rep. 2019;12(2):e227644. DOI 10.1136/bcr-2018-227644. PMID 30796078. Mallory CW, Lopategui DM, Cordon BH. Melanotan Tanning Injection: A Rare Cause of Priapism. Sex Med. 2021;9(1):100298. DOI 10.1016/j.esxm.2020.100298. PMID 33460908.

   PubMed 23537392 PubMed 30796078 PubMed 33460908

   How this citation was checked

   All 3 re-resolved live via PubMed and Crossref, exact match on title, authors, journal, year, volume/issue/page. The Devlin 2013 PubMed record returns only a title, author list and a 'comment on' link to the Nelson 2012 paper, with no abstract in PubMed or Europe PMC; an attempt to retrieve the free PDF returned an access-denied response, so no clinical detail beyond the title is asserted for this citation. The Dreyer 2019 abstract confirms the abdominal subcutaneous route, the cavernosal aspiration, irrigation and intracavernosal phenylephrine management, and the unrecovered erectile function at 4-week follow-up. The Mallory 2021 abstract confirms the acute ischemic priapism, the failed conservative management, the operative penoscrotal decompression, and the authors' statement that priapism after Melanotan-II had been reported only twice before.

8. Studied for

   Melanocytic lesion changes and melanoma

   A 2017 dermatology review states that a growing number of case reports link unregulated use of both afamelanotide and Melanotan-II to skin complications, particularly changes in existing moles and newly emerging moles, and that several case reports at the time described melanoma emerging from existing moles during or shortly after melanotan use, while noting that conclusive evidence linking these events is lacking even as multiple national health organizations had issued safety warnings. Individual case reports since then and before it, several verified here only at the title-and-metadata level because they carry no indexed abstract, describe: a 20-year-old woman whose melanoma was diagnosed 3 months after a several-week course of self-directed Melanotan-II use alongside sunbed tanning; a UK report of newly emerging moles following melanotan use; a Belgian report of melanoma associated with melanotan use; a 2026 report of a man with brown pigmentation of the gums and inner cheeks after several weeks of self-directed Melanotan-II use, which faded over the following months after he stopped; and a 2026 report of 5 separate melanomas in situ in a 49-year-old man who had used tanning beds, Melanotan-II followed by Melanotan-I, and testosterone at the same time, in which the authors state plainly that causality could not be established and call tanning-bed use a well-established and likely significant independent risk factor for melanoma and a major confounding variable, while listing testosterone as a further possible confounder and noting the short melanotan exposure window raised the possibility the lesions were already present and only became visible rather than newly forming. No case report located in this pass isolates Melanotan-II as the sole exposure; every detailed report available in full names at least 1 other tanning or hormonal exposure at the same time. a 2017 review plus individual case reports, 2009 to 2026, multiple countries, several accessible only as verified titles Preclinical preliminary A single study, a single case report, or a result whose interpretation is the authors' own inference; several harm reports on this page are rated preliminary for exactly this reason, which describes the evidentiary design, not the seriousness of what happened. Open for the full finding and the paper it came from.

   In the literature

   Melanocytic lesion changes and melanoma

   A 2017 dermatology review states that a growing number of case reports link unregulated use of both afamelanotide and Melanotan-II to skin complications, particularly changes in existing moles and newly emerging moles, and that several case reports at the time described melanoma emerging from existing moles during or shortly after melanotan use, while noting that conclusive evidence linking these events is lacking even as multiple national health organizations had issued safety warnings. Individual case reports since then and before it, several verified here only at the title-and-metadata level because they carry no indexed abstract, describe: a 20-year-old woman whose melanoma was diagnosed 3 months after a several-week course of self-directed Melanotan-II use alongside sunbed tanning; a UK report of newly emerging moles following melanotan use; a Belgian report of melanoma associated with melanotan use; a 2026 report of a man with brown pigmentation of the gums and inner cheeks after several weeks of self-directed Melanotan-II use, which faded over the following months after he stopped; and a 2026 report of 5 separate melanomas in situ in a 49-year-old man who had used tanning beds, Melanotan-II followed by Melanotan-I, and testosterone at the same time, in which the authors state plainly that causality could not be established and call tanning-bed use a well-established and likely significant independent risk factor for melanoma and a major confounding variable, while listing testosterone as a further possible confounder and noting the short melanotan exposure window raised the possibility the lesions were already present and only became visible rather than newly forming. No case report located in this pass isolates Melanotan-II as the sole exposure; every detailed report available in full names at least 1 other tanning or hormonal exposure at the same time.^{References 17, 18, 19, 20, 21, 22}

   Modela 2017 review plus individual case reports, 2009 to 2026, multiple countries, several accessible only as verified titles

   Confidence: preliminary

   A single study, a single case report, or a result whose interpretation is the authors' own inference; several harm reports on this page are rated preliminary for exactly this reason, which describes the evidentiary design, not the seriousness of what happened.

   Source

   Habbema L, Halk AB, Neumann M, Bergman W. Risks of unregulated use of alpha-melanocyte-stimulating hormone analogues: a review. Int J Dermatol. 2017;56(10):975-980. DOI 10.1111/ijd.13585. PMID 28266027. Hjuler KF, Lorentzen HF. Melanoma associated with the use of melanotan-II. Dermatology. 2014;228(1):34-36. DOI 10.1159/000356389. PMID 24355990. Cousen P, Colver G, Helbling I. Eruptive melanocytic naevi following melanotan injection. Br J Dermatol. 2009;161(3):707-708. DOI 10.1111/j.1365-2133.2009.09362.x. PMID 19575725. Paurobally D, Jason F, Dezfoulian B, Nikkels AF. Melanotan-associated melanoma. Br J Dermatol. 2011;164(6):1403-1405. DOI 10.1111/j.1365-2133.2011.10273.x. PMID 21564053. Bonchev A. Changes in Oral Mucosa Associated with Melanotan II Injections: A Case Report. Life (Basel). 2026;16(2):265. DOI 10.3390/life16020265. PMID 41752902. Vadner DJ, Smith S. Five primary melanomas in situ in a patient with recent tanning bed use, melanotan exposure, and anabolic hormone use. JAAD Case Rep. 2026;73:111-114. DOI 10.1016/j.jdcr.2026.05.009. PMID 42328529.

   PubMed 28266027 PubMed 24355990 PubMed 19575725 PubMed 21564053 PubMed 41752902 PubMed 42328529

   How this citation was checked

   All 6 re-resolved live via PubMed and Crossref, exact match on title, authors, journal, year, volume/issue/page for each. The Habbema 2017 abstract confirms the review's claims verbatim as reported. The Hjuler 2014 abstract confirms the 20-year-old woman, the melanoma diagnosis timing, and the concurrent sunbed tanning. The Cousen 2009 and Paurobally 2011 PubMed records return only title, authors and journal metadata with no indexed abstract in PubMed or Europe PMC, so no clinical detail beyond title is asserted for either. The Bonchev 2026 abstract, read in full, confirms the oral pigmentation, its onset over several weeks of self-directed use, and its fading after he stopped. The Vadner 2026 record's abstract field is empty, so its full open-access text was read directly; the quotations above (the 49-year-old man, the 5-melanoma-in-situ count, and the authors' own causality discussion including the confounders named) are taken from that full text.

9. Studied for

   Female sexual behavior: animal-verified, human claim unresolved

   In ovariectomized, hormone-primed rats, intravenous Melanotan-II increased proceptive sexual behaviors, solicitations such as hops, darts and ear-wiggling, in females primed with both estrogen and progesterone, though it did not change pacing or the lordosis reflex, and had no effect in females primed with estrogen alone; the authors read this as evidence that progesterone interacts with Melanotan-II to increase solicitation behavior specifically. This is animal data. Separately, a University of Arizona investigator involved in the original human trials above later wrote, in a short first-person historical account, that Melanotan-II can enhance sexual function in human males and in females, framing the discovery as accidental during skin-pigmentation studies. That sentence is the only source located in this pass for a human female effect; no peer-reviewed trial report giving a method, a sample size or a statistical result for Melanotan-II and female sexual response in humans was found. This dossier does not carry a human female finding beyond flagging that the claim exists in the literature without a located primary trial behind it. 1 animal study (ovariectomized, hormone-primed rats, intravenous route) plus 1 first-person historical account asserting an unreferenced human female effect Preclinical preliminary A single study, a single case report, or a result whose interpretation is the authors' own inference; several harm reports on this page are rated preliminary for exactly this reason, which describes the evidentiary design, not the seriousness of what happened. Open for the full finding and the paper it came from.

   In the literature

   Female sexual behavior: animal-verified, human claim unresolved

   In ovariectomized, hormone-primed rats, intravenous Melanotan-II increased proceptive sexual behaviors, solicitations such as hops, darts and ear-wiggling, in females primed with both estrogen and progesterone, though it did not change pacing or the lordosis reflex, and had no effect in females primed with estrogen alone; the authors read this as evidence that progesterone interacts with Melanotan-II to increase solicitation behavior specifically. This is animal data. Separately, a University of Arizona investigator involved in the original human trials above later wrote, in a short first-person historical account, that Melanotan-II can enhance sexual function in human males and in females, framing the discovery as accidental during skin-pigmentation studies. That sentence is the only source located in this pass for a human female effect; no peer-reviewed trial report giving a method, a sample size or a statistical result for Melanotan-II and female sexual response in humans was found. This dossier does not carry a human female finding beyond flagging that the claim exists in the literature without a located primary trial behind it.^{References 23, 24}

   Model1 animal study (ovariectomized, hormone-primed rats, intravenous route) plus 1 first-person historical account asserting an unreferenced human female effect

   Confidence: preliminary

   A single study, a single case report, or a result whose interpretation is the authors' own inference; several harm reports on this page are rated preliminary for exactly this reason, which describes the evidentiary design, not the seriousness of what happened.

   Source

   Rossler AS, Pfaus JG, Kia HK, Bernabe J, Alexandre L, Giuliano F. The melanocortin agonist, melanotan II, enhances proceptive sexual behaviors in the female rat. Pharmacol Biochem Behav. 2006;85(3):514-521. DOI 10.1016/j.pbb.2006.09.023. PMID 17113634. Hadley ME. Discovery that a melanocortin regulates sexual functions in male and female humans. Peptides. 2005;26(10):1687-1689. DOI 10.1016/j.peptides.2005.01.023. PMID 15996790.

   PubMed 17113634 PubMed 15996790

   How this citation was checked

   Both re-resolved live via PubMed and Crossref, exact match on title, authors, journal, year, volume, issue, pages. The Rossler 2006 abstract confirms the increased hops, darts and ear-wiggling in estrogen-plus-progesterone-primed females with no effect on pacing or lordosis, and no effect in estrogen-only-primed females. The Hadley 2005 abstract, a single-author historical piece, is a direct source for the human female claim quoted above and gives no method, sample size or statistic for it; a dedicated PubMed search for Melanotan II and women, run in this pass, did not surface a distinct trial report supplying any of that.

10. Studied for

    Posterior reversible encephalopathy syndrome

    A short clinical report on Melanotan and posterior reversible encephalopathy syndrome was published in a general-medicine journal in 2013, describing a case of PRES, a syndrome of seizures, visual disturbance, confusion, headache and vomiting together with a characteristic pattern of reversible brain swelling on MRI, in the setting of melanotan use. The full text sits behind a subscription paywall; PubMed and Europe PMC both carry only the title for this record, with no indexed abstract, and a direct fetch of the publisher page returned an access-denied response. This dossier states only what is independently confirmable: the citation is real and correctly resolves in both PubMed and Crossref, it was published in a high-profile general-medicine journal, a real editorial bar for a case report to clear, and its title describes a reported case of PRES associated with melanotan use. No age, sex, amount used, timeline or outcome is stated here, because none of it was accessible in this pass. 1 case report, content inaccessible beyond title and bibliographic metadata Preclinical preliminary A single study, a single case report, or a result whose interpretation is the authors' own inference; several harm reports on this page are rated preliminary for exactly this reason, which describes the evidentiary design, not the seriousness of what happened. Open for the full finding and the paper it came from.

    In the literature

    Posterior reversible encephalopathy syndrome

    A short clinical report on Melanotan and posterior reversible encephalopathy syndrome was published in a general-medicine journal in 2013, describing a case of PRES, a syndrome of seizures, visual disturbance, confusion, headache and vomiting together with a characteristic pattern of reversible brain swelling on MRI, in the setting of melanotan use. The full text sits behind a subscription paywall; PubMed and Europe PMC both carry only the title for this record, with no indexed abstract, and a direct fetch of the publisher page returned an access-denied response. This dossier states only what is independently confirmable: the citation is real and correctly resolves in both PubMed and Crossref, it was published in a high-profile general-medicine journal, a real editorial bar for a case report to clear, and its title describes a reported case of PRES associated with melanotan use. No age, sex, amount used, timeline or outcome is stated here, because none of it was accessible in this pass.^{References 25}

    Model1 case report, content inaccessible beyond title and bibliographic metadata

    Confidence: preliminary

    A single study, a single case report, or a result whose interpretation is the authors' own inference; several harm reports on this page are rated preliminary for exactly this reason, which describes the evidentiary design, not the seriousness of what happened.

    Source

    Kaski D, Stafford N, Mehta A, Jenkins IH, Malhotra P. Melanotan and the Posterior Reversible Encephalopathy Syndrome. Ann Intern Med. 2013;158(9):707-708. DOI 10.7326/0003-4819-158-9-201305070-00020. PMID 23648958.

    PubMed 23648958

    How this citation was checked

    Re-resolved live via PubMed and Crossref, exact match on title, all 5 authors, Annals of Internal Medicine 2013, volume 158, issue 9, pages 707 to 708. Multiple attempts to reach content beyond the title (Europe PMC, a direct fetch of the journal page, a fetch of the DOI redirect target, a publisher-mirror attempt) all failed to return usable text, so this entry is deliberately limited to what the title and confirmed bibliographic record support, and that coverage limit is stated in the finding itself rather than left implicit.

1 strong / 4 moderate / 5 preliminaryRated by how many independent labs and how many kinds of experiment found the same thing.