Health & Research Goals
Melanotan II (MT-2)
Melanotan
Melanotan II is a synthetic cyclic heptapeptide analogue of alpha-melanocyte-stimulating hormone (alpha-MSH) originally developed …
Primary Description
Melanotan II is a synthetic cyclic heptapeptide analogue of alpha-melanocyte-stimulating hormone (alpha-MSH) originally developed at the University of Arizona as a potential sunless tanning agent and skin cancer chemoprevention tool. It is a non-selective melanocortin receptor agonist that activates MC1R (melanogenesis/tanning), MC3R and MC4R (sexual arousal, appetite suppression), and MC5R. Community use focuses on three primary applications: UV-accelerated skin tanning, libido enhancement, and appetite suppression. IMPORTANT: The combination of MT-2-induced increased melanogenesis with active UV exposure creates a complex skin cancer risk profile that every user must understand.
Key Benefits
- Tanning
- Libido enhancement
- Appetite suppression
Lyophilized powder: stable at room temperature for up to 3 weeks; long-term storage at -20C. Reconstituted: refrigerate at 2-8C, use within 30 days. Protect from light. Half-life approximately 33 hours allowing flexible dosing schedules.
Demonstrated Effects
- Accelerated and intensified UV-induced skin tanning via MC1R-mediated melanin synthesis
- Enhanced libido and sexual arousal in men and women via hypothalamic MC4R activation
- Improved erectile function in men (spontaneous erections reported in early trials)
- Appetite suppression (can be significant — up to 50% reduction reported by community)
- Even skin pigmentation and mole/freckle darkening
- Potential anti-inflammatory effects via melanocortin signaling (preclinical)
- Female sexual arousal enhancement (MC4R-mediated central pathway)
Proposed Mechanisms of Action
1. MC1R Agonism — Melanogenesis
Activation of melanocortin-1 receptor on melanocytes stimulates the cAMP signaling cascade, increasing tyrosinase activity and shifting melanin production toward darker eumelanin rather than lighter phaeomelanin. This amplifies the tanning response to UV radiation.
Primary driver of tanning effect; also responsible for new mole formation, mole darkening, and freckle enhancement.
2. MC4R Agonism — Sexual Arousal and Appetite
Hypothalamic MC4R activation modulates pro-sexual neurological pathways and satiety signaling. In men this manifests as increased libido and spontaneous erections; in women as enhanced sexual desire and arousal. MC4R activation also contributes to appetite suppression.
Drives the libido enhancement and appetite-suppressing effects. Also the mechanism underlying CNS side effects (flushing, yawning, stretching complex).
3. MC3R / MC5R Agonism — Secondary Effects
Non-selective activation of MC3R contributes to additional metabolic and anti-inflammatory effects. MC5R activation modulates sebaceous gland and exocrine function.
Contributes to the broader side effect profile including fatigue and systemic effects at higher doses.
Research Evidence & Clinical Data
Investigated Applications
Skin Tanning / Melanogenesis
Anecdotal: HighPrimary community use case. MT-2 dramatically amplifies the response to UV exposure. Even minimal sun or tanning bed exposure triggers substantial melanin production in the presence of MT-2. Results in darker, more even pigmentation. Some community members report visible tanning changes within 5-7 doses.
Preclinical basis: MC1R agonism drives eumelanin synthesis in melanocytes. Phase I clinical studies (University of Arizona, Dorr et al. 1996) confirmed tanning effect in all participants with minimal UV exposure.
Libido and Sexual Function
Anecdotal: HighWell-documented secondary use. Community reports enhancement of sexual desire in both men and women, improved erectile quality, and enhanced sensitivity. Effects begin within days of loading. Unlike PDE5 inhibitors, the effect is centrally mediated — it produces genuine increase in desire and arousal, not just mechanical vascular response.
Preclinical basis: Pilot Phase I study (Wessells et al. 1998, NEJM) — first clinical demonstration of MT-2 inducing erections in men with psychogenic ED via central MC4R activation. PT-141 (bremelanotide) was subsequently developed from MT-2 as a more selective sexual function compound.
Appetite Suppression / Weight Management
Anecdotal: ModerateMC4R activation in the hypothalamus contributes to satiety signaling. Community members report this as a notable but secondary effect. Appetite reduction can be significant enough to impact body composition when combined with caloric restriction.
Preclinical basis: Melanocortin MC4R signaling is a well-established mediator of energy homeostasis. Central MC4R deficiency causes hyperphagia and obesity in mice and humans.
Scientific References
- 1.Dorr et al. (1996). Evaluation of melanotan-II, a superpotent cyclic melanotropic peptide in a pilot phase-I clinical studyLife Sciences1996
First Phase I study demonstrating MT-2 produces tanning in all participants with minimal UV exposure. Also first documentation of spontaneous erections as a side effect.
- 2.
Safety Profile
Common Side Effects
- Nausea (most common, affects majority of users, especially at higher doses and during loading; peaks 2-4 hours post-injection)
- Facial flushing (30-60 min post-injection, lasts 1-2 hours)
- Spontaneous erections (men) — can be uncomfortable or problematic at high doses
- Yawning and stretching complex (CNS correlate of onset)
- Appetite suppression (can be significant)
- Darkening of existing moles and freckles
- New mole formation
- Fatigue
- Headache
- Elevated blood pressure (transient)
- Hyperpigmentation at injection sites
- Priapism (prolonged erection) — rare but serious at overdose levels
- Rhabdomyolysis and systemic toxicity reported with severe overdose (6 mg case report)
- Nausea
- Flushing
- Mole darkening
Contraindications
- Personal or family history of melanoma or dysplastic nevus syndrome — ABSOLUTE contraindication
- Active skin cancer or history of skin cancer
- Multiple atypical moles (dysplastic nevi) — high caution
- Very fair skin (Fitzpatrick type I) with heavy UV exposure habits — extreme caution
- Pregnancy and breastfeeding
- History of priapism or severe erectile dysfunction complications
- Cardiovascular disease — MT-2 can cause transient blood pressure changes
- Uncontrolled hypertension
- Melanoma history
- Skin cancer risk
Pre-Use Screening Checklist
Full skin check by dermatologist strongly recommended before starting MT-2. Photograph all moles. Any atypical, asymmetric, or rapidly changing moles = contraindication. MT-2 can cause existing moles to darken and new ones to appear.
Case reports of melanoma during MT-2 use, all involving UV exposure. Risk is poorly quantified but the combination of enhanced melanogenesis + UV DNA damage is mechanistically concerning.
Transient blood pressure elevation and vasodilation reported. Contraindicated in uncontrolled hypertension.
Concurrent PDE5 inhibitor use increases cardiovascular risk and priapism risk. Antihypertensives may have additive hypotensive effect with MT-2 flush response.
Legal & Regulatory Status
Not approved for any indication. Not a licensed drug. Sold as research peptide only. FDA has issued warnings against use.
Not explicitly listed on WADA Prohibited List, but melanocortin agonists and their effects on muscle and performance metabolism are under monitoring.
Not approved by COFEPRIS. Unregulated research peptide. Warnings exist in many jurisdictions against supply without prescription.
Not authorized by EMA. Illegal to supply as tanning agent in UK, EU member states issue warnings against use.
TGA has specifically warned against Melanotan II use. Illegal to supply without prescription. Multiple public health advisories issued.
Research Protocols
Dosing Protocols
Tanning — Loading Phase
Subcutaneous (abdomen or thigh preferred)Tanning — Maintenance Phase
SubcutaneousLibido Enhancement — On-Demand
SubcutaneousRoutes of Administration
Subcutaneous injection
Most commonStandard and only effective route. Injected into lower abdominal fat or thigh using insulin syringe (29-31 gauge, 0.5 inch). Oral administration is completely ineffective due to peptide degradation.
Use 1 mL insulin syringe. Inject at 45 degree angle. Massage site gently. Evening injection timing preferred to sleep through nausea peak.
Reconstitution Guide
Bacteriostatic water (0.9% benzyl alcohol) — standard. Sterile water acceptable but shorter stability.
1. Allow vial to reach room temperature. 2. Wipe septum with alcohol swab. 3. Inject bacteriostatic water slowly down the vial wall. 4. Gently swirl — do NOT shake. 5. Allow to dissolve fully (clear solution). 6. Label with date.
For 10 mg vial with 2 mL bacteriostatic water = 5 mg/mL. To dose 500 mcg: draw 0.1 mL on insulin syringe. To dose 250 mcg: draw 0.05 mL (5 units on U100 syringe).
Refrigerate at 2-8C, use within 30 days. Store upright, protect from light. Discard if discolored or cloudy.
Store at -20C for long-term. Stable at room temperature for up to 3 weeks. Desiccated, protect from moisture and light.
For tanning: inject any time of day, ideally evening to manage nausea. Combine with modest UV exposure — NOT aggressive tanning. For libido: inject 2-3 hours before sexual activity. Yawning/stretching complex often signals onset of effect.
Pharmacokinetics
| Half-Life | Approximately 33 hours, enabling every-other-day to twice-weekly maintenance dosing. Significantly longer than the endogenous alpha-MSH (minutes) due to cyclic peptide structure providing metabolic stability. |
| Absorption | Rapid subcutaneous absorption following injection. Peak plasma levels within 1-2 hours. |
| Distribution | Crosses the blood-brain barrier to activate central melanocortin receptors (MC4R in hypothalamus). Distributed to melanocytes in skin and hair follicles. |
| Metabolism | Metabolized via peptide bond hydrolysis. Cyclic structure resists rapid proteolytic degradation compared to linear alpha-MSH. |
| Molecular Structure | Cyclic heptapeptide with lactam bridge: Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-OH. MW 1024.18 Da. CAS 121062-08-6. |
Monitoring & Risk Management
Ongoing Monitoring Steps
- Skin and mole surveillanceAny new moles, rapid darkening of existing moles, irregular borders, color change, size increase. Use ABCDE criteria (Asymmetry, Border, Color, Diameter, Evolution). Photograph and compare.Check: Monthly during use, 3-monthly post-cycle
- Blood pressurePersistent hypertension beyond transient flush response. Baseline BP recommended before starting.Check: Weekly during loading phase
Critical Warning Signs
- Rapidly changing, darkening, or irregularly bordered moleDiscontinue MT-2 immediately. Dermatology consultation within days. Dermoscopy and possible biopsy required.Urgency: Within 24-48 hours
- Prolonged erection lasting 4+ hours (priapism)Emergency medical care required. Priapism lasting >4 hours can cause permanent erectile damage. Do NOT wait to see if it resolves.Urgency: IMMEDIATE
- Severe nausea, vomiting, extreme fatigue, muscle pain after injectionMay indicate overdose or contaminated product. Discontinue use. Seek medical evaluation if symptoms are severe or persist.Urgency: Within 24-48 hours
Featured in Stacking Protocols
Community-researched combinations involving this compound
PT-141 (Bremelanotide)
Melanocortin Libido StackCombining two melanocortin pathway activators for enhanced sexual function — MT-2 for baseline tanning + libido, PT-141 for on-demand sexual arousal
Both activate MC4R for sexual arousal. This combination is generally redundant and potentially risky — combined melanocortin stimulation increases CNS side effects (nausea, flushing, blood pressure changes). Community does NOT typically recommend concurrent use.
Not recommended to use concurrently. Choose one or the other for libido applications.
Sunscreen (SPF 30+)
Safe Tanning ProtocolHarm reduction — limiting UV-induced DNA damage during MT-2-enhanced melanogenesis
MT-2 increases melanin production; sunscreen reduces UV-induced DNA damage to the now-more-active melanocytes. Community consensus is that SPF protection during MT-2 use is non-negotiable harm reduction.
Apply broad-spectrum SPF 30+ before any UV exposure. Limit sun sessions to 15-20 minutes during loading. Avoid tanning beds entirely.