Melanotan-2
Also known as: MT-2
The unregulated tanning peptide. Cheaper and more effective on libido than MT-1, but the side effect profile and mole-change risk make this the riskier of the two.
Overview
Melanotan-2 is a non-selective melanocortin agonist. It hits MC1R for pigmentation, MC4R for libido and appetite suppression, and MC3R for thermal regulation. That broader receptor profile is why MT-2 has a busier side-effect column than MT-1, and why it has the off-label reputation as a 'tan plus libido' peptide. It also produces the side effect MT-1 doesn't: spontaneous erections in men, and a real if uncommon priapism risk that has put people in the ER. The melanoma concern is the larger long-term issue. MT-2 is not approved anywhere; everything you read about it comes from European recreational use over the last twenty years and a small number of case reports, mostly about adverse events.
Evidence quality
No completed Phase 3 trials. Melanotan-2 was studied in the 1990s as an erectile dysfunction candidate before being abandoned in favour of bremelanotide (PT-141), which has cleaner pharmacology. All current use is grey-market and unregulated. Case reports in dermatology journals document melanoma in MT-2 users; the relationship is concerning but not formally proven.
Benefits & timeline
Benefits
- Reliable tanning, often faster onset than MT-1 because the dose schedule is more aggressive
- Libido increase in both sexes — a centrally mediated effect, similar mechanism to PT-141
- Appetite suppression — modest, but consistent
- Cheap and widely available on the grey market
Timeline
Week 1
Pigment darkening starts; libido increase often noticeable within the first few doses.
Week 2
Visible tan; nausea usually settles.
Week 4
Pigmentation plateau; loading dose ends.
Week 6+
Maintenance at lower frequency holds the colour.
After stopping
Pigment fades over 1–3 months; moles often remain darker.
Dosage protocols
Advanced
1 mg
every other day, then weekly maintenance
Beginner
250 mcg
daily for 7 days
Standard
500 mcg
daily for 10 days
Titration & adjustment
Loading: start at 250 mcg daily for the first week (lower than MT-1 because of the broader receptor profile). Escalate to 500 mcg daily for week 2 only if nausea is tolerable. Drop to maintenance of 500–1000 mcg twice weekly once your target tan is reached. Do NOT dose daily long-term — the spontaneous-erection side effect persists.
Injection timing
Same as MT-1 timing for tanning. For the libido side effect, dose 1–2 hours before desired activity. Avoid bedtime dosing — the spontaneous-erection side effect can disrupt sleep.
Side effects & contraindications
- moderateNausea, sometimes severe, especially in the first week. Worse than MT-1.
- moderateSpontaneous erections — uncomfortable, predictable, and at the higher end can become priapism (sustained erection over 4 hours), which is a urological emergency.
- moderateMole darkening and new naevi formation, with case reports of melanoma emerging in pre-existing moles during MT-2 use. Causation is debated; the temporal correlation is documented.
- mildAppetite suppression — usually welcome, occasionally to a worrying degree.
- moderateNo long-term human safety data; the grey-market track record is long but not systematically monitored.
Contraindications
- Any history of melanoma or many atypical naevi — the mole signal is too high a risk against a cosmetic benefit
- Sickle cell disease or other conditions predisposing to priapism
- Pregnancy or breastfeeding
- Concurrent use of erectogenic drugs (sildenafil, tadalafil) — additive priapism risk
- Children, adolescents, and anyone whose skin hasn't been surveyed by a dermatologist recently
Reconstitution & injection
A 10 mg vial reconstituted with 2 ml bacteriostatic water gives 5 mg/ml. A 500 mcg dose is 0.1 ml, which is 10 units on a U-100 insulin syringe. Subcutaneous in the abdomen. Start at 250 mcg to gauge nausea; 500 mcg is the standard loading dose only when the lower dose has been tolerated. Avoid bedtime dosing — the erection side effect can wake you up.
Open calculator pre-filledStorage after reconstitution
Refrigerate at 2–8 °C after reconstitution. Do not freeze. Light-protected. 30 days of stability at fridge temperature. Same photosensitivity caution as MT-1 — wrap the vial or store in an opaque bag. A vial left on a sunny windowsill for even one afternoon will degrade noticeably.
Common mistakes
Treating it as a 'better MT-1'.
Better approach: It isn't better; it's broader. The extra receptor activation buys you libido and appetite effects, but it also buys you the priapism, nausea, and mole-change risk. If pigment is your only goal, MT-1 is the cleaner pick.
Skipping the dermatology baseline.
Better approach: Get every mole photographed before you start. The peptide will darken them; you need a reference set so that when one changes shape or grows asymmetrically, the dermatologist has something to compare against.
Running it long-term as a chronic libido aid.
Better approach: The libido effect tolerates with chronic dosing and the priapism risk doesn't. PT-141 on demand is the cleaner tool for libido; MT-2 is for cosmetic tanning with libido as a side perk, not the other way around.
Doubling the dose to hit a darker tan faster.
Better approach: Pigmentation has a ceiling; nausea and side effects don't. Higher doses just produce more side effects without measurably more colour. Stay at 500 mcg per dose; if the tan isn't deep enough, extend the loading window, not the per-dose amount.
Real-world tips
- Inject in the morning, never close to bedtime. Erections at 2 AM are exactly as unpleasant as they sound, especially after the third one.
- Have a urology number on hand — priapism over 4 hours is an emergency, and treating it within the first 6 hours preserves erectile function long-term.
- Photographic mole tracking, monthly. Any mole that grows, changes border, changes colour, or itches gets reviewed by a dermatologist.
- Refrigerate the reconstituted vial. Stability beyond 4–6 weeks is dubious.
- Be honest with yourself about the cosmetic-versus-risk math. Self-tanner reaches the same end state visually with none of the systemic risk.
When something else is the better tool
Melanotan-1
Use instead when: Tanning alone is the goal and you want the cleaner side-effect profile. Same pigment effect, no libido side effects, no priapism risk.
PT-141
Use instead when: Libido is what you actually want and tanning is incidental. PT-141 is the more refined libido tool, with a real regulatory approval behind it.
DHA self-tanner
Use instead when: You're talking yourself into this peptide purely for the look. The cosmetic outcome is similar at a distance, with zero systemic exposure and no mole concern.
- Why does it cause erections?
- MT-2 activates MC4R in the central nervous system, which drives sexual desire and erection. It's the same mechanism PT-141 uses, but MT-2 isn't selective so you also get the MC1R (tanning) and MC3R effects in the same molecule.
- Is the melanoma risk real?
- There are case reports of melanoma developing in pre-existing moles during MT-2 use. The biological plausibility (melanocyte stimulation) exists. Formal causation hasn't been established because there are no large prospective trials, and there won't be. Treat it as a risk that the absence of proof doesn't disprove.
- Will the pigment last?
- Months, but fades. The melanin-laden cells turn over with normal skin renewal. Most people see noticeable fade by 8–12 weeks off.
- Can women use it?
- Yes. The libido effect is present in both sexes. The mole concern is the same. The pigment effect works identically.
- How is this different from PT-141?
- PT-141 is selective for the libido side of the melanocortin family and is approved for HSDD. MT-2 hits the same libido receptors plus the tanning receptors plus the appetite receptors, with a much broader side-effect signature.