Melanotan II
MT-II · MT2
Non-selective melanocortin agonist (tanning + libido); the precursor context for PT-141
Overview
Melanotan II is a synthetic cyclic analog of alpha-melanocyte-stimulating hormone (α-MSH) that acts as a non-selective agonist across the melanocortin receptor family, including MC1R (pigmentation), MC3R/MC4R (sexual arousal and appetite), and MC5R. It is the broader-acting parent context from which the more selective bremelanotide (PT-141) was developed, and it is the dual tanning-and-libido profile that drives community interest.
Its plasma half-life is roughly one to two hours, but downstream effects on pigmentation, appetite, and sexual signaling can persist for 24–48 hours or more because they depend on slower biological processes. Community protocols therefore use a daily 'loading' phase to build pigmentation followed by less frequent maintenance dosing; all such schedules are community-derived rather than clinically validated.
Safety concerns are material and warrant emphasis. As a broad melanocortin agonist, Melanotan II is commonly associated with nausea and flushing (especially in the first one to two weeks), spontaneous erections, appetite suppression, yawning, and — most importantly for dermatological caution — darkening of existing moles and the appearance of new pigmented lesions, which makes baseline skin photography and monitoring advisable. Rare but serious events including priapism and, at extreme overdose, rhabdomyolysis have been reported. This entry summarizes community practice for reference only and does not endorse use.
Key parameters
- Dose range
- 100 mcg–1 mg (community loading→maintenance)
- Frequency
- Daily loading, then 1–2× weekly maintenance
- Half-life
- ~1–2 hours (plasma)
- Route
- Subcutaneous
- Vial sizes
- 10 mg
- Regulatory status
- Not approved by any regulator. Material is sold for research use only. Carries notable safety concerns as a broad melanocortin agonist; this reference does not endorse use.
Mechanism of action
MC1R agonism (melanogenesis)
Activates melanocortin-1 receptors on melanocytes, stimulating eumelanin production and skin darkening — the basis of its use as a 'tanning' peptide and of its mole-darkening risk.
MC4R / MC3R agonism (sexual arousal)
Activates central melanocortin-3 and -4 receptors implicated in sexual arousal, the same pathway later targeted more selectively by bremelanotide (PT-141).
MC4R-mediated appetite suppression
MC4R activation in hypothalamic feeding centers reduces appetite, which is why decreased food intake is a commonly reported effect.
Dosing protocol & phases
| Phase | Weeks | Dose | Notes |
|---|---|---|---|
| Loading (community) | Days 1–14 | 100–250 mcg daily, increasing to 250–500 mcg | Low introductory doses to gauge nausea/flushing before building up; community-derived, not clinically established. |
| Build (community) | Weeks 3–6 | 500–1000 mcg daily | Higher daily dosing to reach desired pigmentation; side effects are dose-related. |
| Maintenance (community) | Ongoing | 250–1000 mcg once or twice weekly | Reduced frequency once target pigmentation is reached; lower-end maintenance is 250–500 mcg weekly or less. |
Reconstitution guide
For educational and research reference only. Not intended for human consumption, not medical advice. Compounds discussed are sold and used for laboratory research purposes only.
10 mg vial + 2 mL bacteriostatic water
Concentration5,000 mcg/mL · 5 mg/mL
| Target dose | Draw volume | U-100 units |
|---|---|---|
| 250 mcg | 0.05 mL | 5 |
| 500 mcg | 0.1 mL | 10 |
| 750 mcg | 0.15 mL | 15 |
| 1,000 mcg | 0.2 mL | 20 |
Standard community mix; small loading doses fall in the 5–10 unit range on a U-100 syringe.
10 mg vial + 1 mL bacteriostatic water
Concentration10,000 mcg/mL · 10 mg/mL
| Target dose | Draw volume | U-100 units |
|---|---|---|
| 100 mcg | 0.01 mL | 1 |
| 250 mcg | 0.025 mL | 2.5 |
| 500 mcg | 0.05 mL | 5 |
Higher-strength mix that halves draw volumes for the smallest introductory doses.
Reconstitution calculator
Pre-filled with Melanotan II's vial sizes. Adjust the water volume and target dose to see the exact draw, with warnings for doses that are hard to measure or won't fit a syringe.
At 5,000 micrograms per millilitre, a 250 microgram dose is 0.05 millilitres, or 5 units on a U-100 syringe, giving 40 doses per vial.
Supplies needed
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Recommended supply
Melanotan II — research vial
From our verified partner Dynotides, with a third-party certificate of analysis per batch.
Injection supplies
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Bacteriostatic water
Diluent for reconstituting lyophilized vials.
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Insulin syringes (U-100)
0.3–0.5 mL, 29–31 G for accurate small draws.
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Alcohol prep pads
Sterile swabs for the vial stopper and site.
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Sharps container
Safe disposal of used needles.
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Storage fridge
Keeps reconstituted vials at 2–8 °C.
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Insulated travel case
Cooled, TSA-friendly case for travel.
Missed-dose guidance
No approved-label guidance exists because Melanotan II is not an approved drug. During a community loading phase, a missed dose is generally taken when remembered the same day or otherwise skipped — doubling up increases the risk of nausea, flushing, and blood-pressure effects. Maintenance dosing is infrequent enough that a missed dose can simply be resumed on the next scheduled day.
Side effects & safety
| Category | Effect | Trial incidence |
|---|---|---|
| Gastrointestinal | NauseaAmong the most common effects, especially in the first 1–2 weeks of dosing. | — |
| Dermatologic | Flushing | — |
| Dermatologic | Darkening of moles / new pigmented lesionsA specific dermatological safety concern; baseline skin photography and monitoring are commonly advised. | — |
| General | Appetite suppression, yawning, fatigue | — |
| Urogenital | Spontaneous erections / priapismPriapism is a rare but medical-emergency-grade event. | — |
| Cardiovascular | Blood-pressure changes | — |
Clinical trials & evidence
Early melanocortin-agonist research
Phase 1/2 (research)Varies · Adults in mechanistic studies of pigmentation and sexual function
Early studies demonstrated tanning and erectogenic effects via melanocortin agonism, but Melanotan II itself was never developed through to regulatory approval; the program instead led to the selective agonist bremelanotide (PT-141).
Trial identifier needs verification
Storage & handling
- Lyophilized
- Store lyophilized powder frozen at −20 °C for long-term stability (years); refrigerated at 2–8 °C it is stable for several months. Protect from light.
- Reconstituted
- Refrigerate at 2–8 °C and use within ~2–4 weeks; aliquots can be frozen for a few months. Avoid repeated freeze-thaw cycles.
Comparisons
| Vs. | Target | Half-life | Dosing | Efficacy | Status |
|---|---|---|---|---|---|
| PT-141 (Bremelanotide) | Non-selective melanocortin vs MC4R-focused | ~1–2 h vs ~2.7 h | Community-dependent vs 1.75 mg per dose | Not established vs approved for HSDD | Not approved vs FDA-approved |
Sources & references
Frequently asked questions
How does Melanotan II relate to PT-141?
PT-141 (bremelanotide) is a more selective melanocortin agonist that emerged from Melanotan II research. Melanotan II is broader-acting — it hits MC1R for pigmentation as well as MC4R for sexual arousal — and, unlike PT-141, it is not an approved drug.
Why is mole monitoring recommended with Melanotan II?
Because it activates MC1R on melanocytes, Melanotan II can darken existing moles and is associated with new pigmented lesions. Dermatologists advise baseline skin photography and periodic checks; any changing lesion warrants evaluation.
Is Melanotan II safe?
It is not approved by any regulator and carries real safety concerns, including nausea, blood-pressure changes, priapism, and pigmentary changes to moles. This reference describes community practice for educational purposes only and does not endorse use.
Related protocols
PT-141 (Bremelanotide)
Bremelanotide
FDA-approved (2019) for premenopausal hypoactive sexual desire disorder
Kisspeptin
Kisspeptin-10
+56% penile rigidity vs placebo in men with HSDD (Comninos/Dhillo, 2023)
Looking to match this protocol to a verified research vial? Our partner supplier publishes a certificate of analysis per batch.
For educational and research reference only. Not intended for human consumption, not medical advice. Compounds discussed are sold and used for laboratory research purposes only.