Melanotan II Research Overview (also known as MT-2)
A synthetic cyclic analog of alpha-MSH with broader melanocortin receptor activation than MT-1, producing strong tanning responses alongside significant libido-enhancing and appetite-suppressive effects. Studied for melanocortin receptor pharmacology, sexual function research, and metabolic effects.
What Is Melanotan II?
Melanotan II is a cyclic synthetic heptapeptide analog of α-MSH that differs from its linear cousin Melanotan I in both structure and receptor selectivity profile. Its cyclic structure confers greater metabolic stability, and its selectivity profile — spanning MC1R, MC3R, and MC4R — produces a broader range of biological effects including potent melanogenesis, appetite suppression, and pro-erectile/pro-libido effects that have driven its primary use in research.
Pro-Erectile and Libido Mechanisms
MC4R (melanocortin receptor 4) is expressed in hypothalamic and brainstem nuclei governing sexual arousal and erectile function. Melanotan II's MC4R activation initiates central pro-erectile pathways — increasing oxytocin release and downstream dopaminergic activation — that can produce spontaneous erections in male research subjects independent of tactile stimulation. This central mechanism distinguishes it from phosphodiesterase inhibitors (sildenafil, etc.) which work peripherally on penile vasodilation.
PT-141 Derivation and Side Effects
PT-141 (Bremelanotide) was derived directly from Melanotan II by identifying the active pharmacophore for sexual function while removing the melanogenic activity. Melanotan II's side effects include pronounced melanogenesis affecting nevi (moles) that should be monitored, nausea, facial flushing, and spontaneous erections — all dose-dependent and transient.
Quick Reference
| Literature-Reported Dose Range | 0.25-1mg |
| Literature-Reported Frequency | Daily initially, then 2-3x weekly for maintenance |
| Literature-Reported Cycle Length | 4-8 weeks on, 4 weeks off |
| Literature-Reported Washout | 4 weeks minimum to assess melanin fading |
| Storage | Refrigerate reconstituted peptide, protect from light |
| Sites Reported in Studies | Subcutaneous: abdomen (preferred), thigh, upper arm |
| Timing | Morning for tanning effects, evening for sexual effects (or 2-4 hours before) |
Research Indications
Skin Health
UV-Free Tanning
Stimulates natural melanin production for darker skin tone without sun damage
Photoprotection
Increased melanin provides natural SPF and reduces sunburn risk
Even Pigmentation
Promotes uniform tanning and may help with certain pigmentation disorders
Hormonal
Enhanced Libido
Increases sexual desire in both men and women through central effects
Erectile Function
Improves erectile quality and spontaneous erections in men
Female Arousal
Enhances genital arousal and sexual satisfaction in women
Metabolic
Appetite Suppression
Reduces food intake through MC4R activation in hypothalamus
Fat Loss Support
May enhance fat oxidation and metabolic rate
Glucose Metabolism
Emerging evidence for improved insulin sensitivity
Research Protocols
As reported in cited literature and research-community logs (see Research Citations below) — not a personal dosing recommendation.
| Research Application | Dose | Frequency | Route |
|---|
| Initial Loading | 0.25mg | Daily | SubQ |
| Tanning Maintenance | 0.5-1mg | 2-3x weekly | SubQ |
| Sexual Enhancement | 0.5-1mg | As needed | SubQ |
| Minimal Side Effects | 0.1-0.25mg | Every other day | SubQ |
| Photoprotection | 0.5mg | 2x weekly | SubQ |
Timing
Morning for tanning effects, evening for sexual effects (or 2-4 hours before). Typical onset: tanning: 7-10 days, Sexual: 2-4 hours, Appetite: immediate.
Peptide Interactions
Both act on melanocortin receptors - combining may cause excessive side effects including nausea and blood pressure changes
Redundant mechanism - both stimulate same melanocortin receptors, increasing risk of side effects without additional benefit
May enhance sexual effects - monitor for prolonged erections and cardiovascular effects, especially blood pressure
MT-II can affect blood pressure - monitor closely if combining with antihypertensives
No known interactions - different mechanisms of action and receptor targets
No documented interactions - work through different pathways (GHRH/ghrelin vs melanocortin)
MT-II has appetite suppressing effects - monitor for excessive appetite reduction when combining
No specific studies on interaction - consult healthcare provider as both can affect metabolism
Absolute contraindication. MT-2 potently activates MC1R on melanocytes, stimulating melanin production. In individuals with melanoma history or dysplastic nevus syndrome, this carries unacceptable risk of promoting existing atypical cells. Multiple health authorities (MHRA UK, TGA Australia) have issued formal warnings.
Both activate MC1R and MC4R. Combining creates excessive melanocortin receptor stimulation — compounded nausea, blood pressure changes, and skin pigmentation effects. Use one or the other, never both.
MT-2 can cause transient blood pressure changes. Combining with PDE5 inhibitors (often used for the same sexual function indication) risks additive hypotension. If combining, start at minimal doses of each and monitor blood pressure.
Reported Research Timeline
01Day 1–3 (reported in cited studies): possible nausea, flushing, and fatigue after injection
02Day 3–7 (reported in cited studies): increased spontaneous erections (men), enhanced arousal
03Week 1–2 (reported in cited studies): noticeable skin darkening, reduced appetite
04Week 2–4 (reported in cited studies): significant tanning, stabilized sexual effects
05Week 4+ (reported in cited studies): maintained tan with less frequent dosing
Safety Notes
Included for harm-reduction awareness only, in the event this compound is encountered outside its labeled research use. Inclusion here does not imply RUO Codes endorses, recommends, or instructs human use.
Start with very low dose (0.1-0.25mg) to assess tolerance
Nausea is common - can pre-treat with antiemetic if needed
Monitor moles and freckles for changes in size or color
Stay hydrated to minimize headaches and flushing
Avoid if history of melanoma or dysplastic nevi
Blood pressure may increase temporarily after injection
ABSOLUTE CONTRAINDICATION: Do not use if you have a personal or family history of melanoma or dysplastic nevus syndrome. MT-2 potently activates MC1R on melanocytes, stimulating melanin production — this mechanism is unsafe in individuals with atypical mole patterns or melanoma history. Multiple health authorities (MHRA UK, TGA Australia) have issued formal safety warnings.
Photograph and document all moles/nevi before starting. If any mole changes in size, shape, color, or texture during use — stop immediately and seek dermatological evaluation.
Nausea is nearly universal in the first 1–2 weeks at therapeutic doses, especially with higher starting doses. This does not mean to stop — reduce the dose and titrate up more slowly. Nausea typically resolves as the body acclimates.
Monitor blood pressure, particularly at doses above the established research range. Transient blood pressure changes have been documented — individuals with hypertension or cardiovascular disease should use caution and monitor.
Spontaneous erections are common in men, even in the absence of sexual stimulation, particularly in the first weeks of use at higher doses. If problematic, reduce dose.
Seek Medical Attention If:
Severe persistent nausea or vomiting
Chest pain or significant blood pressure elevation
Changes in mole appearance or new pigmented lesions
Prolonged painful erections (priapism)
Severe headaches or vision changes
Allergic reactions (rash, swelling, difficulty breathing)
Quality Indicators
Verified Marker
White to off-white lyophilized powder
Pure MT-II appears as white or slightly off-white powder before reconstitution
Verified Marker
Clear to pale yellow when reconstituted
Properly mixed solution should be transparent with at most a slight yellow tint
Acceptable Range
Protect from light exposure
MT-II is photosensitive - wrap vial in foil and minimize light exposure
Quality Concern
Brown or dark colored powder
Indicates oxidation or impurities - do not use
Quality Concern
Cloudy solution after mixing
Suggests degradation or contamination - discard immediately
Verified Marker
Vacuum sealed vial
Quality MT-II comes vacuum sealed - you should hear a "pop" when penetrating stopper
Research Citations
- Cardiovascular Effects Assessment (2018)
Human | Various doses | Acute monitoring | Mild BP elevation - Photoprotection in Fair-Skinned Individuals (2015)
Human (Fitzpatrick Type I-II) | 0.1mg/kg | 3 months | Reduced sunburn incidence - Female Sexual Arousal Disorder Trial (2004)
Human (Female) | 0.025mg/kg | Single dose | 73% reported arousal - Appetite and Food Intake Study (2001)
Human | 1mg daily | 6 weeks | 15% reduction in caloric intake - Phase II Trial of Melanotan II in Erectile Dysfunction (2000)
Human | 0.025mg/kg | 3 months | 80% response rate - Melanogenesis and UV Protection Study (1999)
Human | 0.16mg/kg daily | 10 days | Increased melanin density - 5-Hydroxypyrroloindoline Affords Tryptathionine and 2,2'-bis-Indole Peptide Staples: Application to Melanotan-II
Todorovic M, Blanc A, Wang Z, 2024, Chemistry - Evaluation of melanotan-II, a superpotent cyclic melanotropic peptide in a pilot phase-I clinical study
Dorr RT, Lines R, Levine N, 1996, Life Sci - CLIPSing Melanotan-II to Discover Multiple Functionally Selective hMCR Agonists
Tomassi S, Dimmito MP, Cai M, 2022, J Med Chem - Combining MALDI mass spectrometry imaging and droplet-base surface sampling analysis for tissue distribution, metabolite profiling, and relative quantification of cyclic peptide melanotan II
Chen B, Vavrek M, Gundersdorf R, 2020, Anal Chim Acta - A liquid chromatographic/tandem mass spectroscopic method for quantification of the cyclic peptide melanotan-II. Plasma and brain tissue concentrations following administration in mice
Hatziieremia S, Kostomitsopoulos N, Balafas V, 2007, Rapid Commun Mass Spectrom
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Research Focus
Sexual function, Tanning, Erectile dysfunction, Libido enhancement, Melanogenesis
Verified Vendors Carrying Melanotan II
Frequently Asked Questions
What should researchers watch for with Melanotan II?
Included for harm-reduction awareness only, in the event this compound is encountered outside its labeled research use. Inclusion here does not imply RUO Codes endorses, recommends, or instructs human use.
What should researchers expect over time with Melanotan II?
Day 1–3 (reported in cited studies): possible nausea, flushing, and fatigue after injection
How is Melanotan II typically administered in research?
As reported in cited literature and research-community logs (see Research Citations below) — not a personal dosing recommendation.
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