Melanotan II
| Category | Other Peptides |
| Goals | Sexual Health · Skin & Hair |
| Evidence level | Preclinical / Anecdotal (no approved human use; notable safety signals) |
| Legal status | Research-only — not approved; multiple regulators warn against it |
| FDA status | Not approved; flagged by FDA/MHRA/TGA as unsafe/unlicensed |
| Half-life | Not well established (engineered to outlast native α-MSH) |
| Routes | Subcutaneous (most common); intranasal reported |
| CAS / MW / Sequence | 121062-08-6 · 1024.2 g/mol · Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2 (cyclic heptapeptide) |
| Last reviewed | 2026-06-05 |
In one line
A synthetic, non-selective melanocortin receptor agonist used (research-only) to stimulate skin pigmentation/tanning and libido — with a notably troublesome side-effect profile and no regulatory approval anywhere.
Evidence at a glance
Melanotan II is not approved for human use in any jurisdiction, and the FDA, UK MHRA, and Australian TGA have issued safety warnings. Documented harms include nausea, blood-pressure changes, priapism, and darkening/new moles, and there are case reports of melanoma associated with use. Treat all human-use claims as unproven and risky. See Evidence Grading Explained and the Disclaimer.
Key Takeaways
- A cyclic heptapeptide analogue of α-MSH that activates melanocortin receptors non-selectively (MC1, MC3, MC4, MC5).
- MC1 activation drives tanning (melanogenesis); MC4 activation drives libido/erections — hence its dual reputation.
- No approval anywhere; sold purely as a research chemical/grey-market product.
- Well-documented side effects: nausea, facial flushing, spontaneous erections/priapism, and darkening of moles/freckles plus possible new nevi — with melanoma case reports.
- Its refined relative PT-141 (bremelanotide) became an FDA-approved libido drug; MT-II itself did not.
What Is It
Melanotan II (“MT-2”/“MT-II”) is a synthetic cyclic heptapeptide modeled on α-melanocyte-stimulating hormone (α-MSH). It was originally developed to induce skin tanning with less UV exposure by stimulating melanin production, and was observed to also produce sexual arousal/erections as a side effect — the observation that led to development of PT-141. It has never been approved as a medicine and is marketed informally as a “tanning peptide.”
Mechanism of Action
- Non-selective melanocortin agonism (established) — agonist at MC1, MC3, MC4, and MC5 receptors.
- MC1 → melanogenesis (established) — stimulating melanocytes to produce more eumelanin, darkening skin (the basis of “tanning” claims).
- MC4 → central sexual effects (established mechanism) — activation in the CNS produces arousal and erections, sometimes to the point of priapism.
- Appetite suppression (observed) — melanocortin signaling reduces appetite in some users.
Limitations
Because it is non-selective, MT-II hits multiple receptor systems at once, which is why benefits (tanning, libido) come bundled with broad side effects (nausea, flushing, pigment changes, cardiovascular effects).
Evidence by Outcome
| Outcome | Evidence | Notes |
|---|---|---|
| Skin tanning / increased melanin | Preclinical / Anecdotal | Mechanistically clear and widely reported; no approved human product |
| Libido / erectile effect | Anecdotal / Preclinical | Basis for spin-off to PT-141; not an approved use |
| Appetite suppression / weight | Preclinical | Seen with melanocortin agonism; not a validated use |
| Photoprotection / skin-cancer prevention | Not established | Tanning is not proven to reduce skin-cancer risk; melanoma case reports exist with MT-II |
Reported Dosing
Not medical advice
There is no approved or validated dose. Figures below are community-reported only and carry real documented risks. See Reconstitution & Dosing Math and Injection Technique.
| Phase | Dose (reported) | Frequency | Notes |
|---|---|---|---|
| ”Loading” | ~250–500 µg/day | Daily | Higher nausea; some titrate up slowly |
| ”Maintenance” | ~250–1000 µg | ~1–3×/week | After desired pigmentation reached |
Sun exposure
Tanning still requires UV, which carries its own skin-cancer risk; combining MT-II with UV does not make tanning safe.
Pharmacokinetics
Specific human half-life is not well established. MT-II was engineered to be more stable and longer-acting than native α-MSH, which has a half-life too short to be practical. Used subcutaneously. See Half-Life & Pharmacokinetics.
Side Effects & Risks
- Nausea and vomiting — very commonly reported, especially early.
- Facial flushing, yawning, stretching complex shortly after dosing.
- Spontaneous erections / priapism in males — a prolonged erection is a medical emergency and can cause permanent damage if untreated; documented in case reports.
- Pigment changes: darkening of existing moles/freckles, new moles (nevi), dark nail lines — and case reports of melanoma associated with use; any changing mole warrants dermatologic evaluation.
- Cardiovascular: blood-pressure changes have been reported.
- Appetite loss.
- Sourcing risk: unregulated product with unknown identity, purity, and contamination risk — see Sourcing and Red Flags & Scams.
- See Side Effects & Risk Management and Bloodwork & Monitoring.
Cycling
No evidence-based protocol exists. Community use typically front-loads to reach pigmentation, then tapers to intermittent “maintenance,” but this is not validated and does not mitigate the documented risks. See Cycling.
Stacks It Appears In
- Generally used alone for tanning/libido. Not a standard component of recovery or performance stacks.
Comparisons
- PT-141 — the refined, FDA-approved descendant focused on libido (premenopausal HSDD). MT-II is broader-acting, unapproved, and carries the tanning effect and a heavier side-effect load.
- Melanotan I (afamelanotide) is a related, more MC1-selective compound approved in some regions for a rare photosensitivity disorder — distinct from MT-II.
Sourcing & Quality
Sold exclusively as an unregulated “research chemical”; identity and purity are not guaranteed and the product is unapproved everywhere. Evaluate critically before trusting anything: How to Read a CoA, Red Flags & Scams, Sourcing. Reconstitution and storage: Reconstitution & Dosing Math, Storage & Handling. No vendors are endorsed here.
Legal & Regulatory Status
(As of 2026-06-05.) Melanotan II is not approved for human use in any jurisdiction. The U.S. FDA, UK MHRA, and Australian TGA have issued consumer warnings against it, and it is unlawful to sell for human consumption in many countries. See Regulatory & Legal Status.
FAQ
Is Melanotan II approved or safe? No. It is unapproved everywhere and multiple regulators warn against it. Documented harms include priapism and pigment changes, with melanoma case reports.
Does it actually tan you? It stimulates melanin via MC1 receptors and users do darken, but UV is still typically involved and the practice is not proven safe — it may mask or accelerate skin changes.
Is it the same as PT-141? No. PT-141 (bremelanotide) is a refined relative that became an approved libido drug; MT-II is the broader, unapproved parent compound.
Why the spontaneous erections? MC4-receptor activation in the CNS produces arousal/erections; prolonged erection (priapism) is a recognized risk and a medical emergency.
References
- Wessells H. et al. — early clinical studies of Melanotan II on erectile response (melanocortin agonism and sexual function).
- U.S. FDA / UK MHRA / Australian TGA — consumer safety warnings on unlicensed “Melanotan”/Melanotan II products.
- Case reports linking Melanotan II to priapism and to changing/melanoma-associated nevi (dermatology and sexual-medicine literature).
- Dorr R.T. et al. — pharmacology of Melanotan II and melanocortin receptor agonism.
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