Melanotan II
A synthetic melanocortin agonist sold online as an injectable "tanning" peptide. It is not approved as a medicine anywhere, and its purity and safety in unregulated products are uncertain.
Quick take
- What it is: a synthetic analogue of α-MSH that activates several melanocortin receptors, darkening skin.
- What people use it for: mostly cosmetic tanning; users also report appetite suppression and increased libido.
- What we actually know: it does stimulate pigmentation, but human safety data are thin and it is sold only as an unregulated product.
- Status: not approved as a medicine anywhere; regulators have warned against unlicensed injectable tanning products.
What it is
Melanotan II is a synthetic analogue of α-melanocyte-stimulating hormone (α-MSH). It is a broader, less selective melanocortin agonist than Melanotan I, and it is sold online almost exclusively as an injectable “tanning” peptide rather than as an approved medicine.1
It is important not to confuse it with Melanotan I (afamelanotide), which has an approved medical implant. Melanotan II has no approved formulation anywhere.
How it works
Melanotan II activates several melanocortin receptors, including MC1R (which drives skin pigmentation) and MC4R (involved in appetite and sexual function). MC1R activation increases melanin production, while its action at other receptors explains reported effects on appetite and libido.1,2 Its activity at MC4R is closely related to that of PT-141, which was developed from this peptide family.
What the evidence shows
Animal studies
Melanocortin agonists reliably stimulate pigmentation in animal models, and MC4R activity has been studied in relation to appetite and sexual behaviour.2 This established the broad mechanism.
Human studies
Published, controlled human trials of Melanotan II for tanning are very limited, and there is no approved indication. Most information about its effects in people comes from small studies, case reports and anecdotal use rather than rigorous trials.3 Case reports have described complications including changes in moles and, in men, prolonged erections.
Dosages reported in the literature
Informational only. The figures below describe doses reported in unregulated use. They are not a recommendation or a prescription. There is no approved dosing for Melanotan II, and any use should be discussed with a qualified healthcare professional.
| Setting | Route | Reported range |
|---|---|---|
| Unregulated tanning use | Subcutaneous injection | Variable microgram-range protocols; not standardised |
| Approved medical use | — | None — no approved formulation |
Because there are no dose-finding trials and no approved product, no range here should be read as established as safe or effective.
Safety & side effects
Commonly reported effects include nausea, facial flushing, and darkening of moles and freckles. Because of its action at MC4R, spontaneous prolonged erections (priapism) have been reported in men.3 Changes in pigmented lesions are a particular monitoring concern, and some case reports describe new or changing moles.3
A further, central concern is that Melanotan II is sold only as an unregulated product. Purity, dose accuracy and sterility are not assured, and regulators have warned against unlicensed injectable tanning agents.4
Legal & regulatory status
Melanotan II is not approved by the FDA or other major regulators for any use. It is not a licensed medicine, and selling it for human injection is generally unlawful in many jurisdictions; several agencies have issued warnings about unlicensed tanning products.4 Rules differ by country and change over time.
References
- Hadley ME, Dorr RT. Melanocortin peptide therapeutics: historical milestones, clinical studies and commercialization. Peptides. 2006;27(4):921-930. [PMID 16412534, doi:10.1016/j.peptides.2005.01.029]
- Mun Y, Kim W, Shin D. Melanocortin 1 Receptor (MC1R): Pharmacological and Therapeutic Aspects. Int J Mol Sci. 2023;24(15):12152. [PMID 37569558, doi:10.3390/ijms241512152]
- Dorr RT, Lines R, Levine N, Brooks C, Xiang L, Hruby VJ, Hadley ME. Evaluation of melanotan-II, a superpotent cyclic melanotropic peptide in a pilot phase-I clinical study. Life Sci. 1996;58(20):1777-1784. (DOI 10.1016/0024-3205(96)00160-9, PMID 8637402). AND Paurobally D, Jason F, Dezfoulian B, Nikkels AF. Melanotan-associated melanoma. Br J Dermatol. 2011;164(6):1403-1405. (DOI 10.1111/j.1365-2133.2011.10273.x, PMID 21564053). [PMID 8637402, PMID 21564053, doi:10.1016/0024-3205(96)00160-9, doi:10.1111/j.1365-2133.2011.10273.x]
- UK Medicines and Healthcare products Regulatory Agency (MHRA) warning that Melanotan tanning injections are an unlicensed medicine, unsafe and illegal to sell/supply in the UK (2008/2009), as reported by Cancer Research UK, ‘Tanning, fake tan and Melanotan’. Corroborated by U.S. FDA Warning Letter to Melanocorp Inc. regarding unapproved marketing of Melanotan II as an injectable tanning product (2007). [cancerresearchuk.org]