Summary
Melanotan II is a synthetic cyclic peptide developed at the University of Arizona in the 1990s as a sunless tanning agent. It activates several melanocortin receptors, causing skin darkening, appetite loss and erections. It has never been approved, and dermatologists have reported changes in moles and cases of melanoma in users.
Structure
Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2. A cyclic analog of α-MSH.
How it works
MT-II activates MC1R (pigmentation), MC3R and MC4R (appetite, sexual function) without selectivity, which is why its effects are broad and its side effects frequent.
Research use cases
Areas where Melanotan II has been studied. Inclusion here does not mean it works for that purpose.
- Tanning and photoprotection (historical research)
- Erectile dysfunction (early trials)
- Appetite and obesity models
What the research found
Phase 1 pilot
In a small pilot study, MT-II darkened skin in healthy men at low doses, with nausea, flushing and spontaneous erections as common side effects.1
Erectile function
In a double-blind crossover study of men with psychogenic erectile dysfunction, MT-II induced erections in most participants, which led to the development of bremelanotide.2
Unregulated use
A review of unregulated MSH-analog use documented new and changing pigmented moles, eruptive naevi and melanoma reports, as well as products of uncertain content.3
Safety and open questions
Nausea, flushing, facial swelling, spontaneous erections, darkening of existing moles, and case reports of melanoma, priapism, kidney injury and rhabdomyolysis. Regulators have warned against it repeatedly.
Regulatory status
Never approved anywhere. Regulators in the US, UK, Australia and EU have issued warnings against its use. Remains in FDA compounding Category 2.
Status was accurate when this page was last reviewed on October 26, 2026. Regulations change; check with the relevant authority before relying on it.
Melanotan II: common questions
Is melanotan II safe for tanning?
It has never been shown to be safe for that or any purpose, and it is not approved anywhere. Dermatologists have documented mole changes and melanoma reports in users.
Is Melanotan II approved for human use?
Never approved anywhere. Regulators in the US, UK, Australia and EU have issued warnings against its use. Remains in FDA compounding Category 2.
References
- Dorr RT, Lines R, Levine N, et al. (1996). Evaluation of melanotan-II, a superpotent cyclic melanotropic peptide in a pilot phase-I clinical study. Life Sciences.
- Wessells H, Fuciarelli K, Hansen J, et al. (1998). Synthetic melanotropic peptide initiates erections in men with psychogenic erectile dysfunction: double-blind, placebo controlled crossover study. Journal of Urology.
- Habbema L, Halk AB, Neumann M, Bergman W. (2017). Risks of unregulated use of alpha-melanocyte-stimulating hormone analogues: a review. International Journal of Dermatology.
Links open a PubMed search for the exact title, or the original source where one is given.