Melanotan II

What it is

A cyclic heptapeptide and nonselective melanocortin receptor agonist originally developed at the University of Arizona in the 1990s. Melanotan II activates MC1R through MC5R simultaneously, producing skin tanning (MC1R), sexual arousal (MC4R), and appetite suppression (MC3R/MC4R). Clinical development was halted due to safety concerns, and the compound is not approved for human use in any jurisdiction. It is widely discussed in biohacking and bodybuilding communities for cosmetic tanning and libido effects. Regulatory agencies including the FDA, Health Canada, TGA, and EMA have issued explicit warnings against its use. PT-141 (bremelanotide), the FDA-approved HSDD drug, is a metabolite of Melanotan II.

Community-reported ranges

Dose ranges sourced from published phase I data (Dorr et al., 1996) and community forum discussions. Not dosing guidance. This compound is not approved for human use anywhere in the world.

Frequently discussed alongside

Based on community forum discussions. Not a recommendation to combine compounds.

Published research

A pilot phase I study (Dorr et al., 1996) evaluated subcutaneous doses of 0.01-0.03 mg/kg in healthy volunteers, demonstrating dose-dependent tanning and nausea. Wessells et al. (2000) documented penile erection effects in a small human study. Clinical development was discontinued due to the compound's nonselective receptor profile and associated safety signals. A 2021 qualitative study of online discussion forums (Evans-Brown et al.) documented widespread community use with self-reported side effects and harm-reduction practices. Case reports have documented serious adverse events including rhabdomyolysis with CPK levels exceeding 17,000 IU/L. No controlled efficacy trials have been completed for any indication. Community-reported dosing protocols are extrapolated from early phase I data and are not clinically validated.

Reported side effects

From community self-reports. Not from controlled studies.

Community users and early clinical studies have reported: nausea (dose-dependent, ~13% at clinical doses, higher at community doses), facial flushing, fatigue, somnolence, spontaneous erections lasting 1-5 hours, darkening of existing moles and appearance of new nevi, appetite suppression, yawning/stretching, and stomach cramps. Serious adverse events documented in case reports include rhabdomyolysis, renal dysfunction, sympathomimetic toxicity (tachycardia, hypertension), priapism, and posterior reversible encephalopathy syndrome (PRES). Product quality is a major concern — analytical studies have found 100+ unidentified ingredients in unregulated vials with actual peptide content significantly below labeled amounts. Long-term safety data does not exist.

Regulatory status