The melanocortin that does everything
A cyclic 7-residue melanocortin agonist that induces pigmentation and drives libido.
Educational content. This page describes Melanotan 2 for informational purposes only and is not medical advice, diagnosis, or treatment. Consult a licensed provider before starting, stopping, or modifying any therapy.
Melanotan 2 (MT-II) is a synthetic cyclic heptapeptide analog of alpha-melanocyte-stimulating hormone. It was designed in the late 1980s by Victor Hruby and Mac Hadley at the University of Arizona by truncating alpha-MSH to seven amino acids, substituting D-phenylalanine at position 7, and cyclizing the molecule through a lactam bridge between aspartate and lysine side chains. The resulting 23-membered ring structure has a molecular weight of 1,024 daltons.
Unlike the linear Melanotan 1 (afamelanotide, 13 amino acids), MT-II is a non-selective melanocortin receptor agonist that crosses the blood-brain barrier due to its compact cyclic structure. This gives it central nervous system effects that Melanotan 1 largely lacks. MT-II has never been approved by the FDA or any regulatory agency, and health authorities worldwide have issued warnings against its use. It served as the parent compound for bremelanotide (PT-141), which was developed specifically to isolate the sexual function effects.
MT-II activates G-protein-coupled melanocortin receptors by increasing intracellular cAMP and triggering protein kinase A dependent phosphorylation cascades. Its effects vary by receptor subtype and location in the body.
At MC1R on skin melanocytes, it drives phosphorylation of CREB, upregulation of microphthalmia-associated transcription factor (MITF), and increased expression of tyrosinase and related enzymes. This shifts melanin production toward photoprotective eumelanin. At MC4R in the hypothalamus and spinal cord, activation stimulates erectile signaling through nitric oxide-dependent pathways and suppresses appetite through satiety circuits. MC3R activation contributes to energy homeostasis and inflammatory modulation.
The non-selective nature of MT-II is both its pharmacological interest and its clinical limitation. Every injection activates all four receptor subtypes simultaneously, producing pigmentation, sexual arousal, appetite suppression, and nausea in varying degrees. This is why the derivative PT-141 was engineered for greater MC4R selectivity, and why Melanotan 1 was developed for MC1R-selective pigmentation.
The melanocortin that does everything
MT-II is a non-selective melanocortin receptor agonist that activates MC1R (driving eumelanin synthesis and skin darkening), MC4R (stimulating erectile function via central NO signaling and suppressing appetite), MC3R (modulating energy homeostasis), and MC5R (exocrine gland regulation). Its cyclic structure enables blood-brain barrier penetration for central effects.
Key studies supporting the therapeutic use of this peptide.
Subcutaneous doses from 0.01 to 0.03 mg/kg over two weeks increased skin pigmentation in 2 of 3 subjects. Spontaneous penile erections occurred 1 to 5 hours after injection. Side effects included mild nausea and fatigue at the highest dose.
Dorr RT, Lines R, Levine N, et al. — Life Sci, 58(20):1777-1784 (1996) · PubMed
8 of 10 men developed clinically apparent erections without sexual stimulation. Mean duration of tip rigidity above 80% was 38 minutes with MT-II versus 3 minutes with placebo (p = 0.0045).
Wessells H, Fuciarelli K, Hansen J, et al. — J Urol, 160(2):389-393 (1998) · PubMed
MT-II initiated erections in 12 of 19 injections versus 1 of 21 placebo doses. Mean tip rigidity above 80% lasted 45.3 minutes with MT-II versus 1.9 minutes for placebo (p = 0.047). Sexual desire increased significantly.
Wessells H, Gralnek D, Dorr R, et al. — Urology, 56(4):641-646 (2000) · PubMed
MT-II led to penile erection in 17 of 20 men. Increased sexual desire after 68% of MT-II doses versus 19% of placebo (p < 0.01). Nausea occurred in 41% and the stretching/yawning complex in 56% of subjects.
Wessells H, Levine N, Hadley ME, et al. — Int J Impot Res, 12(Suppl 4):S74-S79 (2000) · PubMed
Typical protocols used in clinical practice. Always consult a licensed provider for personalized dosing.
Subcutaneous Injection (Research)
Subcutaneous Injection (Research): Phase I recommended dose. Higher doses up to 0.157 mg/kg were tested but produced severe nausea.
No formal dose-finding Phase II or III trials were ever completed. All dosing data comes from limited Phase I studies with small sample sizes.
MT-II is not approved for any indication by any regulatory agency worldwide. The FDA, TGA (Australia), MHRA (UK), and HPRA (Ireland) have all issued public warnings against its use.
Products sold online are unregulated and carry risks of contamination, mislabeling, and incorrect concentrations. There is no quality assurance for any commercially available MT-II.
MT-II has a concerning safety profile that goes beyond typical peptide side effects. Multiple case reports document serious adverse events including rhabdomyolysis with renal dysfunction, ischemic priapism requiring surgery, and posterior reversible encephalopathy syndrome (PRES).
The relationship between MT-II and melanoma is unresolved. At least four case reports describe melanoma emerging during or shortly after MT-II use, though all cases had confounding factors such as fair skin, heavy UV exposure, and family history. MT-II stimulates melanocyte proliferation, and regulatory agencies consider this a legitimate safety concern.
All commercially available MT-II is unregulated. Analysis of products sold online has found contamination, incorrect peptide content, and mislabeling. Bloodborne virus transmission from shared injection equipment is an additional risk in unregulated use.
See how Melanotan 2 compares to peptides with overlapping benefits.
| Peptide | Primary Use | Administration | Cycle Length | Key Differentiator |
|---|---|---|---|---|
| Melanotan 2 | Pigmentation & Sexual Function | Injection | 2 weeks (clinical trial protocol) | Non-selective melanocortin agonist producing simultaneous tanning, sexual arousal, and appetite suppression, but with significant safety concerns that prevented regulatory approval |
| PT-141 (Bremelanotide) | Sexual Health | Injection (as-needed) | Ongoing as-needed | Only FDA-approved on-demand treatment working through CNS melanocortin/dopamine pathways rather than peripheral blood flow |
| Melanotan 1 (Afamelanotide) | Photoprotection & Pigmentation | Subcutaneous Implant | Every 60 days (ongoing) | The only FDA-approved melanocortin agonist, combining eumelanin induction with UV-independent DNA repair through a selective MC1R mechanism |
| AHK-Cu | Hair & Skin Regeneration | Topical | 8 to 12 weeks | Hair follicle-focused copper peptide with demonstrated dermal papilla cell protection and a biphasic dose response requiring precise formulation |
Current FDA classification and compounding eligibility.
The FDA placed this substance in Category 2 of the 503A bulk drug substances evaluation, flagging significant safety risks. 503A compounding carries FDA enforcement risk, so most pharmacies decline to prepare it and many physicians hesitate to prescribe it.
In April 2026, HHS Secretary Robert F. Kennedy Jr. announced that nominators withdrew 12 peptides from Category 2 of the FDA's 503A bulk drug substances evaluation, including this one. The FDA referred them to its Pharmacy Compounding Advisory Committee (PCAC) for re-evaluation at meetings beginning July 2026. If PCAC recommends Category 1 status and the FDA agrees, licensed 503A pharmacies could compound it under FDA enforcement discretion again. The outcome is not final.
Listed in Category 2. FDA and international regulatory agencies have flagged serious risks including potential melanoma induction, posterior reversible encephalopathy syndrome, and sympathomimetic toxidrome. Not approved for any indication and not eligible for compounding.
Listed as 'Melanotan II' in 503A Category 2
Last verified April 12, 2026. PepHookup tracks public FDA actions. This is not legal or medical advice.
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, 32(12):2555-2561 (1989)
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, 58(20):1777-1784 (1996)
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, 160(2):389-393 (1998)
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, 56(4):641-646 (2000)
Wessells H, Levine N, Hadley ME, et al. “Melanocortin receptor agonists, penile erection, and sexual motivation: human studies with Melanotan II.” Int J Impot Res, 12(Suppl 4):S74-S79 (2000)
Hadley ME, Dorr RT “Melanocortin peptide therapeutics: historical milestones, clinical studies and commercialization.” Peptides, 27(4):921-930 (2006)
Giuliano F, et al. “Melanocortin receptor agonists in the treatment of male and female sexual dysfunctions.” Expert Opin Investig Drugs, 23(11):1477-1483 (2014)
Nelson ME, et al. “Rhabdomyolysis and sympathomimetic toxicity from Melanotan II injection.” Clin Toxicol (Phila), 50(10):1053 (2012)
Habbema L, Halk AB, Neumann M, Bergman W “Risks of unregulated use of alpha-melanocyte-stimulating hormone analogues: a review.” Int J Dermatol, 56(10):975-980 (2017)
Looking into Melanotan 2? Find a provider who knows this peptide and can walk you through your options.
Find a ProviderA linear α-MSH analog that selectively activates MC1R to drive photoprotective pigmentation.
FDA-approved as Scenesse, a subcutaneous implant used in erythropoietic protoporphyria.
A copper-bound tripeptide that stimulates fibroblast proliferation and follicle signaling.
Used in cosmetic and hair-regeneration formulations; not on any FDA bulks list for compounding.