Melanotan II
Synthetic nonselective melanocortin receptor agonist developed in academic research.
Also known as: MT-II, MT2
Melanotan II is a synthetic peptide analog of alpha-melanocyte stimulating hormone. It was developed in academic research at the University of Arizona in the 1980s and has never been approved for human use. Multiple national regulators have issued warnings about unregulated products sold under its name.
Key facts
- Class
- Nonselective melanocortin receptor agonist
- Origin
- Academic research at the University of Arizona in the 1980s
- Regulatory status
- Not approved by the FDA, EMA, or any regulator
- Related approved drugs
- Afamelanotide (Scenesse) and bremelanotide (PT-141 / Vyleesi) are distinct molecules in the same family
- Known safety concerns
- Nausea, spontaneous erections, changes in pigmentation, atypical moles; poisoning cases reported with unregulated products
What is melanotan II?
Melanotan II is a synthetic peptide based on alpha-melanocyte stimulating hormone (alpha-MSH), the hormone that stimulates pigment-producing cells in the skin. It was developed as part of academic research on melanocortin receptors by researchers at the University of Arizona in the 1980s, with the original goal of identifying compounds that might protect against UV-induced skin damage.
The compound has never been approved for human use by any regulatory agency. Two related melanocortin agonists have been approved for specific narrow indications: afamelanotide (Scenesse), a subcutaneous implant for erythropoietic protoporphyria, and bremelanotide (Vyleesi), an injectable for hypoactive sexual desire disorder in premenopausal women. Melanotan II itself remains unapproved.
Mechanism of action
Melanotan II activates melanocortin receptors in a nonselective way, binding multiple receptor subtypes including MC1R, MC3R, MC4R, and MC5R. MC1R activation on melanocytes stimulates production of eumelanin, which can darken pigmentation. MC4R activation in the central nervous system influences appetite and sexual function, which explains the range of effects reported in preclinical and early clinical research.
- •MC1R activation stimulates melanin production in skin melanocytes
- •MC4R activation in the brain affects appetite and sexual arousal
- •MC3R and MC5R binding contributes additional peripheral effects
- •The nonselective nature of the binding underlies its broad side effect profile
Regulatory warnings and documented harms
Multiple regulators have issued public warnings about melanotan II products. The UK Medicines and Healthcare products Regulatory Agency (MHRA) has warned against its sale and use. The Australian Therapeutic Goods Administration (TGA) has also warned against it. The US Food and Drug Administration has issued warning letters to companies marketing it.
Documented adverse events associated with melanotan II use include nausea and vomiting, changes in moles and skin pigmentation, priapism, and in some reports, development of new atypical melanocytic lesions. Case reports describing serious adverse outcomes, including posterior reversible encephalopathy syndrome and rhabdomyolysis, have been published in medical journals.
Safety and regulatory context
Because melanotan II from unregulated sources has variable purity and identity, consumers and researchers cannot reliably know what is in any given vial. The FDA has not approved it, and multiple national regulators classify it as unauthorized.
Material sold as research melanotan II is intended strictly for laboratory use and is not cleared for human administration. The documented safety concerns and regulatory warnings are particularly relevant to this compound and are noted here for informational purposes.
Research sourcing
Melanotan II is listed by our research partner, GLP1 Research Lab, which supplies lyophilized peptides for laboratory use. Listings include product identifiers relevant to research documentation.
View Melanotan II listing at GLP1 Research LabAffiliate partnership. Metabolic Playbook may earn a commission on purchases made through this link at no additional cost to the researcher.