What is Melanotan II?
Melanotan II is a cyclic synthetic analogue of alpha-melanocyte-stimulating hormone (alpha-MSH) originally developed at the University of Arizona in the 1980s. Researchers sought a compound that could stimulate melanin production to provide natural photoprotection against UV radiation. Studies confirmed robust tanning effects but also revealed potent sexual side effects and appetite suppression — findings that led to the development of derivative compounds including PT-141 (bremelanotide) and the experimental obesity drug MTII. MT-II has never been approved by any regulatory agency.
Mechanism of action
Melanotan II acts as a non-selective agonist at melanocortin receptors MC1R, MC3R, MC4R, and MC5R. MC1R activation in melanocytes triggers eumelanin synthesis and UV-independent skin darkening. MC4R activation in the hypothalamus drives sexual arousal and appetite suppression. MC3R involvement contributes to energy homeostasis. Its cyclic structure confers greater metabolic stability than linear alpha-MSH.
Researched benefits
- UV-independent melanin synthesis and skin tanning in clinical research subjects
- Sexual arousal and spontaneous erection in male participants in early clinical studies
- Significant appetite suppression in rodent and human pilot studies via MC4R
- Potential photoprotective effects against UV-induced skin damage
- Research use as a pharmacological probe for melanocortin receptor biology
Researched dosage
Most research protocols use 250–1000 mcg administered 1× per day via subcutaneous injection. Research protocols typically use 250–1000 mcg subcutaneously. Most protocols start at 250 mcg to assess tolerance before escalating. MT-II is not used daily continuously; most research cycles are 4–6 weeks. Not for use without UV exposure for melanin production goals — some sun or UV exposure is required for melanin deposition.
A typical cycle runs 4 weeks on, then 4 weeks off before reassessment.
Use the calculator below to convert your target Melanotan II dose into exact insulin-syringe units.
Reconstitution & storage
A standard 10 mg vial reconstituted with 2 mL of bacteriostatic water yields 5000 mcg/mL. Lyophilized vials stable at 2–8°C. Reconstituted solution should be refrigerated and used within 30 days. Protect from light.
Side effects & considerations
- Nausea, especially at doses above 500 mcg (very common in early research)
- Facial flushing and warmth within minutes of injection
- Spontaneous erections in male research subjects (MC4R effect)
- Darkening of existing moles and nevi — dermatological monitoring recommended
- Fatigue and yawning reported acutely after administration
Melanotan II stacks
- Melanogenesis Research — paired with GHK-Cu. Combined skin pigmentation and collagen/repair signaling. Researchers studying skin biology have paired MT-II (melanogenesis) with GHK-Cu (collagen synthesis and gene modulation) to model comprehensive skin health endpoints.
Selected research
- Melanotan II, a melanotropin agonist, increases ejaculation latency — Pharmacology Biochemistry and Behavior, 1996
- Synthetic melanotropic peptides as potential drugs: a review — Expert Opinion on Investigational Drugs, 2001
- Alpha-MSH analogues: structure and activity relationships for melanocortin receptor subtype selectivity — Peptides, 2005