What Is Melanotan-2? The Melanocortin Peptide, Its Relatives and the Safety Literature
Melanotan-2 (MT-II) is a synthetic cyclic heptapeptide modelled on alpha-melanocyte-stimulating hormone (alpha-MSH) that activates several melanocortin receptors at once. A University of Arizona group reported a pilot human study in 1996, with increased pigmentation and unwanted effects in the volunteers. Melanotan-2 itself has no approved medical use. Two related molecules do: afamelanotide and bremelanotide. Dermatology reviews link unregulated use to changes in moles and warn about unregulated supply.
This page does not recommend human use. The safety literature is case reports and reviews, which show association, not proven cause. The 1996 pilot study had three volunteers. Research context only; nothing here is medical guidance.
At a glance
| Melanotan-2 (MT-II) | |
|---|---|
| Structure | Lactam-bridged cyclic heptapeptide, Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2, derived from alpha-MSH residues 4–10 |
| Molecular weight | About 1,024 Da |
| Targets | Melanocortin receptors, non-selectively (for example MC1R on pigment cells and MC4R in the brain) |
| Developed by | University of Arizona; a pilot Phase I study was reported in 1996 |
| Approval | No approved medical use |
The melanocortin family: MT-2 and its relatives
Alpha-MSH is a natural 13-residue hormone. Several synthetic analogues were built from it, and they are easy to confuse:
| Molecule | What it is | Status |
|---|---|---|
| Afamelanotide (Melanotan-1) | A linear alpha-MSH analogue | Authorised for erythropoietic protoporphyria, a rare light-intolerance disorder; Habbema et al. (2017) called it the only alpha-MSH analogue approved at that time, for a limited number of indications |
| Melanotan-2 | A cyclic, non-selective analogue | No approved use |
| Bremelanotide (PT-141) | A related cyclic heptapeptide studied for its central (brain-mediated) effects | Marketed in the US as Vyleesi for hypoactive sexual desire disorder in premenopausal women; the Phase 3 trials are Kingsberg et al. (2019) |
The authorisation for afamelanotide covers the licensed medicinal product (Scenesse). Research-grade peptide sold under the Melanotan-1 name is not that medicine and carries no authorisation.
The difference matters. The approved molecules were developed under trial programmes with defined populations and manufacturing standards. The safety evidence for afamelanotide does not transfer to Melanotan-2. For the bremelanotide side see PT-141 (bremelanotide).
The human pilot data
The earliest human data are small and from one group:
- Pilot Phase I (Dorr et al., 1996). Three healthy male volunteers took part in a single-blind, placebo-controlled study. Two showed increased pigmentation of the face, upper body and buttock a week after administration ended. Mild nausea was reported at most dose levels, one volunteer had grade II somnolence and fatigue at the higher dose, and a stretching and yawning complex correlated with spontaneous erections experienced intermittently over one to five hours after administration.
- Central effects (Wessells et al., 1998). A small double-blind crossover study in 10 men recorded erectile responses together with transient nausea, stretching, yawning and decreased appetite. These are brain-mediated effects, and this line of work is part of the background to bremelanotide rather than to any approved use of Melanotan-2.
Both studies came from the same research group, and neither was designed to establish safety over time.
What the safety literature says
The safety literature is written by dermatologists who see the consequences of unregulated supply. The 2017 review in the International Journal of Dermatology (Habbema et al.) is a useful summary:
- There are open questions about the preparation, administration and dosage of the unregulated products.
- Case reports increasingly link unregulated melanotan use to changes in existing moles and newly emerging dysplastic naevi.
- Four case reports described melanomas emerging from existing moles during or shortly after melanotan use. The review stresses that conclusive evidence linking the two is lacking.
- Multiple national health organisations have issued safety warnings about melanotan I and II.
Individual reports include a single case of new atypical naevi and darkening of existing ones in a man with a prior melanoma history who self-administered a synthetic alpha-MSH peptide, with the naevi lightening after he stopped (Cardones & Grichnik, Arch Dermatol, 2009); the first two Swedish cases of eruptive naevi after products marketed as melanotan II (Burian et al., 2013); and an Australian dermatology letter on the public-health interest (Adler et al., 2017). For how the Nordic melanoma picture fits around this, see Sweden, melanoma and Melanotan-2.
What this means for research material
Melanotan-2 is sold here as laboratory research material only. For any batch, identity rests on a cyclic, lactam-bridged structure of about 1,024 Da, and a linear peptide of the same residues weighs about 18 Da more, so the mass is informative; purity should be reported with the method. The Melanotan-2 COA page carries the published certificate, and how to read a certificate of analysis explains what each line does and does not show.
Nothing on this page should be read as a suggestion to use Melanotan-2 in people. The regulatory position is that it has no approved use, and the warnings above come from dermatology and health authorities.
Research takeaway
- Melanotan-2 is a cyclic, non-selective melanocortin agonist with no approved use.
- Afamelanotide and bremelanotide are separate molecules with their own trial programmes; their evidence does not transfer to it.
- The 1996 pilot study had three volunteers; the safety literature is case reports and reviews.
- Dermatology reviews associate unregulated use with mole changes and describe four melanoma case reports, without proven causation.
Primary sources
- Life Sciences — Evaluation of melanotan-II, a superpotent cyclic melanotropic peptide in a pilot phase-I clinical study (Dorr et al., 1996)
- Journal of Urology — Synthetic melanotropic peptide initiates erections in men with psychogenic erectile dysfunction: double-blind, placebo controlled crossover study (Wessells et al., 1998)
- International Journal of Dermatology — Risks of unregulated use of alpha-melanocyte-stimulating hormone analogues: a review (Habbema et al., 2017)
- Archives of Dermatology — alpha-Melanocyte-stimulating hormone-induced eruptive nevi (Cardones & Grichnik, 2009)
- Läkartidningen — Eruptive nevi after injection of drugs marketed as melanotan II: the first two Swedish cases (Burian et al., 2013)
- Australasian Journal of Dermatology — The unregulated use of melanotan-II is of public health interest to Australian dermatologists (Adler et al., 2017)
- Obstetrics & Gynecology — Bremelanotide for the Treatment of Hypoactive Sexual Desire Disorder: Two Randomized Phase 3 Trials (Kingsberg et al., 2019)
Melanotan-2 as laboratory research material
New-U lists Melanotan-2 as laboratory research material. The studies above describe published human pilot data and dermatology case reports, not this material, and New-U does not suggest use in people. Research use only – all claims made on this site are for testing and research use only.
View Melanotan-2Frequently asked questions
What is Melanotan-2?
Melanotan-2, or MT-II, is a synthetic cyclic heptapeptide modelled on alpha-melanocyte-stimulating hormone. It activates several melanocortin receptors rather than one, and it has no approved medical use.
Is Melanotan-2 the same as Melanotan-1?
No. Melanotan-1 is afamelanotide, a linear alpha-MSH analogue whose licensed medicinal product (Scenesse) is authorised for erythropoietic protoporphyria; research-grade peptide sold under the Melanotan-1 name is not that medicine. Melanotan-2 is a different, cyclic and non-selective molecule with no approved use, and the safety evidence for afamelanotide does not transfer to it.
Is Melanotan-2 approved?
No. It has no approved medical use. The related molecules afamelanotide and bremelanotide are authorised for specific conditions after their own trial programmes.
Is Melanotan-2 the same as PT-141?
No. PT-141 is bremelanotide, a related cyclic heptapeptide that is marketed in the US as Vyleesi for one condition. Melanotan-2 is a different molecule that acts on several melanocortin receptors and is not approved.
What risks does the literature describe?
A 2017 dermatology review describes changes in existing moles and newly appearing dysplastic naevi with unregulated use, four case reports of melanomas emerging from existing moles, and safety warnings from national health bodies. It stresses that conclusive evidence of cause is lacking.
External links are provided for research reference only; New-U is not affiliated with the cited organisations or authors. All figures are published study results shown for research context, not dosing guidance. New-U Research Compounds supplies research compounds strictly for laboratory research use only — not for human consumption.
Part of the Skin & cosmetic research research area — explore related compounds, guides and sources.