Melanotan II
MT-2 / MT-II
Melanotan II is a synthetic cyclic heptapeptide analog of alpha-melanocyte stimulating hormone (alpha-MSH) that acts as a non-selective agonist at melanocortin receptors MC1R through MC5R. Developed at the University of Arizona in the 1990s, it was originally investigated for sunless tanning (photoprotection) but its non-selective receptor profile produces multiple effects including skin darkening, sexual arousal, appetite suppression, and nausea. It remains one of the most widely used research peptides globally despite never receiving regulatory approval and carrying a significant side effect profile.
Mechanism of Action
Non-selective melanocortin receptor agonist. Activates MC1R (tanning), MC3R/MC4R (sexual arousal and appetite suppression), and MC5R (exocrine gland function). Produces tanning, increases sexual arousal, and suppresses appetite through simultaneous multi-receptor activation.
Research Protocols
For research purposes only. Not medical advice.
Research protocols use 0.25-0.5mg daily via subcutaneous injection as a loading phase for 7-14 days. Maintenance: 0.5mg 1-2 times weekly. Start with low doses (0.25mg) to assess nausea tolerance. Some UV exposure accelerates tanning.
Research Notes
Clinical Research Status
Melanotan II was investigated in early clinical trials at the University of Arizona for photoprotection and erectile dysfunction but was never advanced to Phase 3 or regulatory approval. Clinuvel Pharmaceuticals developed a related selective MC1R agonist (afamelanotide/Scenesse) that received FDA approval for erythropoietic protoporphyria. Melanotan II itself remains unregulated in most jurisdictions and is widely available through gray market suppliers.
Key Published Findings
Clinical studies confirmed dose-dependent melanogenesis (skin darkening) without UV exposure, though UV co-exposure significantly enhances and accelerates tanning response. Research documented spontaneous penile erections in male subjects during early dose-finding studies, leading to the development of PT-141. Studies show significant appetite suppression through MC4R activation, with measurable reductions in food intake at standard tanning doses.
Safety Profile
The non-selective melanocortin agonism produces a broad side effect profile including nausea (very common at initiation), facial flushing, fatigue, and involuntary stretching/yawning. Serious concerns include darkening of existing moles and nevi, which complicates dermatological skin cancer surveillance. Case reports document new nevus formation and changes in existing moles that required biopsy. The TGA (Australia) and FDA have issued warnings against its use due to safety concerns and lack of regulatory oversight.
Drug Interactions & Contraindications
Absolutely contraindicated in individuals with personal or family history of melanoma or dysplastic nevus syndrome due to potential promotion of melanocyte proliferation. Should not be used with other melanocortin agonists (PT-141, afamelanotide). Caution with antihypertensive medications due to potential for transient blood pressure changes. UV exposure combined with Melanotan II may increase melanoma risk compared to either alone.
Comparison to Related Compounds
PT-141 (bremelanotide) was derived from Melanotan II specifically to isolate the MC4R-mediated sexual function effects while minimizing MC1R tanning activity. Afamelanotide (Scenesse) is a linear alpha-MSH analog designed for selective MC1R activation for photoprotection without significant sexual or appetite effects. Melanotan I (afamelanotide) is selective for MC1R while Melanotan II activates all five melanocortin receptor subtypes.
Community Observations
Typically initiated with a loading protocol of 250-500mcg daily subcutaneously for 2-4 weeks, then maintained at 500mcg once or twice weekly with UV exposure. Nausea is nearly universal during the first 3-5 doses and commonly managed with antihistamines or by dosing before sleep. Users report significant skin darkening within 1-2 weeks and should be counseled about mandatory dermatological monitoring of moles and any new skin lesions.
Half-Life
~30-60 minutes
Reconstitution
Bacteriostatic water (BAC)
Storage
Lyophilized
Refrigerate 2-8C up to 24 months. Protect from light.
Reconstituted
Refrigerate 2-8C. Use within 30 days.
US Legal Status
Also Known As
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