How does Melanotan II work?

It is a synthetic analog of alpha-MSH that activates melanocortin receptors non-selectively. Activating MC1R stimulates melanin production (skin tanning, often combined with UV exposure); activating MC4R drives sexual arousal and appetite suppression. So users report tanning plus increased libido and reduced appetite.

What are the main risks of Melanotan II?

Very common nausea (especially early doses), facial flushing, and spontaneous erections or priapism in men. The biggest dermatologic concern is darkening of existing moles and new moles or freckles, which can mask or complicate melanoma detection; melanoma, rhabdomyolysis, kidney injury and brain swelling (PRES) have been reported in users. Long-term safety data are limited and regulators warn against it.

How is Melanotan II different from PT-141 and afamelanotide?

Melanotan II is the unapproved, non-selective tanning peptide. PT-141 (bremelanotide) is its active metabolite, developed for sexual desire and FDA-approved in 2019 as Vyleesi. Afamelanotide, sometimes called Melanotan I, is a separate FDA-approved drug (Scenesse) for the rare condition erythropoietic protoporphyria. Only Melanotan II is unapproved.

Is Melanotan II banned in sport?

It is not confirmed to be explicitly named on the WADA Prohibited List. However, because it is not approved for human therapeutic use anywhere, WADA's S0 'non-approved substances' catch-all could apply. Athletes should check the current official WADA list and their anti-doping authority before any use; do not assume it is permitted.

Melanotan II: the tanning peptide, explained

Q: Is Melanotan II legal or approved?

No. Melanotan II is not approved as a medicine anywhere. The US FDA, UK MHRA, Australian TGA and Germany's BfArM have all warned specifically against it — it is sold unlicensed online with no guarantee of safety, purity or sterility, and selling it as a medicine is illegal in many countries.

Melanotan II is a synthetic melanocortin receptor agonist sold as an injectable "tanning peptide" — it darkens skin (and raises libido and suppresses appetite). It is unapproved everywhere, and unusually for this space, multiple national regulators have specifically warned against it. This page is the honest version, and the safety section is the point: how it works, the real risks (nausea, priapism, and the mole-darkening / melanoma-masking concern), how it differs from PT-141 and afamelanotide, the dosing math, and how to track it. It is not dosing or sourcing advice.

By OptiPin Editorial·Last verified June 2026

Status — as of June 2026

Unapproved. Regulators warn specifically against it. Melanotan II is not approved as a medicine in any country. The US FDA, UK MHRA, Australian TGA and Germany's BfArM have all issued warnings — it's sold unlicensed online with no guarantee of safety, purity or sterility, and selling it as a medicine is illegal in many places. There is a real dermatologic safety concern (mole changes / melanoma masking — see below). Nothing here is a recommendation to obtain or use it.

Class

Melanocortin agonist

Effects

Tanning · libido · appetite

Half-life

Limited data

Status

Unapproved · warned against

TL;DR

• Melanotan II is a non-selective melanocortin agonist (α-MSH analog) — MC1R drives tanning, MC4R drives libido + appetite suppression.
• Unapproved everywhere; FDA, MHRA, TGA and BfArM warn against it. Gray-market, unregulated purity.
• Real safety concerns: nausea, priapism, and darkening / new moles that can mask melanoma; rhabdo/PRES/renal case reports.
• Not the same as PT-141 (its approved metabolite, Vyleesi) or afamelanotide (Scenesse). This page is honest facts + tracking.

What it is

Melanotan II (MT-II, "Melanotan 2") is a synthetic cyclic heptapeptide analog of α-melanocyte-stimulating hormone (α-MSH) — a non-selective melanocortin receptor agonist. It activates several melanocortin receptors: MC1R (drives melanin production / skin tanning), MC4R (sexual arousal and appetite suppression), and others. It came out of melanotan research at the University of Arizona, originally as a "sunless tanning" idea. The net user-reported effect cluster is tanning + increased libido/erections + reduced appetite — though it's often used with UV/sunbed exposure, which compounds skin-cancer risk rather than replacing the sun.

Melanotan II vs PT-141 vs afamelanotide — get these straight

Three commonly confused melanocortin compounds, only two of which are approved:

Compound	What it is	Approval
Melanotan II	Unapproved tanning peptide (broad melanocortin)	Not approved anywhere
PT-141 / bremelanotide	Active metabolite of MT-II, developed for libido (MC4R)	FDA-approved (Vyleesi, 2019)
Afamelanotide ("Melanotan I")	MC1R-preferring photoprotection drug	FDA-approved (Scenesse, EPP)

So "Melanotan I" (afamelanotide / Scenesse) and PT-141 (Vyleesi) are real, approved drugs for specific conditions; Melanotan II is the unapproved tanning one. They are not interchangeable.

The risks — read this part

This is the load-bearing section. Melanotan II has a genuinely notable safety profile, and unlike most gray-market peptides it has drawn specific regulator warnings.

Common

Nausea — very common, especially with the first doses.
Facial flushing and fatigue.
Spontaneous erections / priapism in men (an MC4R effect; priapism can be a urologic emergency).
Decreased appetite and, of course, skin darkening (the intended effect).

The dermatologic concern (the important one)

Melanotan II darkens existing moles and can trigger new moles and freckles, and changes in mole size, shape and colour are documented in case reports. The serious problem: this can mask or complicate melanoma detection — the same darkening that's the "point" of the drug confounds the clinical screening that catches skin cancer early. There are melanoma case reports in users (causation isn't established — affected people usually had other risk factors like fair skin, sunbed use, or family history — but the concern is real, and it's why dermatologists advise mapping all moles before any use and watching for change).

Reported serious / rare

Rhabdomyolysis (muscle breakdown, ICU-level in one report), posterior reversible encephalopathy syndrome (PRES), and renal injury have all been reported, especially with prolonged use — plus the baseline contamination/sterility risk of an unregulated injectable. Long-term safety data simply don't exist in any rigorous form.

This is not a prescription, a dose, or a sourcing guide — and the risk here is real. Melanotan II is unapproved, regulators warn against it, and it carries a documented concern about mole changes that can hide melanoma, plus reports of priapism, rhabdomyolysis and worse. We are not prescribers and we do not recommend obtaining or using it. If you have used it, baseline and monitor your skin with a clinician, and seek care urgently for a prolonged erection.

The math

Melanotan II is sold as lyophilized powder reconstituted with bacteriostatic water and dosed in small milligram/microgram amounts — the same reconstitution arithmetic the peptide reconstitution calculator does. Worked example, purely as arithmetic (the doses are small, so concentration choice matters):

Vial label	10 mg lyophilized powder
Add	5 mL bacteriostatic water
Concentration	10 mg ÷ 5 mL = 2 mg/mL
Per 0.1 mL	0.2 mg — i.e. 10 units on a U-100 syringe = 0.2 mg
So 0.5 mg would be	0.25 mL = 25 units

Concentration is just milligrams divided by millilitres, and units are just hundredths of a millilitre on a U-100 insulin syringe. Because Melanotan II doses are small, a more dilute reconstitution gives larger, easier-to-measure draws. The reconstitution calculator converts vial size + water + target into exact syringe units. The milligrams above are illustrative arithmetic, not a recommended dose — commonly reported figures are around 0.25–1 mg, but Melanotan II is unapproved and there is no validated dose.

Tracking Melanotan II in OptiPin

If you are tracking Melanotan II, OptiPin treats it like any other entry — without endorsing it, and the most useful thing to track here is your skin:

Dose log + reminders — record each injection (with the loading/maintenance pattern) and get reminded on schedule, with site rotation.
Skin & mole notes / photos — log mole changes and side effects over time; baseline photos before any use are the dermatology-recommended safeguard given the melanoma-masking concern.
OptiInsight analysis — OptiPin's AI reads the full record (doses, symptoms) and surfaces what moved with what.
Supply tracking — log the reconstituted vial; OptiPin estimates remaining doses and an empty date.
Built-in reconstitution math — the small-dose conversion above is one tap in the app.

Track it properly

Log doses, skin notes & supply in OptiPin

Reminders, mole/skin notes, side-effect tracking, supply countdown, built-in reconstitution math, and OptiInsight analysis — all on-device. Baseline and watch your skin if you use a melanocortin compound.

Download on the App Store

FAQ

Is Melanotan II legal or approved?

No — not approved as a medicine anywhere. The FDA, UK MHRA, Australian TGA and Germany's BfArM have all warned against it. Sold unlicensed online with no guarantee of safety, purity or sterility; selling it as a medicine is illegal in many countries.

How does it work?

It's an α-MSH analog that activates melanocortin receptors. MC1R drives melanin production (tanning, often combined with UV); MC4R drives sexual arousal and appetite suppression.

What are the main risks?

Very common nausea, flushing, and priapism in men. The biggest concern is darkening/new moles that can mask melanoma; melanoma, rhabdomyolysis, kidney injury and PRES have been reported. Long-term safety data are limited.

vs PT-141 and afamelanotide?

Melanotan II is the unapproved tanning peptide. PT-141 (bremelanotide) is its metabolite, FDA-approved as Vyleesi for libido. Afamelanotide ("Melanotan I") is a separate approved drug (Scenesse) for erythropoietic protoporphyria. Not interchangeable.

Is it banned in sport?

Not confirmed to be explicitly named on the WADA list. But because it's not approved for human use, WADA's S0 "non-approved substances" catch-all could apply. Check the current WADA list and your authority; don't assume it's permitted.

Educational only, not medical advice. Melanotan II is unapproved and regulators (FDA, MHRA, TGA, BfArM) warn against it. It carries a documented concern about mole changes that can hide melanoma, plus priapism, rhabdomyolysis and other serious case reports. OptiPin does not recommend obtaining or using it. Baseline and monitor your skin with a clinician.

Sources

PT-141 (bremelanotide) · Peptides guide · Peptide reconstitution calculator · Side effects · Injection technique