Melanotan II
Melanotan II (MT-II): synthetic α-MSH cyclic analog
Cyclic non-selective melanocortin receptor agonist developed at the University of Arizona (1980s) as a sunless tanning agent. No FDA approval. Sold illegally / as research chemical worldwide. Heavily warned against by regulators (FDA, MHRA, EU) due to documented serious adverse events including rhabdomyolysis, renal infarction, melanoma case reports, and priapism. Used by biohackers for tanning enhancement and secondary libido / appetite-suppression effects. Note: Afamelanotide (Melanotan I, Scenesse) IS FDA-approved for erythropoietic protoporphyria (a related but distinct compound).
At a glance
- Half-life
- ~33 min Approximate plasma t½ 30-60 min (community / vendor; no peer-reviewed human PK publication). Effects on appetite + sexual arousal persist hours longer than plasma residence; pigmentation persists weeks (melanin half-life).
- Routes
- SubQ
- Vial sizes
- 10 mg
- Evidence base
- 5 studies 4 human · 1 review
Mechanism
Non-selective agonist of all five melanocortin receptors (MC1R-MC5R). MC1R activation on melanocytes drives eumelanin synthesis (skin / hair / mole / freckle darkening). MC4R activation in hypothalamus → appetite suppression + sexual arousal + erection (men). MC3R contributes to sexual effects. MC5R → exocrine gland effects (sebum, sweat). More potent and less selective than PT-141: drives stronger MC1R pigmentation but at the cost of poorly controlled MC4R / cardiovascular / renal effects. Rapid progression of melanoma in a user; rhabdomyolysis documented at 6 mg dose; priapism requiring intervention at 10 mg; renal infarction reported. Comprehensive 2024 adverse-event review.
Dosing
Any amounts shown here are reported from published studies only. 4 of 5 catalogued studies involved human subjects. COMPOUND does not publish its own dosing guidance.
Where a study reports an amount, it appears in that study's entry below, attributed to the source.
Published evidence
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Human case report 2020
Melanotan II: a possible cause of renal infarction; review of the literature and case report
Middle-aged male right-sided renal infarction (CT-confirmed) attributed to MT-II. Proposed mechanisms: thrombotic pharmacological influence + direct renal toxicity.
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Human case report 2014
Melanoma associated with the use of melanotan-II
20-year-old woman developed gluteal melanoma after 3-4 weeks of MT-II + tanning bed use. Adds to literature linking MT-II + UV exposure to melanoma in young users.
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Human case report 2013
Melanotan II overdose associated with priapism
60M injected 10 mg MT-II SC → painful erection within 30 min. Documents priapism risk at supratherapeutic doses.
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Human case report 2012
Melanotan II injection resulting in systemic toxicity and rhabdomyolysis
39M overdose case (6 mg single dose). Sympathomimetic toxidrome: HTN, tachycardia, mydriasis, tremors. CPK 17,773 IU/L. Established MT-II overdose can cause life-threatening rhabdomyolysis.
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Review 2024
An overview of benefits and risks of chronic melanocortin-1 receptor activation
Comprehensive 2024 dermatology review. Documents at least 5 melanoma cases in MT-II users. Strong recommendation against unlicensed MT-II use.
Reported side effects
- Nausea
- Very common Moderate · Reported at nearly all dose levels. Peaks 30-90 min, resolves 2-4h. Worst during first 3-5 days of loading. Tolerance develops with continued use.
- Facial flushing
- Very common Mild · Within minutes of injection; transient.
- Spontaneous erections (men)
- Common Mild · MC4R-mediated. Reported by majority of male users at standard doses. Generally welcome but can occur unpredictably for hours post-dose.
- Darkening of moles, freckles, nail beds
- Very common Mild · Reversible darkening of pigmented lesions and nail matrix. Concerning for dermatologic monitoring; any dysplastic change or new lesion warrants biopsy. Multiple case reports of melanoma detection during/after use (PMID 24355990).
- Priapism (men)
- Rare Serious · Sustained painful erections >4h reported with overdose (e.g., 10 mg single dose → 8h erection). Surgical / pharmacologic emergency intervention may be required.
- Rhabdomyolysis
- Rare Serious · Case report: 39M injected 6 mg (6x recommended starting dose), CPK rose to 17,773 IU/L within 12h, ICU admission with IV fluids + sodium bicarb.
- Renal infarction
- Rare Serious · Case report: middle-aged male with right-sided renal infarction; thrombotic vs direct renal toxicity proposed.
- Melanoma (case reports)
- Rare Serious · Multiple case reports of melanoma diagnosed during or after MT-II use, all in users with additional risk factors (fair skin, family history, tanning bed use). Causal link not definitively established but biological mechanism is plausible (MC1R activation + UV synergy).
- Dose-dependent BP elevation
- Occasional Moderate · Sympathomimetic-like activation observed in overdose; moderate BP elevation at higher doses. Considered contraindicated in hypertension or cardiovascular disease.
Interactions
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PT-141 Redundant
Both are MCR agonists with overlapping pharmacology. Stacking is redundant and amplifies all MCR-mediated effects (pigmentation, BP, nausea).
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Stimulants Caution
MT-II overdose produces sympathomimetic toxidrome (HTN, tachycardia, tremors). Co-administration with stimulants creates additive sympathetic activation: severe BP spikes, arrhythmia risk.
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PDE5 inhibitors Caution
Both raise BP; both cause vasodilation. Co-use increases priapism risk (already documented for MT-II alone).
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UV exposure Caution
MT-II requires UV for full tanning effect, but multiple melanoma case reports involve MT-II + tanning bed use. Synergy of MC1R activation + UV DNA damage may increase melanoma risk.
Reconstitution and storage
10 mg vial + 2 mL BAC water = 5 mg/mL = 250 mcg per 0.05 mL (5 units on insulin syringe). 10 mg + 5 mL = 2 mg/mL = 250 mcg per 0.125 mL. Drip slowly down vial wall; do not shake.
Lyophilized: freezer (-20°C). Reconstituted: refrigerate 2-8°C, use within 28-30 days. Protect from light.