Melanotan II
Melanotan II is a synthetic, non-selective melanocortin receptor agonist that is not FDA-approved for any human use and is sold only as an unapproved research chemical, distinct from the FDA-approved, MC1R-selective compound afamelanotide (Melanotan I/Scenesse) and its FDA-approved MC4R-targeted derivative bremelanotide (Vyleesi).
This page is a research-orientation summary, not a dosing guide. For anything beyond general background, read the primary literature or talk to a qualified clinician — specifics like amount, frequency, or administration aren't something we publish here.
What it does & how it works
Melanotan II is a cyclic synthetic analog of alpha-MSH that acts as a non-selective agonist across multiple melanocortin receptors, including MC1R, MC3R, and MC4R. MC1R activation on melanocytes increases eumelanin synthesis and skin pigmentation, while its additional activity at central MC3R/MC4R circuits has been linked in early human studies to induction of penile erections and heightened sexual desire independent of genital stimulation, as well as appetite suppression. This broader, non-selective receptor activity is what distinguishes it pharmacologically from the more selective afamelanotide (MC1R) and bremelanotide (MC3R/MC4R).
Typical results seen in research
In small early-phase human studies, Melanotan II produced skin darkening as well as spontaneous, stimulation-independent penile erections and increased subjective sexual desire in men with erectile dysfunction, findings that helped drive later development of the more selective, FDA-approved derivative bremelanotide. Because it was never advanced through FDA-regulated clinical development for any indication, there is no standardized clinical safety or efficacy dataset, and case reports and regulatory warnings have described adverse effects including nausea, hyperpigmented lesions/moles, and rare cardiovascular events associated with unregulated use.
How it’s commonly used
Melanotan II is not available as an approved medical product; where it is used, it is typically self-injected subcutaneously as a compounded or unregulated 'research chemical' preparation, a use that falls entirely outside FDA oversight and drug-quality standards.
- Journal of Urology · 1998 Synthetic melanotropic peptide initiates erections in men with psychogenic erectile dysfunction: double-blind, placebo controlled crossover study
- International Journal of Impotence Research · 2000 Melanocortin receptor agonists, penile erection, and sexual motivation: human studies with Melanotan II
Curated from published literature for research orientation. Not an exhaustive review, and not a substitute for reading primary sources.