Melanotan-2
Also known as MT-2, MT-II, Melanotan II, Cyclic alpha-MSH analog
Melanotan-2 is a cyclic alpha-MSH analog that darkens skin quickly and also boosts libido and suppresses appetite because it hits several melanocortin receptors at once. It is the most widely used tanning peptide and the one with the most side effects.
Overview
Melanotan-2 came out of the same University of Arizona program that produced melanotan-1. Researchers shortened the peptide to seven amino acids and cyclized it with a lactam bridge, which made it smaller, more stable, and more potent. Unlike melanotan-1, which is selective for the MC1R receptor on skin, melanotan-2 is a broad agonist across MC1R, MC3R, MC4R, and MC5R. That broad activity is why early human studies reported not only tanning but also spontaneous erections, yawning, stretching, and reduced appetite. The erection finding directly led to the development of PT-141.
Human data comes from a handful of small studies in the 1990s. Volunteers given melanotan-2 subcutaneously for a week or two developed noticeable darkening, especially on the face, arms, and neck, with the effect greatest in fair skinned people. Men with erectile dysfunction had improved erections in a small placebo controlled trial. Nausea and vomiting were common, along with flushing, fatigue, and appetite loss. Development as a drug was abandoned in favor of melanotan-1 for pigmentation and PT-141 for sexual function, and melanotan-2 has existed since as a grey market product.
It is popular because it works fast, is cheap, and the extra effects on libido and appetite are often welcome. The concerns are real though. Nausea at the start is nearly universal. Darkening of moles and the appearance of new ones is reliably reported and has prompted case reports of melanoma diagnosed in users, though causation has not been established. Regulators in the UK, Australia, and elsewhere have warned against it. There is no long term safety data of any kind, and product quality is a lottery. Melanotan-1 is the better choice for anyone who wants the tan without the rest.
How it works
Melanotan-2 activates melanocortin receptors throughout the body. At MC1R on melanocytes it raises cAMP and drives tyrosinase to produce eumelanin, darkening the skin. At MC4R in the hypothalamus it increases sexual motivation and produces erections through central pathways, the same mechanism as PT-141, and it suppresses appetite through the same receptor, which is the pathway that anti-obesity melanocortin drugs like setmelanotide target. MC3R activation contributes to energy balance effects. The cyclic structure protects the peptide from breakdown and improves receptor binding, so effects last several hours from a single dose. The nausea and yawning appear to come from central melanocortin signaling in the brainstem.
What the research shows
- human pilotSubcutaneous melanotan-2 for 2 weeks produced significant skin darkening in healthy men, most pronounced on the face and neck.
- human RCTMelanotan-2 improved erectile function in men with psychogenic erectile dysfunction in a small placebo controlled crossover trial.
- human pilotNausea, stretching, yawning, and reduced appetite were reported at doses effective for tanning.
- rodentMC4R agonism reduces food intake and body weight in rodent models of obesity.
- human pilotCase reports describe new or changing melanocytic lesions, including melanoma, in melanotan-2 users, without established causation.
Evidence labels: rodent and in vitro mean no human data for that finding. Human pilot means small, often uncontrolled. Human RCT means randomized and controlled. Clinical means an approved drug with regulatory data.
Dose calculator
U-100 insulin syringeUnits are a volume on the syringe, not an amount of peptide. Concentration changes every time you change the water volume. The standalone calculator explains the math.
Dosing and protocol
start at 0.25 mg to test nausea response; 0.5 mg daily is a typical loading dose
2-3 week loading phase, then maintenance as desired
Evening is common so the nausea passes during sleep. Some UV exposure a few times a week is needed to develop the tan.
| Vial | Suggested water | Concentration | Low dose draw |
|---|---|---|---|
| 10 mg | 2 mL | 5 mg/mL | 5 units |
Lyophilized: freezer or fridge, away from light. Reconstituted: fridge 2-8C, use within 4 weeks.
Cautions
- ▲Nausea and sometimes vomiting, especially for the first several doses; start very low and dose at night.
- ▲Darkens existing moles and freckles and can produce new ones; melanoma has been reported in users, so document your skin and get any changing mole checked.
- ▲Spontaneous erections, increased libido, and reduced appetite are expected and can be unwelcome.
- ▲Flushing, fatigue, yawning, and stretching are common; a small blood pressure rise is possible.
- ▲Unregulated product; several health authorities have issued warnings, and contamination and mislabeling are documented.
Commonly stacked with
Frequently asked
How do I minimize the nausea?
Start at 0.25 mg or less, inject in the evening on a light stomach, and stay at that dose until the nausea fades before increasing. Most people adapt within a week. Antihistamines or ondansetron help if it is bad. If it never settles, switch to melanotan-1.
Why are my moles getting darker?
Because the peptide stimulates every melanocyte in your body, and moles are clusters of melanocytes. This is expected and usually reverses after stopping, but it makes monitoring for melanoma harder. Take photos before starting and see a dermatologist about anything that changes shape, size, or has irregular borders.
Will it make me lose weight?
It reduces appetite through the same brain receptor that obesity drugs like setmelanotide target, so many people eat less, especially early on. It is not a reliable weight loss tool and the effect fades, but it is noticeable enough that some people use it partly for that reason.
Is it legal?
In most countries it is not approved for sale as a medicine and is sold as a research chemical. The UK, Australia, and several EU countries have issued specific warnings. Possession is generally not a crime but selling it as a tanning product is.
References
- Melanotan-II, a cyclic alpha-MSH analog, induces tanning in human volunteers. Journal of Clinical Endocrinology and Metabolism, 1996
- Double blind, placebo controlled evaluation of melanotan-II in men with psychogenic erectile dysfunction. Journal of Urology, 1998
- Melanotan-associated melanoma and changing melanocytic naevi: case reports and review. British Journal of Dermatology, 2009