Data edition of
Residue An evidence-graded reference for peptide science

Monograph in Melanocortin peptides

Melanotan II

A cyclic analog of α-MSH that darkens skin and triggers erections. The controlled human data are three small studies from the 1990s; most later papers are case reports of harm.

Also called MT-II · MT-2 · Melanotan 2

C

Best evidence: Limited / early human data

Two double-blind, placebo-controlled crossover studies of 10 men each and a 3-man phase I pilot; the abstracts do not report randomization. Later literature is mainly case reports.

Not FDA-approved · FDA compounding nomination withdrawn

Residue Editorial Team · updated

What is Melanotan II?

Melanotan II is a lactam-bridged cyclic heptapeptide analog of α-melanocyte-stimulating hormone1PubMedEvaluation of melanotan-II, a superpotent cyclic melanotropic peptide in a pilot phase-I clinical study. Dorr RT et al. Life Sci. 1996.. In a 1996 phase I pilot in three men it increased skin pigmentation and caused spontaneous erections1; two later 10-man crossover studies found it initiated erections in men with erectile dysfunction2PubMedSynthetic melanotropic peptide initiates erections in men with psychogenic erectile dysfunction: double-blind, placebo controlled crossover study. Wessells H et al. J Urol. 1998.,3PubMedEffect of an alpha-melanocyte stimulating hormone analog on penile erection and sexual desire in men with organic erectile dysfunction. Wessells H et al. Urology. 2000.. It is not FDA-approved, and FDA records published case reports of melanoma, priapism and sympathomimetic toxicity4FDACertain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks. U.S. FDA, content current as of 04/22/2026..

PubMed records
62533 reviews
Trial publications
51 tagged RCT
Registered studies
11 active · 0 phase 3
Molecular weight
1,024.2g/mol · PubChem
Evidence grade
CLimited / early human data

Key findings

  1. In 10 men with psychogenic erectile dysfunction, 8 developed clinically apparent erections; mean time at more than 80% tip rigidity was 38.0 minutes with MT-II versus 3.0 with placebo2.
  2. In 10 men with organic risk factors, MT-II initiated erections after 12 of 19 injections versus 1 of 21 placebo doses, and 4 of 19 injections caused severe nausea3.
  3. In a 3-man pilot, five low subcutaneous doses increased pigmentation of the face, upper body and buttock, measured by reflectance1.
  4. Case reports describe melanoma after self-injection with sunbed use5PubMedMelanoma associated with the use of melanotan-II. Hjuler KF & Lorentzen HF Dermatology. 2014., rhabdomyolysis and systemic toxicity6PubMedMelanotan II injection resulting in systemic toxicity and rhabdomyolysis. Nelson ME et al. Clin Toxicol (Phila). 2012., renal infarction7PubMedMelanotan II: a possible cause of renal infarction: review of the literature and case report. Peters B et al. CEN Case Rep. 2020. and ischemic priapism8PubMedMelanotan Tanning Injection: A Rare Cause of Priapism. Mallory CW et al. Sex Med. 2021..
  5. FDA lists Melanotan II among withdrawn compounding nominations and cites published reports of melanoma, posterior reversible encephalopathy syndrome, sympathomimetic toxidrome and priapism4.

Written by Residue Editorial Team

Reviewed by Residue Editorial Team · source-by-source check,

First published

Last updated

Registry data · How we grade · Markdown + sources

What is Melanotan II, chemically?

Identifiers retrieved from PubChem.
PubChem CID92432 “melanotan-II”
FormulaC50H69N15O9
Molecular weight1,024.2 g/mol
CAS (as listed)121062-08-6
FDA UNIIUPF5CJ93X7
InChIKeyJDKLPDJLXHXHNV-MFVUMRCOSA-N
Length7 residues
Route in trialsSubcutaneous injection (trials)
MechanismNon-selective melanocortin-receptor agonist; pigmentation via MC1R
  • Hydrophobic
  • Basic (+)
  • Acidic (−)
  • Non-standard
Figure 1. Residue sequence of Melanotan II (7 positions) as recorded in PubChem CID 92432 — Ac-Nle-Asp(1)-His-D-Phe-Arg-Trp-Lys(1)-NH2. “X” marks 1 non-standard, D-form or chemically modified position; see the condensed notation.

What is Melanotan II?

Melanotan II (MT-II) is Ac-Nle4-Asp5-His6-D-Phe7-Arg8-Trp9-Lys10 α-MSH(4-10)-NH2, a lactam-bridged cyclic heptapeptide with superpotent melanotropic activity in vitro1. PubChem lists the formula C50H69N15O99PubChemPubChem compound record: melanotan-II. C50H69N15O9 · MW 1024.2 g/mol.. It was developed as a tanning agent, and its effect on erections was noticed in the first human study1.

How is Melanotan II thought to work?

MT-II is a non-selective melanocortin-receptor agonist whose effects in humans include increased skin pigmentation, spontaneous erections and sexual stimulation7. Its pigmenting effect runs through the melanocortin 1 receptor10PubMedMelanotan II User Experience: A Qualitative Study of Online Discussion Forums. Gilhooley E et al. Dermatology. 2021.. Bremelanotide, approved for a desire disorder in women, has high affinity for the melanocortin type 4 receptor11PubMedBremelanotide: First Approval. Dhillon S & Keam SJ Drugs. 2019., and its PubChem record lists the same seven-residue sequence as MT-II12PubChemPubChem compound record: Bremelanotide. C50H68N14O10 · MW 1025.2 g/mol.,9.

What have studies found?

Tanning. The 1996 phase I pilot gave three men subcutaneous MT-II or saline on alternating weekdays for two weeks. Two showed increased pigmentation one week after dosing ended1.

Erections. In ten men with psychogenic erectile dysfunction, eight developed erections under RigiScan monitoring; tip rigidity above 80% lasted a mean of 38.0 minutes versus 3.0 on placebo (p=0.0045)2. A second ten-man study in men with organic risk factors found erections after 12 of 19 MT-II injections versus 1 of 21 placebo doses, with higher reported sexual desire3.

Unsupervised use. A qualitative study of 623 UK and Irish forum posts found MT-II used mainly for tanning before holidays and competitions, often alongside sunbeds10. ClinicalTrials.gov lists one registered study, of MT-II added to phototherapy for vitiligo13TrialClinicalTrials.gov registry search: "melanotan II" OR melanotan-II. 1 registered studies at fetch..

What are the reported harms?

Case reports include a melanoma in a 20-year-old woman after a course of self-injections with sunbed use5; rhabdomyolysis, tachycardia and kidney injury after a 6 mg injection bought online6; a renal infarction7; and ischemic priapism requiring surgery8. A 2017 review counted four case reports of melanoma arising from existing moles during or shortly after melanotan use, and notes that conclusive evidence of a link is lacking14PubMedRisks of unregulated use of alpha-melanocyte-stimulating hormone analogues: a review. Habbema L et al. Int J Dermatol. 2017.. Case reports cannot establish how often these harms occur.

Is Melanotan II FDA-approved?

Table 1. Regulatory status of Melanotan II in the United States — from Drugs@FDA (openFDA) and FDA’s bulk-substance compounding categories, as fetched.
RecordStatusSource
FDA approval No approved application Drugs@FDA returned no application for “Melanotan II”. openFDA
Compounding: nominated, then withdrawn
Melanotan II		 Withdrawn nomination FDA still lists its safety concerns:
“Compounded drugs containing Melanotan II may pose risk for immunogenicity for certain routes of administration due to the potential for aggregation or peptide-related impurities. Published case reports discuss serious adverse events including melanoma, posterior reversible encephalopathy syndrome, sympathomimetic toxidrome and priapism.”		 4

FDA lists Melanotan II among substances whose compounding nominations were withdrawn, noting immunogenicity risk and citing published case reports of melanoma, posterior reversible encephalopathy syndrome, sympathomimetic toxidrome and priapism4. Drugs@FDA returned no application for it.

What is still unknown?

  • Randomized trials of adequate size for any use; the controlled data are 23 men across three studies1,2,3.
  • Long-term skin safety, including any melanoma risk, which case reports raise but cannot measure5.

What effects has Melanotan II shown, by body system?

Each row is graded separately using the Residue evidence scale: a compound can carry an A for one use and a D for another.

Table 2. Research-observed effects of Melanotan II by body system, with the strongest evidence available for each.
SystemWhat was observedGrade
Erectile functionErections in 8 of 10 men with psychogenic ED and after 12 of 19 injections in men with organic risk factors, in placebo-controlled crossover studies2,3. C
Skin pigmentationIncreased facial and body pigmentation in a 3-man phase I pilot1. C
Sexual desireSelf-reported desire higher after MT-II than placebo in one 10-man study3. C
Adverse effectsNausea, yawning/stretching and reduced appetite in trials2; melanoma, rhabdomyolysis, renal infarction and priapism in case reports5,6,7,8. C

How much research is there on Melanotan II?

02141 1990: 5 records 1990 1991: 8 records 1992: 12 records 1993: 10 records 1994: 13 records 1995: 15 records 1995 1996: 14 records 1997: 10 records 1998: 28 records 1999: 20 records 2000: 26 records 2000 2001: 16 records 2002: 25 records 2003: 31 records 2004: 21 records 2005: 41 records 2005 2006: 28 records 2007: 34 records 2008: 26 records 2009: 19 records 2010: 22 records 2010 2011: 14 records 2012: 17 records 2013: 23 records 2014: 19 records 2015: 17 records 2015 2016: 11 records 2017: 11 records 2018: 18 records 2019: 7 records 2020: 18 records 2020 2021: 18 records 2022: 12 records 2023: 9 records 2024: 9 records 2025: 4 records 2025 2026: 7 records (year to date) 2026
Figure 2. PubMed records per publication year matching ("melanotan II"[tiab] OR "melanotan-II"[tiab] OR "melanotan 2"[tiab] OR MT-II[tiab]) — 625 in total; peak 41 in 2005. The 2026 bar is year-to-date (hatched). Volume of literature is not evidence of efficacy. Run this query on PubMed.
Registered studies of Melanotan II by phase and status
PhaseStudiesBreakdown
Phase 2 1
0 completed, 1 active or recruiting, 0 stopped, 0 other
Figure 3. 1 studies on ClinicalTrials.gov match the registry search "melanotan II" OR melanotan-II. Multi-phase studies are counted at their highest phase.

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Questions readers ask

Is Melanotan II FDA-approved?

No. FDA lists Melanotan II among bulk substances whose compounding nominations were withdrawn and records published case reports of serious adverse events4. Its relative afamelanotide is approved, as Scenesse, for a single rare disease15.

What is the difference between Melanotan 1 and Melanotan 2?

Melanotan I is afamelanotide, a linear 13-residue α-MSH analog approved as an implant for erythropoietic protoporphyria16,15. Melanotan II is a shorter cyclic analog that also caused erections in trials and was never approved1,2.

What doses of Melanotan II were used in studies?

The 1996 pilot recommended 0.025 mg/kg/day for future phase I studies1, and both erection studies used 0.025 mg/kg by subcutaneous injection2,3. These are research doses, not recommendations.

What are the side effects of Melanotan II?

In trials: nausea, stretching and yawning, decreased appetite, and in one subject grade II somnolence and fatigue1,2. Case reports describe melanoma, rhabdomyolysis, renal infarction and priapism5,6,7,8.

References

Every source below was retrieved from its official API or page and cached on the data-edition date. Numbers match the margin notes.

  1. 1 PubMed Dorr RT, Lines R, Levine N, et al. Evaluation of melanotan-II, a superpotent cyclic melanotropic peptide in a pilot phase-I clinical study. Life Sci 1996. PMID 8637402; doi:10.1016/0024-3205(96)00160-9.
  2. 2 PubMed Wessells H, Fuciarelli K, Hansen J, et al. Synthetic melanotropic peptide initiates erections in men with psychogenic erectile dysfunction: double-blind, placebo controlled crossover study. J Urol 1998. PMID 9679884.
  3. 3 PubMed Wessells H, Gralnek D, Dorr R, et al. Effect of an alpha-melanocyte stimulating hormone analog on penile erection and sexual desire in men with organic erectile dysfunction. Urology 2000. PMID 11018622; doi:10.1016/s0090-4295(00)00680-4.
  4. 4 FDA Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks. U.S. FDA, content current as of 04/22/2026.
  5. 5 PubMed Hjuler KF, Lorentzen HF. Melanoma associated with the use of melanotan-II. Dermatology 2014. PMID 24355990; doi:10.1159/000356389.
  6. 6 PubMed Nelson ME, Bryant SM, Aks SE. Melanotan II injection resulting in systemic toxicity and rhabdomyolysis. Clin Toxicol (Phila) 2012. PMID 23121206; doi:10.3109/15563650.2012.740637.
  7. 7 PubMed Peters B, Hadimeri H, Wahlberg R, et al. Melanotan II: a possible cause of renal infarction: review of the literature and case report. CEN Case Rep 2020. PMID 31953620; doi:10.1007/s13730-020-00447-z.
  8. 8 PubMed Mallory CW, Lopategui DM, Cordon BH. Melanotan Tanning Injection: A Rare Cause of Priapism. Sex Med 2021. PMID 33460908; doi:10.1016/j.esxm.2020.100298.
  9. 9 PubChem PubChem compound record: melanotan-II. C50H69N15O9 · MW 1024.2 g/mol.
  10. 10 PubMed Gilhooley E, Daly S, McKenna D. Melanotan II User Experience: A Qualitative Study of Online Discussion Forums. Dermatology 2021. PMID 34464955; doi:10.1159/000514492.
  11. 11 PubMed Dhillon S, Keam SJ. Bremelanotide: First Approval. Drugs 2019. PMID 31429064; doi:10.1007/s40265-019-01187-w.
  12. 12 PubChem PubChem compound record: Bremelanotide. C50H68N14O10 · MW 1025.2 g/mol.
  13. 13 ClinicalTrials.gov ClinicalTrials.gov registry search: "melanotan II" OR melanotan-II. 1 registered studies at fetch.
  14. 14 PubMed Habbema L, Halk AB, Neumann M, et al. Risks of unregulated use of alpha-melanocyte-stimulating hormone analogues: a review. Int J Dermatol 2017. PMID 28266027; doi:10.1111/ijd.13585.
  15. 15 FDA Drugs@FDA: SCENESSE (NDA210797). CLIVUNEL INC; original approval 2019-10-08; Prescription.
  16. 16 PubChem PubChem compound record: Afamelanotide. C78H111N21O19 · MW 1646.8 g/mol.