Overview
Melanotan II is a melanocortin peptide. Non-selective melanocortin receptor agonist (MC1R–MC5R).
With a half-life of ~1 hours, Melanotan II requires daily administration in most observed protocols. Administered via SubQ injection, it has a bioavailability of approximately 95% via its primary route.
Synthetic cyclic heptapeptide. Half-life approximately 1 hour. Subcutaneous administration. One-compartment model.
Mechanism of Action
Melanotan II's pharmacological activity involves the following key pathways:
Melanocortin Receptor Activation
Melanotan II binds to melanocortin receptors (particularly MC1R), stimulating melanogenesis — the production of melanin pigment in skin cells.
Melanin Synthesis
Activation of MC1R triggers a cascade that upregulates tyrosinase activity, the rate-limiting enzyme in melanin production.
Dosing Protocols
The following protocols represent commonly observed dosing patterns. These are observational summaries, not recommendations.
Dose
100 mcg/day
Route
Subcutaneous
Frequency
2-3 times daily
Duration
8-16 weeks
Dose
500 mcg/day
Route
Subcutaneous
Frequency
2-3 times daily
Duration
8-16 weeks
Reconstitution Steps
Melanotan II is supplied as a lyophilized (freeze-dried) powder and requires reconstitution before use. Common vial sizes: 5 mg, 10 mg.
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1
Allow Vial to Reach Room Temperature
Allow the lyophilized Melanotan II vial and bacteriostatic water to reach room temperature before handling.
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2
Draw Bacteriostatic Water
Using an insulin syringe, draw up 2.0 mL of bacteriostatic water. For a 10 mg vial this yields 5 mg/mL (5,000 mcg/mL).
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3
Add Water to Vial
Insert the needle through the rubber stopper and angle it so the water stream runs slowly down the inside wall of the vial — injecting directly onto the powder can degrade the peptide.
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4
Gently Swirl to Dissolve
Gently swirl (do not shake or vortex) the vial until the powder is completely dissolved into a clear solution.
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5
Draw Dose and Administer
Draw the required dose volume into a fresh insulin syringe and administer subcutaneously, typically into a pinched fold of abdominal skin. Evening administration is commonly observed to allow nausea to resolve during sleep.
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6
Label and Refrigerate
Label the vial with the reconstitution date and store refrigerated at 2–8°C, protected from light. Use within 2–4 weeks.
Quick Reconstitution Math
10 mg vial + 2.0 mL BAC water = 5 mg/mL (5,000 mcg/mL). A 0.5 mg (500 mcg) dose = 0.1 mL = 10 units on a U-100 syringe. A 0.25 mg (250 mcg) dose = 0.05 mL = 5 units. Use the Milligram reconstitution calculator for custom vial sizes.
Reconstituted Melanotan II should be stored refrigerated at 2–8°C and used within 2–4 weeks. Lyophilized powder should be frozen at −20°C prior to reconstitution. Avoid repeated freeze-thaw cycles. Discard if solution becomes cloudy or discoloured.
Frequently Asked Questions
What is Melanotan II and how does it work?
Melanotan II (MT-II) is a cyclic synthetic analogue of alpha-melanocyte stimulating hormone (α-MSH). It activates multiple melanocortin receptors including MC1R (pigmentation), MC3R, and MC4R (sexual arousal and appetite regulation). By binding to MC1R on skin melanocytes, it upregulates eumelanin production to accelerate tanning in response to UV exposure. Its additional activity at MC4R in the brain is responsible for the libido and appetite-suppressing effects that distinguish it from the more selective Melanotan I.
What is the half-life of Melanotan II and how should it be dosed?
Melanotan II has a plasma half-life of approximately 1 hour following subcutaneous injection, which is longer than Melanotan I. The broader receptor activity and longer half-life allow for once-daily dosing during loading phases. Libido effects are typically reported within 2–6 hours of injection and can persist for 24–48 hours in some users. Due to the short half-life, tanning effects are cumulative across the loading phase rather than dependent on maintained plasma levels.
How long does it take to see results with Melanotan II?
Visible skin darkening is commonly observed within the first 1–2 weeks of daily loading doses when paired with UV exposure. Initial signs include darkening of existing moles and freckles within days. A significant tan typically develops over 2–4 weeks of loading. Libido effects are often noted within the first few days of use. UV exposure accelerates visible pigmentation–without UV, melanin production increases but visible tanning is limited.
What are the most commonly reported side effects of Melanotan II?
Nausea is the most frequently reported side effect, often appearing within minutes of injection and lasting 1–2 hours–this is most pronounced in the early loading phase and commonly diminishes with continued use. Facial flushing, yawning, fatigue, and appetite suppression are also commonly observed. Spontaneous erections have been reported in male users due to MC4R activation. Darkening of moles and freckles is a direct pharmacological effect. Starting with a conservative dose of 100–250 mcg and gradually titrating is commonly observed to reduce initial nausea.
Does Melanotan II require UV exposure to produce a tan?
Yes. Like Melanotan I, MT-II increases melanin production capacity in the skin but visible tanning still requires UV exposure to oxidise the melanin. The compound amplifies tanning efficiency–users commonly report achieving a deeper tan with significantly less UV exposure than baseline. Short UV sessions of 5–15 minutes during the loading phase are typically incorporated into protocols to initiate visible pigmentation. Without any UV, skin darkening from MT-II alone is minimal.
How is Melanotan II different from PT-141?
PT-141 (bremelanotide) is a metabolite of Melanotan II. MT-II activates MC1R for tanning plus MC4R for libido enhancement, meaning one compound produces both effects simultaneously. PT-141 was developed specifically for sexual function and lacks significant MC1R activity, so it does not produce meaningful tanning. Users specifically seeking only libido effects without tanning often use PT-141, while those seeking both effects from a single compound use MT-II. PT-141 has received FDA approval for female sexual dysfunction (Vyleesi).