Melanotan II
Also known as: MT-II, MTII, Cyclo[Nle4,D-Phe7]-α-MSH
Melanotan II is a research compound not approved for human use. It is not approved by the FDA or EMA for any indication. Use is associated with serious side effects including changes to existing moles. For informational purposes only.
Overview
Melanotan II (MT-II) is a cyclic lactam analog of alpha-melanocyte stimulating hormone (α-MSH) that acts as a potent, non-selective melanocortin receptor agonist (MC1R, MC3R, MC4R, MC5R). Developed at the University of Arizona in the late 1980s, it produces eumelanin-driven skin darkening (tanning) via MC1R, sexual arousal and spontaneous erections via MC4R, and appetite suppression via MC3R/MC4R. Bremelanotide (PT-141) — now FDA-approved for female sexual dysfunction — was derived from Melanotan II.
Research Summary
Melanotan II's broad melanocortin receptor agonism produces a constellation of effects across multiple systems. MC1R activation in melanocytes upregulates tyrosinase, the rate-limiting enzyme in melanin synthesis, producing UV-independent skin darkening. MC4R activation in the CNS and spinal cord drives sexual arousal and erectogenic effects more potent than most PDE5 inhibitors, and also produces appetite suppression and reduced food intake (the same pathway exploited by weight-loss drugs targeting the melanocortin system). MC3R activation contributes to energy homeostasis effects.
Dosing Range
low
250mcg
moderate
500mcg
high
1000mcg
Units: mcg · Frequency: Daily during loading phase; 2–3x weekly for maintenance
Dosing ranges are aggregated from preclinical research and community protocols. Not medical dosing guidance.
Administration Routes
Reconstitution Notes
Reconstitute with bacteriostatic water to 1mg/mL. Store in amber vial — light-sensitive. Stable 28 days refrigerated. Begin with 250mcg to assess side effects (nausea is dose-dependent). Loading phase: daily injections until desired pigmentation level achieved (typically 2–4 weeks). Maintenance: 2–3x weekly.Step-by-step reconstitution guide →
Supplies you'll need
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Reported Side Effects
- Nausea (most common — especially first 30–60 minutes post-injection)
- Facial flushing
- Spontaneous erections (males — often unwanted at higher doses)
- Fatigue / yawning post-injection
- Darkening of existing moles and freckles
- Appetite suppression
- Possible melanoma risk with pre-existing atypical moles (MC1R activation drives melanocyte proliferation)
- Elevated blood pressure (uncommon)
Research Papers
3 peer-reviewed sourcesCommunity Experiences
Aggregated from public forums. Anecdotal — not clinical evidence.
Large body of community experience with MTII dosing, side effect management, nadir dosing to minimize nausea.
View original threadTanning community protocols for skin pigmentation — loading phases, maintenance doses, and UV exposure pairing.
View original threadOverview
Melanotan II was developed at the University of Arizona with the original goal of creating a sunless tanning agent that could reduce skin cancer risk by providing a melanin "sunscreen" without UV exposure. The research produced something far more pharmacologically complex — a non-selective melanocortin agonist with effects spanning pigmentation, sexual function, appetite, and energy balance.
The Melanocortin Receptor System
The 5 melanocortin receptors (MC1R–MC5R) are distributed across the body and brain:
| Receptor | Location | Function | |----------|----------|----------| | MC1R | Melanocytes, skin | Eumelanin production (tanning) | | MC3R | Brain, gut | Energy homeostasis, appetite | | MC4R | Brain, spinal cord | Sexual function, appetite, energy | | MC5R | Multiple tissues | Sebum secretion, diverse |
Melanotan II activates all of these — its "non-selective" profile is the source of both its utility and its side effect burden.
Tanning Effect (MC1R)
MC1R activation in melanocytes upregulates tyrosinase, driving conversion of tyrosine to melanin (specifically eumelanin — the dark brown/black form). The effect:
- Begins within 1–3 days of dosing
- Peaks at 2–4 weeks with consistent dosing
- UV exposure dramatically accelerates pigmentation (MT-II + sun exposure is far more effective than either alone)
- Maintained with lower dose 2–3x/week after desired shade achieved
Important: MT-II stimulates ALL melanocytes, including those in existing moles. Any atypical or dysplastic moles should be monitored by a dermatologist before using MT-II.
Sexual Effects (MC4R)
The MC4R in the spinal cord mediates penile erections via a NO-independent mechanism. At 500–1000mcg:
- Males: spontaneous erections (often within 1–4 hours)
- Both sexes: increased sexual arousal, fantasy, motivation
- Onset: faster than PDE5 inhibitors; independent of psychological state
This mechanism directly led to the development of Bremelanotide (PT-141) — a cyclic peptide derived from MT-II that retains MC4R selectivity with less MC1R activity.
vs PT-141
Melanotan II is the "full" agonist; PT-141 (Bremelanotide) is a more selective derivative:
- MT-II: Strong tanning + strong sexual effect
- PT-141: Primarily sexual effect with minimal tanning
- PT-141 is now FDA-approved (Vyleesi) for female hypoactive sexual desire disorder
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