Melanotan II

Typical use cases

Dosing guidelines

Titration

Community protocols commonly describe starting low (around 0.25 mg daily) and increasing gradually toward roughly 0.5-1 mg over 1-2 weeks to limit nausea, then dropping to intermittent maintenance once the desired pigmentation is reached. This is descriptive of reported community practice, not guidance.

Reconstitution

Lyophilized powder is reconstituted with bacteriostatic water; for example, a 10 mg vial with 2 mL yields 5 mg/mL. Diluent is typically added slowly down the vial wall and swirled gently rather than shaken.

Injection sites

Subcutaneous injection, typically into abdominal or other subcutaneous fat; subcutaneous is the most-studied route.

Storage & handling

Lyophilized powder is typically stored frozen at -20 C or below; after reconstitution, refrigerate at 2-8 C and use within roughly 1-2 weeks. Do not freeze the reconstituted solution.

Side effects

• Nausea Mild · Common
• Facial flushing Mild · Common
• Spontaneous penile erection / yawning-stretching complex Mild · Common
• Darkening, growth, or new appearance of moles and freckles (nevi) Moderate · Common
• Persistent or uneven hyperpigmentation Moderate · Uncommon
• Priapism (prolonged painful erection) Severe · Rare

Research summary

Melanotan II (MT-II) was developed at the University of Arizona in the late 1980s as a superpotent, metabolically stable cyclic analog of alpha-MSH intended to stimulate melanogenesis (skin pigmentation) without ultraviolet exposure, on the hypothesis that an induced tan might reduce skin-cancer risk. In a small 1996 pilot phase-I study (Dorr et al.), subcutaneous dosing produced measurable pigmentation in healthy volunteers after only a few low doses, while also commonly causing mild nausea, fatigue/somnolence, and an unexpected 'stretching and yawning' complex associated with spontaneous penile erection. These pro-sexual effects prompted separate human work: two small double-blind, placebo-controlled crossover studies (each roughly 10 men with psychogenic or organic erectile dysfunction) found that MT-II initiated erections far more often than placebo and increased self-reported sexual desire, with figures such as roughly 63% of drug injections versus about 5% of placebo injections in the organic-ED study. Mechanistically, MT-II is a non-selective agonist at melanocortin receptors MC1R (pigmentation), MC3R/MC4R (energy balance and central sexual and appetite effects), and MC5R, which is thought to explain its broad systemic profile. Despite these findings, MT-II was never approved for any indication; research instead pivoted to more selective successors, with afamelanotide (a related alpha-MSH analog, FDA-approved 2019 for erythropoietic protoporphyria) for pigmentation and bremelanotide (PT-141, an MC4R-focused analog approved 2019 for hypoactive sexual desire disorder in premenopausal women) for sexual function. The human evidence base for MT-II itself remains very limited (small samples, short duration), and the compound is widely sold as an unregulated, non-pharmaceutical 'research chemical' with no approved human use in any jurisdiction. Reported safety concerns include nausea, persistent or uneven hyperpigmentation, darkening and growth of moles/nevi, and case reports of priapism and melanoma; reviews note that evidence for direct melanoma causation is limited and confounded by concurrent UV exposure and by the unknown purity of illicitly sourced product.

Key references

• https://pubmed.ncbi.nlm.nih.gov/8637402/
• https://pubmed.ncbi.nlm.nih.gov/11018622/
• https://pmc.ncbi.nlm.nih.gov/articles/PMC2694735/
• https://pubmed.ncbi.nlm.nih.gov/16412534/
• https://pubmed.ncbi.nlm.nih.gov/15996790/

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