Melanotan-2 at a glance
Melanotan-2, which papers and the shop write as Melanotan II or MT-II, is a cyclic heptapeptide modelled on alpha-melanocyte-stimulating hormone (alpha-MSH). A lactam bridge closes its ring. In the 1980s a group at the University of Arizona, Mac Hadley (physiology), Victor Hruby (chemistry) and Robert Dorr (pharmacology), asked whether skin pigment could be raised without ultraviolet exposure, on the reasoning that this might lower the risk of skin cancer. No study has ever demonstrated that it does.
Their first compound, melanotan I, was a linear chain. Melanotan-2 came afterwards as a smaller ring that was more potent in laboratory assays and held up longer against enzymes. It never finished a development programme. This profile reports what studies found and does not describe use in people.
- Cyclic heptapeptide, 1024.2 Da, agonist at MC1R, MC3R, MC4R and MC5R.
- Human data: two small studies from the 1990s, plus case reports of harm.
- Not approved as a medicine anywhere; the subject of public warnings by European medicines regulators.
How Melanotan-2 works
Five melanocortin receptors exist. Pigment cells carry MC1R, which switches on production of dark eumelanin. The adrenal gland responds to ACTH through MC2R. In the brain, MC3R and MC4R help to regulate energy balance and appetite, and MC4R is involved in sexual function as well. Exocrine glands express MC5R.
Melanotan-2 activates four of the five: MC1R, MC3R, MC4R and MC5R. One exposure thus reaches pigment cells, appetite circuits and sexual pathways together. This lack of selectivity defines the molecule, and it shaped what came next. Erections that nobody had anticipated in the first volunteers started a separate research line, which ended in bremelanotide, profiled here as PT-141.
The appetite effect runs opposite to that of ghrelin-receptor agonists such as GHRP-6, which stimulate feeding. The fact-checked material behind this profile gives no half-life for Melanotan-2, so none appears here.
The evidence ladder for Melanotan-2
| Evidence level | Model or trial | Main finding |
|---|---|---|
| Animal study | Several mouse models of overeating; Fan et al., Nature, 1997 | Delivery into the brain ventricles suppressed feeding, a result that made MC4R a central target in appetite research |
| Human pharmacology (pilot phase I) | Three healthy men; Dorr et al., Life Sciences, 1996 | Two of the three showed more pigmentation of face, upper body and buttocks, which could still be measured one week after the last dose; also recorded: spontaneous erections of one to five hours, stretching and yawning, mild nausea at most dose levels, somnolence at the top dose |
| Small controlled human study | Ten men whose erectile dysfunction had no known organic cause; Wessells et al., Journal of Urology, 1998; double-blind crossover with placebo | Clinically apparent erections in eight of ten; tip rigidity above 80% lasted 38 minutes on average, compared with 3 minutes after placebo; reduced appetite, yawning and nausea were more common on the peptide |
The human rungs of this ladder are short. A study in three volunteers is a tolerability exercise and says nothing reliable about efficacy or safety. The crossover study was controlled, but it had ten participants. The sources describe no larger controlled study; the rest of the human literature is case reports. There is no licensed use at the top.
The animal rung is where Melanotan-2 earned its place: it is still a routine tool for probing central melanocortin signalling, which does not make it a drug candidate.
Melanotan-2 doses reported in studies
The table lists reference values from published work and is not guidance. Melanotan-2 has no approved human use anywhere and therefore no validated dose.
| Setting | Dose | Schedule | Note |
|---|---|---|---|
| Three healthy men (Dorr et al., 1996) | Escalated from 0.01 mg/kg in steps of 0.005 mg/kg to 0.025–0.03 mg/kg | Two weeks, with peptide or saline given on alternate weekdays | Subcutaneous; the escalation ended where side effects appeared |
| Ten men with erectile dysfunction (Wessells et al., 1998) | 0.025 mg/kg | Placebo crossover | Instrumented monitoring |
Safety findings and open questions
Two sources feed the safety record: the 1990s studies and reports of harm after unsupervised use. Nausea was the most consistent finding in the controlled work, with yawning, stretching and reduced appetite alongside it. Through MC4R the peptide can cause erections in the absence of sexual stimulation, and overdose has been linked to priapism, which is a medical emergency.
The case literature is more serious. A 2012 report describes a man who developed rhabdomyolysis, kidney dysfunction and a heart rate that peaked at 146 beats per minute after a single self-administered 6 mg dose. Existing moles have darkened and new ones have appeared in users, and cases of melanoma have been published.
- Does Melanotan-2 raise long-term skin risk? A case report proves no causal link, so the matter is open in both directions.
- What does repeated exposure over months or years do? No study has looked.
- What do unlicensed products actually contain? Regulators cite uncertain content as one reason for their warnings.
Bench notes: storing and reconstituting Melanotan-2
Melanotan-2 is handled as a lyophilised powder, and the data panel gives −20 °C for storage. Keep the vial closed, dry and shielded from light, and let it come to room temperature before opening.
For reconstitution, laboratories normally use bacteriostatic water. Let the solvent run down the inner wall of the vial, swirl gently and avoid shaking. Store the solution in the refrigerator and work from aliquots, since repeated freezing and thawing degrades peptides. Details are in the storage and reconstitution protocol.
Status in the Netherlands, Belgium and Luxembourg
No country has authorised Melanotan-2 as a medicine. Marketing authorisations issued through the European Medicines Agency apply in the Netherlands, Belgium and Luxembourg alike, and for this compound there is none. Several European medicines regulators have issued public warnings about unlicensed melanotan injections and nasal sprays. The medicines agency of the UK is one of them and the former Irish Medicines Board, today called the HPRA, is another; both point to unknown side effects and uncertain product content.
Under EU law a substance of this kind is a medicinal product and needs an authorisation, so whatever is offered in Europe is a research chemical and nothing more. Possession and personal import are regulated country by country, and institutions have rules of their own; check them before you order. The primer on research peptides sets out the difference between a medicine and research material.
Compare afamelanotide. The former melanotan I, a linear molecule, received its EU authorisation in 2014 under the name Scenesse. The implant is meant for adults who have erythropoietic protoporphyria, a hereditary condition that makes sunlight severely painful, and specialist porphyria centres prescribe it. Melanotan-2 has no controlled trial programme of that kind behind it. In sport, section S0 of the WADA Prohibited List bans every pharmacological substance that has no approval for human therapeutic use, and Melanotan-2 fits that description exactly.
Ordering Melanotan-2 for research in the Benelux
King Peptides lists the compound as Melanotan II 10 mg, for laboratory research. On the certificate of analysis for your lot, confirm that HPLC purity is 99% or higher, that the lot number equals the one on the vial, and that the mass spectrum matches 1024.2 Da. Bremelanotide comes in at 1025.2 Da, roughly 1 Da higher, so a rounded mass cannot distinguish the two; a properly resolved spectrum can. Each lot has its own certificate with HPLC and mass spectrometry data. The guide to checking a certificate of analysis covers the remaining lines.
Dispatch is from the Netherlands, in a tracked parcel. Transit is usually 1–2 business days inside the Netherlands and 3–5 business days to Belgium and Luxembourg, and there is no customs clearance because the shipment stays within the EU. See buying research peptides in the Benelux for the full supplier checklist.
Melanotan-2: quick answers
Is Melanotan-2 a licensed medicine anywhere? No. The licensed relative is afamelanotide, a different, linear molecule.
What have regulators said about it? Several European medicines regulators have publicly warned against unlicensed melanotan products, because side effects are unknown and contents uncertain.
How many people took part in the controlled studies? Three healthy men in the 1996 pilot and ten men in the 1998 crossover study.
How is it told apart from PT-141 on a certificate? By about 1 Da. Melanotan-2 is 1024.2 Da and bremelanotide 1025.2 Da, which only a well-resolved mass spectrum shows.
Research use only. This page describes Melanotan-2 for laboratory and scientific research. Research material has no marketing authorisation, whatever the status of the molecule as a medicine elsewhere, and is not meant for human or veterinary use. Nothing on this page is medical advice; the doses above are those reported in published studies, not recommendations. Check the rules that apply in your country and at your institution before ordering.