Melanotan II (MT-II)
Also known as: Melanotan 2, MT-2, MT-II, MTII, Melanotan II, Barbie Drug
Non-selective melanocortin agonist used for tanning and libido — and the substance where an unmonitored effect on moles carries a genuine, underestimated risk.
Substance family
Peptides used for tendon, gut and skin repair. Mechanisms are described and animal data exists; controlled human trials for these applications largely do not.
Effects on
Which outcomes this substance acts on — descriptive, not a recommendation.
Strain profile
Where this substance is most likely to hit — a rough orientation, individually dependent on dose, duration and predisposition.
This substance causes
Dosing & protocols by goal
Rough orientation ranges as reported in harm-reduction literature — not an individual treatment plan. Doses are individual and open-ended; frequency depends on the ester or half-life.
Loading phase (tanning)
ExperimentalDose
250–500 µg / day
Frequency
1× daily, subcutaneous
Cycle length
1–2 weeks until the desired pigmentation
Start at the low end. Nausea and flushing are dose-dependent and considerably worse at the start; a higher first dose reliably produces them.
Maintenance
ExperimentalDose
250–500 µg
Frequency
1–2× / week
Cycle length
Varies
Far less is needed once the pigmentation is established. Continuing at loading doses only increases the side effects.
Libido (off-label use of the effect)
ExperimentalDose
250–1000 µg as needed
Frequency
Occasional
Cycle length
—
The erectile effect runs through MC4R and is the reason bremelanotide, a related substance, was approved for a sexual dysfunction indication. Nausea at these doses is common.
Side effect & countermeasure
Typical problems and what you can do to reduce harm — at a glance. Does not replace medical monitoring.
Problem
Darkening and change of existing moles
Countermeasure
The most serious risk of this substance and the reason medicines agencies warn about it. Melanotan darkens existing naevi and can make new ones appear — which masks exactly the visual changes used to detect melanoma early. Have a dermatologist document your moles before starting and check them afterwards. Anyone with many naevi or a family history of melanoma should not use it.
Problem
Nausea and flushing, especially at the start
Countermeasure
Dose-dependent and strongest with the first injections. Start at 250 µg or lower, inject in the evening, take with food. It usually subsides after a few days; if it does not, the dose is too high.
Problem
Spontaneous erections and unwanted sexual side effects
Countermeasure
Runs through MC4R and is not separable from the tanning effect — both come from the same non-selective receptor binding. Lower doses reduce it; the melanotan I variant lacks this effect entirely.
Problem
Darkening of skin areas that were not the target
Countermeasure
Pigmentation is not uniform. Freckles, scars and existing dark areas darken disproportionately, and the effect can persist for months after stopping.
Problem
No safety data and grey-market quality
Countermeasure
There are no clinical trials on long-term use. Everything in circulation is research-grade material of unverified purity. Only sources with an independent HPLC/MS analysis — sterility matters here because it is injected.
Problem
Elevated blood pressure
Countermeasure
Melanocortin receptors are involved in cardiovascular regulation. Measure blood pressure; relevant for anyone already elevated.
Overview
Melanotan II is a synthetic analogue of alpha-MSH, the hormone that stimulates pigment production in the skin. It was originally developed at the University of Arizona as an approach to skin cancer prevention — the idea being that a tan induced without UV exposure would protect against sun damage.
That research direction produced two substances. Melanotan I became a licensed medicine for a rare disease. Melanotan II did not, because its non-selective receptor binding produces effects far beyond pigmentation.
It is used for tanning and, secondarily, for its effect on libido. Its most significant risk has nothing to do with either.
Mechanism of Action
Melanocortin receptors exist in several subtypes with quite different functions. MC1R sits in the pigment cells of the skin and controls melanin production. MC3R and MC4R are involved in appetite regulation, sexual function and cardiovascular control.
Melanotan II binds all of them. This is the source of both its effect profile and its problem: the tanning, the nausea, the appetite suppression and the erectile effect all come from the same non-selective binding and cannot be separated by dosing.
Pigmentation occurs without UV exposure, which was the original point. But it does not occur uniformly — existing pigmented areas respond more strongly, which is why freckles, scars and moles darken disproportionately.
That last effect is the one that matters most. Melanocytic naevi — moles — darken and can enlarge, and new ones can appear. Early melanoma detection relies entirely on noticing visual change in moles. A substance that changes all of them simultaneously removes the signal that detection depends on. Several European medicines agencies have issued warnings on exactly this basis.
Typical Context
Melanotan II is used in a loading phase of one to two weeks at two hundred and fifty to five hundred micrograms daily, followed by maintenance dosing once or twice weekly.
Starting low genuinely matters here, and not for the usual reasons. Nausea and facial flushing are strongly dose-dependent and worst with the first injections; a high starting dose reliably produces several unpleasant hours. Evening injection with food is the practical answer.
The erectile effect is often described as a bonus and is worth understanding as what it is: a consequence of MC4R binding that cannot be dialled out. The related compound bremelanotide was developed specifically for this effect and holds an approval for a sexual dysfunction indication — which shows the effect is real and pharmacologically substantial rather than incidental.
Before any of this, the mole question deserves a decision rather than an afterthought. Having a dermatologist document existing naevi before starting is the one measure that preserves the ability to detect a change later. Anyone with many moles or a family history of melanoma is choosing a substance whose main risk lands exactly where their baseline risk already is.
Side Effects & Risks
- Darkening, enlargement and new appearance of moles — the leading risk
- Masking of visual changes relevant to early melanoma detection
- Nausea, vomiting, facial flushing, especially at the start
- Spontaneous erections, altered libido
- Uneven pigmentation; freckles and scars darken disproportionately
- Appetite suppression
- Elevated blood pressure
- No safety data on long-term use; grey-market quality only
Blood Work & Monitoring
There is no specific lab marker. What matters here is not blood work but dermatology:
- Dermatological mole documentation — before starting and at regular intervals; the essential measure with this substance
- Blood pressure — measured at home
- Complete blood count — as a baseline
Harm-Reduction Notes
- Have moles documented by a dermatologist before starting; this is the one measure that matters most
- Not for anyone with many naevi or a family history of melanoma
- Start at 250 µg or lower, inject in the evening with food — nausea is worst at the beginning
- Sexual side effects cannot be separated from the tanning effect; both come from the same binding
- Pigmentation persists for months after stopping
- The substance does not replace sun protection; pigmentation induced this way is not equivalent to full UV protection
- Only sources with an independent analysis; sterility matters since it is injected
Legal status by region
Regulation differs considerably between jurisdictions and changes over time. This is a rough orientation, not legal advice — check the rules that apply where you are.
| Region | Regulatory status |
|---|---|
| United States | Not approved for human useSold as a research chemical; marketing for human consumption is unlawful. |
| EU / UK | No marketing authorisationNeither a medicine nor a supplement — no legal route for human use. |
| Most other jurisdictions | Unregulated grey areaPossession is legal in many places precisely because no framework covers it. That is not an indication of safety. |
| Competitive sport | ProhibitedListed by WADA where a relevant class applies. |