Skip to content
Peptide Spencer
Partner

Reproductive & melanocortin

Melanotan II

Also known as MT-II, MT2, Melanotan-II, Ac-Nle4-Asp5-His6-D-Phe7-Arg8-Trp9-Lys10-NH2 (cyclic)

Limited human data

Synthetic cyclic non-selective melanocortin receptor agonist (alpha-MSH analog)

Not FDA-approved. Not on FDA's 503A category lists (May 14, 2026). Source, May 14, 2026

Identity. Melanotan II (MT-II) is a cyclic lactam-bridged heptapeptide analog of alpha-MSH described by Dorr 1996 (Ac-Nle4-Asp5-His6-D-Phe7-Arg8-Trp9-Lys10 alpha-MSH4-10-NH2). It differs from Melanotan I (afamelanotide, [Nle4-D-Phe7]-alpha-MSH) and from bremelanotide, a variation of MT-II designed for sexual stimulation (Nelson 2012). A product label that reads only 'Melanotan' could mean MT-I or MT-II. Confirm the sequence and CAS number on the certificate of analysis.

At a glance

These dosages are a helpful guide, not a prescription. Every clinician is expected to do their own due diligence before prescribing.

  1. Start

    0.01 mg/kg per dose subcutaneous, escalated in 0.005 mg/kg increments1

    Human study

  2. Typical

    0.025 mg/kg subcutaneous as a single dose23

    Human study

  3. Ceiling

    0.025 mg/kg SC per dose recommended; 0.03 mg/kg caused Grade II somnolence1

    Human study
Frequency
Every other day, alternating with saline, in the phase I pilot1
Route
Subcutaneous injection12
Course
2 consecutive weeks (about 5 MT-II doses) in the phase I pilot1
Doses are mg/kg per injection from small male studies only; do not read 0.025 mg/kg as a flat 0.025 mg.
Calculate this dose

Dosing detail

Human studies

Human study

  • Phase I pilot, 3 normal male volunteers, tanning/tolerability; alternating-day saline or MT-II, placebo-controlled, single-blind

    0.01 starting dose; escalated in 0.005 increments to 0.03 (two subjects) or 0.025 (one subject) mg/kg1

    Route
    subcutaneous
    Frequency
    MT-II every other day, alternating with saline, within a Monday-Friday dosing schedule; about 5 MT-II doses over 2 weeks (not daily MT-II)
    Duration
    2 consecutive weeks
    n
    3
    Design
    single-blind, alternating-day, placebo-controlled pilot phase I
    Source quote
    A single-blind, alternating day (saline or MT-II), placebo-controlled trial was conducted in 3 normal male volunteers at the starting dose of 0.01 mg/kg of MT-II. Two subjects were escalated by 0.005 mg/kg increments to 0.03 mg/kg and one to 0.025 mg/kg. These results demonstrate that MT-II has tanning activity in humans given only 5 low doses every other day by subcutaneous injection.

    Finding. 0.03 mg/kg caused Grade II somnolence/fatigue in 1 of 2 subjects. Nausea, stretching/yawning, erections, and increased pigmentation also occurred. The authors recommended 0.025 mg/kg as the single MT-II dose (written as '0.025 mg/kg/day' in the paper) for future phase I studies.

  • Men with psychogenic erectile dysfunction; double-blind placebo-controlled crossover; erections monitored by RigiScan for 6 hours

    0.025 mg/kg3

    Route
    subcutaneous per PubMed MeSH indexing ('Injections, Subcutaneous'); the abstract does not state the route and full text was not reviewed
    Frequency
    single dose per monitored session (double-blind crossover); schedule not stated in abstract
    Duration
    6-hour monitoring period per session
    n
    10
    Design
    double-blind, placebo-controlled crossover
    Source quote
    Melanotan-II is a potent initiator of erections in men with psychogenic erectile dysfunction and has manageable side effects at a dose of 0.025 mg./kg.

    Finding. 8 of 10 men developed clinically apparent erections. Mean tip rigidity >80% lasted 38.0 min with MT-II vs 3.0 min with placebo (p=0.0045). Nausea, stretching/yawning, and decreased appetite were reported.

  • Men with erectile dysfunction and organic risk factors; double-blind placebo-controlled crossover

    0.025 mg/kg2

    Route
    subcutaneous injection
    Frequency
    MT-II and vehicle each administered twice (single doses in separate monitored sessions)
    Duration
    6-hour monitoring per injection
    n
    10
    Design
    randomized double-blind placebo-controlled crossover
    Source quote
    Ten subjects were enrolled in a double-blind, placebo-controlled, crossover study. 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.

    Finding. Erections were reported after 12 of 19 MT-II injections vs 1 of 21 placebo doses. 4 of 19 MT-II injections were associated with severe nausea.

  • Pooled review of the group's own experience in men with psychogenic and organic ED. It is not an independent cohort, and its 20 men almost certainly overlap the two n=10 studies above

    0.025 mg/kg4

    Route
    not stated in abstract (likely subcutaneous as in the companion studies; unconfirmed)
    Frequency
    single dose per monitored session (crossover); not stated in abstract
    Duration
    6 h penile rigidity monitoring
    n
    20 (pooled review; not additional subjects)
    Design
    double-blind placebo-controlled crossover (review of the group's own studies; likely pools the n=10 and n=10 cohorts)
    Source quote
    Melanotan II was administered to 20 men with psychogenic and organic ED using a double-blind placebo-controlled crossover design. Penile rigidity was monitored for 6 h using RigiScan. [...] Nausea and yawning were frequently reported side effects due to Melanotan II; at a dose of 0.025 mg/kg, 12.9% of subjects had severe nausea.

    Finding. Erection in 17 of 20 men, with mean tip rigidity >80% lasting 41 min. At 0.025 mg/kg, 12.9% of subjects had severe nausea.

Clinical practice

Clinical practice

No credible practice source with milligram amounts is available. Commercial pages that offer flat milligram starting doses and titration conflict with each other (for example, a 0.25 mg start vs 1-2 mg daily loading), so none are used. The only practice-level statement is the route, from a patient-education page (DermNet NZ, 2015). The only human-trial doses are weight-based (mg/kg). A flat-mg practice range is not established.

Safety

Serious warnings

  • FDA safety-risk page (content current as of 04/22/2026): 'Published case reports discuss serious adverse events including melanoma, posterior reversible encephalopathy syndrome, sympathomimetic toxidrome and priapism.' No label or boxed warning exists for this molecule.6
  • Review: 'Four case reports have described melanomas emerging from existing moles either during or shortly after the use of melanotan.' The same review states 'conclusive evidence linking these phenomena is lacking.'7
  • Case report: a 39-year-old man injected 6 mg of internet-purchased Melanotan II subcutaneously and developed systemic toxicity with sympathomimetic excess and rhabdomyolysis. Presenting creatinine was 2.25 mg/dL, and CPK rose from 1760 to 17773 IU/L. He was in the ICU for 3 days.8
  • Case report: acute low-flow priapism after abdominal subcutaneous injection of melanotan. The patient 'had not yet recovered erectile function at 4-week follow-up'.9
  • Posterior reversible encephalopathy syndrome after subcutaneous melanotan (case report in a letter). This is the primary report behind the PRES warning on the FDA page.10
  • Renal infarction most likely attributed to Melanotan II (case report and review). The authors raise a possible thrombotic or direct renal toxic mechanism. Rhabdomyolysis and renal failure with Melanotan II have also been described.11
  • Acute ischemic priapism after subcutaneous melanotan II that failed cavernosal aspiration/irrigation and intracavernous phenylephrine and required operative penoscrotal decompression. Priapism with MT-II overdose is reported separately (letter).12
  • Melanoma in a 20-year-old woman (Fitzpatrick II) three months after a 3-4 week MT-II self-injection course combined with sunbed use. Mucosal (oral) malignant melanoma in a 22-year-old woman after MT-II nasal spray. These are case reports, and causality is not established.13
  • Mucosal malignant melanoma of the anterior maxilla after MT-II nasal spray used for tanning (case report).14

Contraindications

  • Pregnancy and breastfeeding. The DermNet NZ patient-education page (not label text) states that no evidence exists for use of melanotan II in pregnancy or breast feeding, and 'it is recommended that it should be avoided'.5
  • Analog-derived (bremelanotide FDA label; no MT-II label exists): contraindicated in uncontrolled hypertension or known cardiovascular disease. Apply as a cautious exclusion for MT-II.15
  • Melanoma history, dysplastic or atypical nevi, or familial atypical mole and melanoma (FAMMM) syndrome. A 16-year-old with FAMMM developed darkened nevi and an enlarging nevus after MT-II plus UV tanning (case report). This supports excluding these patients.16

Adverse effects

  • Phase I: mild nausea at most dose levels, a stretching and yawning complex, spontaneous penile erections lasting 1-5 hours, increased pigmentation in 2 subjects, and Grade II somnolence and fatigue in 1 of 2 subjects at 0.03 mg/kg.1
  • ED crossover study (n=10 organic ED, 0.025 mg/kg): nausea and stretching/yawning were more frequent with MT-II. Severe nausea followed 4 of 19 injections (about 21% per injection).2
  • Pooled review at 0.025 mg/kg: severe nausea in 12.9% of subjects. Increased sexual desire followed 13/19 (68%) MT-II doses vs 4/21 (19%) placebo doses.4
  • Case report: eruptive naevi and darkening of pre-existing naevi within 24 hours of a single injection of melanotan II.17
  • Analog-derived (bremelanotide label), not studied for MT-II: focal hyperpigmentation developed in 38% of patients after 8 daily doses and was more likely in patients with dark skin. MT-II tanning protocols use daily loading, so counsel patients about possible lasting focal hyperpigmentation.15

Monitoring

  • Baseline full-skin exam with nevus mapping or dermoscopy, and re-examination for new or darkening nevi. This follows reports of melanocytic change. The review does not prescribe a schedule.7
  • Analog-derived (bremelanotide label): consider cardiovascular risk and make sure blood pressure is controlled before starting and periodically. The analog transiently increases blood pressure and reduces heart rate after each dose.15
  • Check creatinine and CK if muscle pain, dark urine, flank pain, or sympathomimetic symptoms occur (case reports of rhabdomyolysis, renal dysfunction, and renal infarction).8
  • Counsel patients that a prolonged painful erection is an emergency. Ischemic priapism requiring surgical decompression has been reported.12

Interactions

  • Analog-derived (bremelanotide label), not studied for MT-II: may slow gastric emptying and affect absorption of oral drugs. It may significantly decrease exposure to oral naltrexone, so avoid use with oral naltrexone products for addiction.15

Evidence

Controlled human data come from about 23 unique men in University of Arizona studies from 1996 to 2000. These are a 3-man phase I tanning and tolerability pilot (Dorr 1996) and two small double-blind crossover erectile dysfunction studies (n=10 psychogenic, n=10 organic). A fourth paper (Wessells 2000, Int J Impot Res, n=20) reviews the group's own experience and appears to pool those two cohorts, so it is not an independent study. All human dosing data are from adult men. There are no dosing data in women and no long-term data. Do not apply the bremelanotide 1.75 mg dose to MT-II. Doses were weight-based single injections (0.01 to 0.03 mg/kg). The authors recommended 0.025 mg/kg as the highest dose, and 0.03 mg/kg caused Grade II somnolence/fatigue. No regulator-approved labeling exists. Later literature consists of case reports of serious harm: melanoma, nevus changes, priapism (including ischemic priapism that needed surgery), PRES, renal infarction, and sympathomimetic toxicity with rhabdomyolysis.

Mechanism

Melanotan II is a cyclic heptapeptide analog of alpha-melanocyte stimulating hormone with superpotent melanotropic activity in vitro. It is described as a non-selective melanocortin receptor agonist. In the cited human trials it produced skin pigmentation, spontaneous penile erections, and increased sexual desire.14

Availability

Amounts offered

  • 10 mg

Custom strengths on request.

References

According to PubMed

  1. 1Evaluation of melanotan-II, a superpotent cyclic melanotropic peptide in a pilot phase-I clinical study.Life Sci 58(20):1777-84, 1996
  2. 2Effect of an alpha-melanocyte stimulating hormone analog on penile erection and sexual desire in men with organic erectile dysfunction.Urology 56(4):641-6, 2000
  3. 3Synthetic melanotropic peptide initiates erections in men with psychogenic erectile dysfunction: double-blind, placebo controlled crossover study.J Urol 160(2):389-93 (PII S0022-5347(01)62903-3; no DOI returned by PubMed), 1998
  4. 4Melanocortin receptor agonists, penile erection, and sexual motivation: human studies with Melanotan II.Int J Impot Res 12 Suppl 4:S74-9, 2000
  5. 5Melanotan IIDermNet NZ (patient-education site; author G. Shand, chief editor Dr A. Oakley, dermatologist); published August 2015, 2015
  6. 6Certain Bulk Drug Substances for Use in Compounding that May Present Significant Safety Risks (includes 'nominated but withdrawn' table)FDA, content current as of 04/22/2026, 2026
  7. 7Risks of unregulated use of alpha-melanocyte-stimulating hormone analogues: a review.Int J Dermatol 56(10):975-980, 2017
  8. 8Melanotan II injection resulting in systemic toxicity and rhabdomyolysis.Clin Toxicol (Phila) 50(10):1169-73, 2012
  9. 9Melanotan-induced priapism: a hard-earned tan.BMJ Case Rep 12(2):e227644, 2019
  10. 10Melanotan and the posterior reversible encephalopathy syndrome.Ann Intern Med 158(9):707-8 (letter), 2013
  11. 11Melanotan II: a possible cause of renal infarction: review of the literature and case report.CEN Case Rep 9(2):159-161, 2020
  12. 12Melanotan Tanning Injection: A Rare Cause of Priapism.Sex Med 9(1):100298, 2021
  13. 13Melanoma associated with the use of melanotan-II.Dermatology 228(1):34-6, 2013
  14. 14Melanotan II nasal spray: a possible risk factor for oral mucosal malignant melanoma?Int J Oral Maxillofac Surg 54(9):806-808, 2025
  15. 15VYLEESI (bremelanotide injection) Prescribing Information (analog label, used only as analog-derived evidence)FDA label, 2019, 2019
  16. 16Changes of melanocytic lesions induced by Melanotan injections and sun bed use in a teenage patient with FAMMM syndrome.Dermatol Pract Concept 2(3):203a10, 2012
  17. 17Eruptive naevi and darkening of pre-existing naevi 24 h after a single mono-dose injection of melanotan II.Eur J Dermatol 24(1):107-9, 2014
  18. 18Bulk Drug Substances Used in Compounding Under Section 503A of the FD&C Act (Categories 1-3)FDA, content current as of 05/14/2026, 2026

Last reviewed 2026-10-14. 39 figures checked against their sources. How this works