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Melanotan II

Also known as Melanotan-2, MT-II, MT-2, MTII

Unapproved melanocortin agonist that tans the skin; reports of melanoma and systemic toxicity.

early-clinical Skin & cosmetic research chemical

At a glance

Category
Skin & cosmetic
Status
research chemical
Route
subcutaneous; on the grey market also intranasal
Half-life
approximately 30-60 minutes (human, subcutaneous); pigmentation persists far longer than the plasma level
Onset
First visible pigmentation after roughly 1-2 weeks; nausea and flushing within 1-2 hours of injection
Molecular weight
approximately 1024 g/mol
Sequence
Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2

Not approved for human use anywhere in the world, and regulators warn about it repeatedly. The UK position is worth stating precisely rather than as the usual slogan: the MHRA says it has 'repeatedly taken action to remove melanotan products so identified from sale for over 10 years', but also that a tanning product only counts as a medicine if it meets the definition in the Human Medicines Regulations 2012 — so injectable melanotan II products are not automatically medicines, and nasal tanning sprays making no medicinal claims will not generally be regulated as medicinal products at all 7. Between 2011 and 2021 the MHRA received 13 suspected adverse drug reaction reports associated with melanotan II through the Yellow Card scheme, a figure the agency itself notes is subject to unknown and variable under-reporting 7. It is sold online as a 'research chemical' or as an unregulated nasal spray, without any control over purity, dosage or sterility. Professional bodies of dermatologists explicitly advise against use.

Doping status: Not listed by WADA

Checked against the WADA 2026 Prohibited List. For a specific product and country, Global DRO is the lookup athletes are expected to use — the List names substances, not brand names.

Mechanism of action

Melanotan II is a cyclic analogue of alpha-MSH that binds non-selectively to melanocortin receptors: MC1R, MC3R, MC4R and MC5R. Because it is cyclic and contains a D-phenylalanine, it is broken down far more slowly than endogenous alpha-MSH and is considerably more potent.

Activation of MC1R on melanocytes increases eumelanin synthesis via cyclic AMP and the transcription factor MITF. The skin darkens as a result without UV exposure. However, melanotan II also acts on existing naevi and on melanocytes that already carry mutations — that is the core of the dermatological concern.

The lack of selectivity explains the rest of the side effect profile: MC4R activation in the hypothalamus causes appetite suppression, yawning, nausea and erections, while MC1R and MC3R effects on vascular tissue contribute to flushing and blood pressure changes. Melanotan II is, in other words, not a targeted pigmentation agent but a broadly acting melanocortin agonist.

What the research shows

Melanotan II was studied in humans in a handful of small phase 1 trials in the 1990s, after which development was halted; the derived, more selective bremelanotide was taken forward instead. There are no controlled studies of safety or efficacy for long-term cosmetic use. The human literature added since then consists almost entirely of case reports of harm.

Research in humans

In a double-blind crossover study in ten men with psychogenic erectile dysfunction (Wessells et al., 1998), 0.025 mg/kg subcutaneously produced a clinically observable erection in eight of the ten. A pilot phase 1 study confirmed an increase in pigmentation. After that there was no phase 2 or phase 3 programme. The later literature is anecdotal: melanotan-associated melanoma 2 and melanoma in situ 1, eruptive dysplastic naevi 4, rapid change in existing naevi 5, mucosal melanoma after use of a melanotan nasal spray 3, systemic toxicity with rhabdomyolysis and renal impairment, and renal infarction.

Animal and lab research

Animal models confirm that melanocortin agonists affect pigmentation and sexual behaviour. They say nothing about melanoma risk with long-term use in humans, which is precisely the most important open question.

Caveats. There is not a single long-term study. The causal link between melanotan II and melanoma is not proven in the sense of an epidemiological study — but that is a consequence of the absence of research, not of reassuring data. The known biology (stimulation of melanocytes, including atypical ones), the number of independent case reports and the strong association with concurrent sunbed use 45 make the signal serious enough that it cannot be ignored. On top of that, the product itself is uncontrolled: the content, purity and sterility of vials sold online have not been established.

What it is used for

  • Cosmetic tanning of the skin without, or with limited, UV exposure — the reason it is actually used, without any registration anywhere 7
  • Historically investigated for erectile dysfunction; that line was continued with bremelanotide (PT-141) 6
  • Appetite suppression — a side effect via MC4R, not studied as a treatment

Dosing

Dose
No validated dosing schedule. Doses of 250-1000 micrograms per administration circulate in user protocols
Frequency
In user protocols: daily to several times a week during a 'loading phase', then 1-2x per week for maintenance
Route
subcutaneous; intranasal use occurs but offers no dose control whatsoever
Duration
Not established
  • The doses above are descriptive and come from user protocols, not from clinical studies. No validated dosing schedule exists, because there is no approved indication.
  • The only well-documented human dose is 0.025 mg/kg subcutaneously, from the 1998 erection study, in which nausea, yawning and reduced appetite occurred 6. That is a per-kilogram figure: for a 70 kg adult it works out at roughly 1.75 mg, which is well above the 250-1,000 microgram doses that circulate among users. The two figures are not the same kind of number and cannot be compared without doing that arithmetic.
  • The reported rhabdomyolysis case involved a 39-year-old man who injected 6 mg of internet-purchased melanotan II at once — roughly six to twenty-four times the circulating per-injection doses, and about three times the single study dose for a 70 kg adult. Within two hours he was tachycardic to 146 bpm with mydriasis, diaphoresis and tremor; creatine kinase peaked at 17,773 IU/L and creatinine at 2.25 mg/dL, and he spent three days in intensive care 8. Illustrative of what goes wrong without pharmaceutical control.
  • Grey-market nasal sprays do not deliver a reliable dose and have been linked to mucosal abnormalities at the site of administration.

These figures describe what the literature and published protocols report. They are not advice and not a dosing instruction.

Protocols

Loading and maintenance pattern

user protocol — not validated

Source: Pattern circulating among users and sellers

This is not a validated schedule. It is a pattern that circulates among users and sellers, reproduced because it is what people actually follow — not because it has been tested. No trial established these doses, this interval or this duration, and nobody is checking what is in the vial. Treat every number below as an assertion, not a finding.

Loading phase250 to 1,000 mcg subcutaneously, daily or several times a week, until the desired pigmentation appears
Maintenancethe same dose once or twice weekly
Throughoutultraviolet exposure continued, since the pigmentation depends on it

The specific hazard is not the dose but what the pattern requires: continued UV exposure while every existing mole darkens, which is exactly the change that would otherwise send someone to have a lesion examined. Melanoma has been reported in users, including at the site of nasal spray use. The only well-documented human dose is 0.025 mg/kg from a 1998 study, which is about 1.75 mg for a 70 kg adult and therefore not directly comparable with the microgram figures above; a single 6 mg self-injection produced rhabdomyolysis.

Schedules are reproduced as their source states them. Units, IU and milligrams explains why the figures are not interchangeable between products.

Reconstitution

Vial sizes
10 mg
Solvent
bacteriostatic water (0.9% benzyl alcohol)
Storage
Reconstituted 2-8 °C, usually for a few weeks. Powder in the freezer, protected from light.

Worked example

10 mg vial + 2 ml bacteriostatic water = 5 mg/ml. 500 micrograms corresponds to 0.1 ml, that is 10 units on a U100 insulin syringe.

These worked examples are purely descriptive. They change nothing about the fact that the starting material is not pharmaceutically controlled: the content, purity and endotoxin level of vials sold online are unknown.

Work it out for Melanotan II

Safety

Side effects

  • Change in existing moles and the appearance of new, partly dysplastic naevi — described repeatedly, sometimes within weeks of a short course
  • Melanoma: there are multiple independent case reports of melanoma and melanoma in situ arising during or shortly after use, including a mucosal melanoma in the upper jaw after use of a melanotan nasal spray. Dermatologists warn explicitly against use, because the substance can push premalignant melanocytic lesions towards further degeneration
  • Nausea and vomiting — very common, particularly in the first hours after injection; nausea was among the effects seen at the one well-documented study dose 6
  • Priapism and unwanted spontaneous erections; there are cases that required emergency treatment, including a published report of priapism after melanotan II overdose 10
  • Rhabdomyolysis with renal impairment and systemic, sympathomimetic toxicity — described after a single 6 mg self-injection, with creatine kinase peaking at 17,773 IU/L and three days of intensive care 8
  • Renal infarction — described in a 2020 case report of a man who had taken 27 mg of melanotan II over six months, in whom CT showed roughly half of one kidney infarcted; the authors consider both a thrombotic effect and direct toxicity to the renal parenchyma 9
  • Flushing, raised blood pressure, tachycardia
  • Strong appetite suppression and weight loss
  • Darkening of the lips, gums, nipples and scars; uneven pigmentation and persistent hyperpigmentation
  • Yawning, fatigue, headache, dizziness
  • Infection, abscess or injection site reactions from non-sterile material
  • Pyoderma gangrenosum has been linked to melanotan use in one case

Do not use if

  • Personal or family history of melanoma or of skin cancer — absolutely inadvisable; melanoma and melanoma in situ have been reported in users 12
  • Dysplastic naevus syndrome, FAMMM syndrome or a CDKN2A mutation: in this group, an eruption of dysplastic naevi has been described in a teenager after melanotan injections combined with sunbed use 5
  • Many moles, atypical naevi or fair, freckled skin — eruptive dysplastic naevi have been described following melanotan use 4
  • Pregnancy and breastfeeding
  • Cardiovascular disease, arrhythmias or hypertension — the documented toxicity picture is sympathomimetic, with tachycardia to 146 bpm and raised blood pressure after a single high dose 8, and the renal infarction case involved a previously normotensive man found at 165/95 mmHg 9
  • Renal impairment — both acute kidney injury 8 and renal infarction 9 have been reported after use
  • Concurrent sunbed use or intensive UV exposure: melanotan II offers no reliable protection against UV damage and the combined use recurs in several melanoma cases 45
  • There is in fact no group in which dermatologists consider this agent justifiable; the points above mark where the risk is raised even further

Interactions

Not systematically studied. Combination with PDE5 inhibitors (sildenafil, tadalafil) increases the risk of priapism and of a drop in blood pressure; priapism has been reported after melanotan II alone, without any co-administered drug 10. Combination with stimulants or sympathomimetics can increase cardiovascular strain, and melanotan II on its own has produced a sympathomimetic toxidrome with tachycardia, mydriasis, diaphoresis and tremor 8. Concurrent use with UV exposure or photosensitising drugs is particularly undesirable from a dermatological point of view.

Common questions

What is melanotan II?
An unapproved synthetic melanocortin agonist marketed to tan the skin (through the MC1R receptor). The libido and erection effects it is discussed for are a side effect of its action at a second receptor, MC4R.
Is melanotan II safe?
It is not an approved drug, and there are documented concerns — nausea, darkening and changes to moles, reports of melanoma, and spontaneous erections (priapism). It is sold as an unregulated research chemical of unknown purity. This site does not recommend its use.
What is the difference between melanotan I and melanotan II?
Melanotan I (afamelanotide) is a more selective, approved drug for a rare light-sensitivity condition; melanotan II is the unapproved, broader-acting version sold for cosmetic tanning.
How does melanotan II compare with PT-141?
PT-141 is an approved drug for sexual desire; melanotan II is an unapproved tanning peptide whose sexual effects are incidental. See PT-141 vs melanotan II.

Sources