What Melanotan II Does
Melanotan II (MT-II) is a synthetic cyclic heptapeptide analog of alpha-melanocyte-stimulating hormone (alpha-MSH). It was originally developed at the University of Arizona in the 1990s by Dr. Victor Hruby and Dr. Mac Hadley as a sunless tanning agent to reduce skin cancer risk. The peptide activates melanocortin receptors throughout the body, producing three distinct pharmacological effects: skin darkening (MC1R), sexual arousal (MC3R/MC4R), and appetite suppression (MC4R).
The mechanisms that matter:
- MC1R activation on melanocytes — stimulates eumelanin synthesis (the brown-black pigment that provides UV protection), increasing melanin production independent of UV exposure. UV amplifies the effect by triggering melanin dispersal into keratinocytes
- MC3R/MC4R activation in the hypothalamus — produces sexual arousal and erectile function enhancement through the same central pathway as PT-141 (bremelanotide). This is a side benefit for many users and a primary benefit for others
- MC4R-mediated appetite suppression — engages the leptin-melanocortin pathway in the arcuate nucleus, reducing hunger signaling. The mechanism is pharmacologically validated by setmelanotide (Imcivree), an FDA-approved MC4R agonist for obesity
- Non-selective receptor profile — unlike PT-141 (which was engineered for MC3R/MC4R selectivity), Melanotan II hits all five melanocortin receptor subtypes. This produces broader effects but also broader side effects
- Loading/maintenance pharmacology — melanin production requires sustained melanocyte stimulation over days to weeks. Once melanocytes are “primed” and melanin stores are built, much less frequent dosing maintains pigmentation
Melanotan II vs Alternatives
| Feature | Melanotan II | Melanotan I (Afamelanotide) | PT-141 (Bremelanotide) |
|---|---|---|---|
| Primary use | Tanning + libido | Tanning only | Sexual function only |
| Receptor selectivity | Non-selective (MC1-5R) | Selective (MC1R) | Selective (MC3/4R) |
| Tanning effect | Strong | Strong (FDA-approved as Scenesse) | Minimal |
| Sexual arousal | Significant | None | Strong (FDA-approved as Vyleesi) |
| Appetite suppression | Moderate | Minimal | Mild |
| Nausea | Common | Less common | Common |
| Mole darkening risk | Yes | Yes (but better studied) | Minimal |
| Regulatory status | Not approved | FDA-approved for EPP | FDA-approved for HSDD |
| Half-life | ~1 hour | ~30 minutes | ~2.7 hours |
When to use Melanotan II: You want tanning as the primary goal and are comfortable with the secondary sexual arousal and appetite effects. You accept the mole monitoring requirements.
When to use Melanotan I: You want tanning with a cleaner side effect profile and are willing to source a less commonly available peptide. Afamelanotide (Scenesse) has been through clinical trials and is FDA-approved for erythropoietic protoporphyria (EPP).
When to use PT-141: Your primary goal is sexual function enhancement, not tanning. See the PT-141 Protocol.
Dosing Protocol
Standard Protocol
| Parameter | Detail |
|---|---|
| Loading dose | 250–500 mcg per day |
| Loading duration | 2–4 weeks (until desired tan achieved) |
| Maintenance dose | 500–1,000 mcg |
| Maintenance frequency | 1–2 times per week |
| Route | Subcutaneous injection (abdomen or thigh) |
| UV exposure | Recommended 4–6 hours post-injection |
Dose Tiers
| Phase | Dose | Purpose |
|---|---|---|
| Initial assessment | 250 mcg/day for 3 days | Assess nausea tolerance and sensitivity |
| Standard loading | 500 mcg/day for 2–3 weeks | Build melanin stores, develop base tan |
| Accelerated loading | 750–1,000 mcg/day for 1–2 weeks | Faster tanning (higher side effect burden) |
| Maintenance | 500–1,000 mcg, 1–2x per week | Sustain achieved pigmentation level |
Start at 250 mcg. Nausea is strongly dose-dependent, and the first injection tends to produce the worst nausea. After 3 days at 250 mcg, increase to 500 mcg if tolerated. Most users achieve satisfactory tanning at 500 mcg/day during loading.
Timing and UV Exposure
Melanotan II increases melanin synthesis, but UV exposure is what triggers melanin dispersal into the visible skin layers. The combination is synergistic:
- Inject in the evening — most users prefer bedtime injections to sleep through any nausea. The peptide stimulates melanin production overnight
- UV exposure the following day — 10–20 minutes of natural sunlight or 5–10 minutes in a low-pressure tanning bed, 4–6 hours after injection. This is enough to trigger melanin dispersal without excessive UV damage
- Do not overdo UV — Melanotan II dramatically increases tanning response. Users burn less easily but still accumulate UV damage. The goal is minimal UV for maximum tan, not extended sun exposure
- Fair-skinned users (Fitzpatrick I-II) should start with even shorter UV sessions (5–10 minutes sun, 3–5 minutes tanning bed) as response can be dramatic
Reconstitution
For a 10 mg vial — add 2 mL bacteriostatic water:
| Dose | Volume to Draw |
|---|---|
| 250 mcg | 5 units on insulin syringe |
| 500 mcg | 10 units |
| 750 mcg | 15 units |
| 1,000 mcg | 20 units |
Concentration: 5,000 mcg/mL. One 10 mg vial provides 20–40 doses during loading, significantly more during maintenance.
Storage: Refrigerate at 2–8°C after reconstitution. Use within 28 days. Protect from light. Unreconstituted vials can be frozen for long-term storage.
Cycling
- Loading phase: 2–4 weeks of daily injections. End when desired skin tone is reached
- Maintenance phase: 1–2 injections per week, indefinitely. Some users maintain with as little as one dose every 10–14 days, especially with continued sun exposure
- Seasonal use: Many users load in spring, maintain through summer, and discontinue in fall/winter. Pigmentation fades gradually over 1–2 months without maintenance
- No tolerance/desensitization concern: Unlike GH peptides, melanocortin receptor responsiveness does not diminish with long-term use for tanning purposes
What to Expect
Realistic Timeline
- Days 1–3: Nausea is at its worst. May notice mild facial flushing after injection. Some users experience spontaneous erections or increased libido within the first few doses. No visible tanning yet
- Days 4–7: Nausea typically diminishes. Existing moles and freckles may begin darkening — this is one of the earliest visible signs that melanocytes are responding. Slight overall skin darkening may be apparent, especially with UV exposure
- Weeks 1–2: Noticeable base tan developing, particularly in areas exposed to UV. Freckles and moles are visibly darker. Appetite suppression becomes apparent. Sexual arousal effects are consistent
- Weeks 2–4: Full loading effect. Skin tone is significantly darker than baseline. The tan appears natural and UV-assisted areas (face, arms, shoulders) are the deepest. This is the typical point to transition to maintenance dosing
- Maintenance phase: Achieved pigmentation is sustained with infrequent dosing. Without maintenance, tan fades over 4–8 weeks. With continued UV exposure, maintenance dosing can be very infrequent (weekly or less)
Who Sees the Best Results
- Fitzpatrick skin types II-III (light to medium skin that tans but also burns) — these users see the most dramatic transformation
- Fitzpatrick type I (very fair, always burns) — will tan, sometimes for the first time ever, but results take longer and require more cautious UV exposure
- Fitzpatrick types IV-V (olive to brown skin) — deepening of existing tone occurs but the change is less dramatic
What the Research Says
Melanotan II has been studied in clinical settings, though it has never completed FDA approval as a tanning agent:
University of Arizona development: Drs. Victor Hruby and Mac Hadley synthesized Melanotan II in the early 1990s as a more potent, longer-acting analog of alpha-MSH. Their research demonstrated that the cyclic structure conferred resistance to enzymatic degradation and enabled subcutaneous delivery. Initial human studies at the University of Arizona showed significant skin darkening in Caucasian subjects without UV exposure. Published in Life Sciences and the Annals of the New York Academy of Sciences.
Skin darkening trials: A controlled trial by Dorr et al. (1996) demonstrated that Melanotan II (0.010–0.025 mg/kg) produced statistically significant skin darkening measured by reflectance spectrophotometry. Subjects with fair skin (Fitzpatrick I-III) showed the most dramatic response. The tanning persisted for weeks after discontinuation. Published in Archives of Dermatology.
Sexual function research: During early tanning trials, researchers observed unexpected erectile responses in male subjects — this led to the spin-off development of PT-141. Subsequent studies confirmed MC3R/MC4R activation in the hypothalamus as the mechanism. A study by Diamond et al. (2004) demonstrated that Melanotan II improved erectile function in men with psychogenic ED. Published in International Journal of Impotence Research.
Appetite and body weight: Animal studies demonstrated that MC4R activation by Melanotan II reduces food intake through the same hypothalamic pathway later validated by setmelanotide (Imcivree). Human users consistently report reduced appetite during loading phases, though formal weight-loss trials were never conducted with Melanotan II specifically.
Melanoma risk data: There is no controlled clinical evidence that Melanotan II causes melanoma. However, there are published case reports of melanoma diagnosis in Melanotan II users, including a 2009 report in the British Journal of Dermatology. The concern is mechanistically plausible — melanocyte stimulation could theoretically accelerate the progression of pre-existing atypical nevi. The lack of long-term safety data is the primary risk factor. The Australian Therapeutic Goods Administration and European Medicines Agency have both issued warnings against Melanotan II use.
Derek (More Plates More Dates) has covered Melanotan II extensively, emphasizing the importance of low-dose loading to manage nausea, the necessity of mole monitoring, and the reality that most users prioritize tanning aesthetics over the libido and appetite effects. His protocols align with the 250–500 mcg loading dose range discussed above.
Safety
Common Side Effects
| Side Effect | Frequency | Notes |
|---|---|---|
| Nausea | ~60% (loading) | Dose-dependent, worst in first week, diminishes with continued use |
| Facial flushing | ~40% | Warmth and redness, resolves within 1–2 hours |
| Mole/freckle darkening | ~80% | Expected effect — melanocytes everywhere respond |
| Increased libido/erections | ~50% in males | MC3R/MC4R effect, may be unwanted. Can persist hours |
| Appetite suppression | ~40% | MC4R-mediated, usually moderate |
| Injection-site reaction | ~10% | Minor redness, itching |
| Fatigue/drowsiness | ~15% | Especially with evening dosing, often considered beneficial |
| Headache | ~10% | Usually mild, more common at higher doses |
Critical Warnings
Mole monitoring is mandatory. Melanotan II stimulates melanocytes — the cells that give rise to melanoma. Before starting Melanotan II:
- Photograph all moles (full body) as a baseline
- Learn the ABCDE criteria — Asymmetry, Border irregularity, Color variation, Diameter >6mm, Evolution (change)
- Self-check monthly during use — compare against baseline photos
- See a dermatologist if any mole changes. Do not delay
- Annual dermatology screening is strongly recommended for ongoing users
Skin cancer history is an absolute contraindication. If you or a first-degree family member have had melanoma, do not use Melanotan II.
Injection darkening patterns. Some users report localized hyperpigmentation around the injection site. This is not dangerous but can be cosmetically undesirable. Rotate injection sites.
Do not combine with PT-141. Both activate melanocortin receptors. Combining them amplifies nausea, blood pressure effects, and excessive melanocortin stimulation without added benefit.
Blood pressure. Melanotan II can cause a mild, transient increase in blood pressure. Users with uncontrolled hypertension should avoid use.
Do Not Use If
- Personal or family history of melanoma or atypical mole syndrome
- Large number of atypical nevi (dysplastic moles)
- Uncontrolled hypertension
- Active cardiovascular disease
- Pregnant or breastfeeding
- Under 18
- Concurrent use of PT-141 or other melanocortin agonists
- History of priapism (prolonged painful erections)
What Comes Next
- If your primary goal is sexual function — see the PT-141 Protocol for a more selective melanocortin agonist
- Explore other protocols matched to your goals in the Directory
- Learn proper injection technique — How to Inject Peptides
- Use the Reconstitution Calculator for exact unit counts
Frequently Asked Questions
What is the standard Melanotan II dosage? +
During the loading phase, 250–500 mcg per day via subcutaneous injection for 2–4 weeks until desired skin tone is achieved. Then transition to a maintenance dose of 500–1,000 mcg once or twice per week to sustain pigmentation. Start at 250 mcg to assess nausea tolerance before increasing.
How does Melanotan II differ from PT-141? +
Both are synthetic analogs of alpha-MSH and activate melanocortin receptors, but they were developed for different purposes. Melanotan II is a non-selective melanocortin agonist — it activates MC1R (tanning), MC3R and MC4R (sexual arousal), and MC5R (appetite). PT-141 (bremelanotide) was derived from Melanotan II but engineered for selectivity toward MC3R/MC4R — it enhances sexual function without significant tanning. If your primary goal is tanning, use Melanotan II. If your primary goal is sexual function, use PT-141.
How long does it take to see tanning results? +
Most users notice visible darkening within 7–14 days of daily loading at 500 mcg. The full effect develops over 3–4 weeks. UV exposure (sun or tanning bed) dramatically accelerates results — Melanotan II increases melanin production, but UV triggers melanin dispersal into the skin. Without any UV exposure, results are slower and less pronounced.
Does Melanotan II cause nausea? +
Yes, nausea is the most common side effect and is strongly dose-dependent. At 250 mcg, most users experience minimal nausea. At 500 mcg and above, moderate nausea lasting 30–60 minutes is common, especially in the first few days. Injecting before bed allows you to sleep through the nausea. Anti-nausea medication (ondansetron 4 mg) taken 30 minutes prior can also help.
Is Melanotan II safe for moles and skin? +
This is the most important safety consideration. Melanotan II stimulates melanocytes, which are the same cells involved in melanoma. It can darken existing moles and freckles, and there are case reports of new nevi (moles) appearing during use. Anyone with a personal or family history of melanoma should not use Melanotan II. All users should photograph their moles before starting and perform regular self-checks. See a dermatologist if any mole changes in size, shape, color, or border regularity.
Can I use Melanotan II without UV exposure? +
Technically yes — Melanotan II increases melanin synthesis regardless of UV. However, results without UV are significantly slower and less uniform. UV exposure triggers the release and dispersal of the newly produced melanin into the upper skin layers, producing a visible tan. Most protocols recommend 10–20 minutes of natural sunlight or 5–10 minutes in a low-pressure tanning bed 4–6 hours after injection to optimize results.
Does Melanotan II suppress appetite? +
Yes. Melanotan II activates MC4R receptors in the hypothalamus, which suppress appetite via the leptin-melanocortin signaling pathway. This is the same pathway targeted by setmelanotide (Imcivree), the FDA-approved MC4R agonist for genetic obesity. The appetite suppression is a secondary benefit for many users, though it can also be unwanted for those trying to gain weight.
How do I store Melanotan II? +
Unreconstituted lyophilized powder can be stored frozen (-20°C) for over a year or refrigerated (2–8°C) for several months. Once reconstituted with bacteriostatic water, store refrigerated and use within 28 days. Protect from light — melanocortin peptides can degrade with light exposure. Never freeze reconstituted solution.
Protocol Summary
| Research Dose | 250–1,000 mcg/day |
| Frequency | Once daily (loading), then 1–2x per week (maintenance) |
| Duration | Loading: 2–4 weeks, then maintenance indefinitely |
| Administration | Subcutaneous injection |