Melanotan 1 vs Melanotan 2: Approval, Evidence and Risks

By Editorial team. Updated Oct 15, 2026. Awaiting expert review

Melanotan I and melanotan II are both synthetic analogues of alpha-melanocyte-stimulating hormone (alpha-MSH), and both were first tested in small human studies for skin tanning [2, 3]. After that, their paths split. Melanotan I is the same molecule as afamelanotide [2, 14], the active ingredient of an approved prescription implant for a rare light-sensitivity disorder [4, 7, 8]. Melanotan II never became an approved medicine [13], and much of what is known about it comes from case reports of harm after unregulated use [9, 11].

What each one is

Melanotan I (MT-1) is [Nle4-D-Phe7]-alpha-MSH: a linear peptide that keeps the 13-amino-acid length of alpha-MSH with two amino acids changed [2, 1]. Under the name afamelanotide it is the active ingredient of Scenesse, and it acts on the melanocortin-1 receptor (MC1R) [4].

Melanotan II (MT-2) is shorter and ring-shaped: a cyclic, lactam-bridged peptide of seven amino acids based on part of the alpha-MSH sequence [3, 1]. It is a non-selective melanocortin receptor agonist, and its reported effects in humans include sexual arousal as well as darker skin [5]. It was tested clinically for erectile dysfunction as well as tanning [1], and the approved drug bremelanotide was developed from it (see PT-141 vs melanotan 2) [1].

How the evidence compares

Melanotan I has the stronger human record, largely because it was developed into a medicine. An early study in three men found significant tanning with minimal side effects, mainly occasional stomach upset and facial flushing [2]. As afamelanotide, it was then tested in two randomized, placebo-controlled trials in people with erythropoietic protoporphyria, a painful light-sensitivity disorder: patients given the implant could spend longer in direct sunlight without pain, and adverse events were mostly mild [6].

Melanotan II’s early human research included a 1996 pilot study in three men [3]. It produced skin darkening, along with nausea, fatigue, drowsiness and spontaneous erections [3]. Since then, unregulated use has produced case reports of harm, including a melanoma in a young woman who used it alongside sunbeds [10] and a kidney (renal) infarction [5]. FDA cites published case reports of melanoma, posterior reversible encephalopathy syndrome, sympathomimetic toxidrome and priapism [11].

The unregulated versions of both carry similar warnings. A dermatology review links unregulated use of melanotan I and II with changes in existing moles and new atypical moles, and counts four case reports of melanoma arising from existing moles during or shortly after use [9]. It notes that conclusive evidence of a causal link is lacking [9].

Regulation and sport

Afamelanotide has been authorized in the EU as Scenesse since December 2014 and approved by FDA since October 2019 [7, 8]. Melanotan II has never been approved by FDA [13], which lists it among compounding substances that may present significant safety risks [11]; the table above shows each market and sport.

Quality risks when buying

Scenesse is a biodegradable, controlled-release implant [4]. Products sold online as melanotan I or II are unregulated, and the UK medicines regulator has warned about their potential impurity and about the risk of blood-borne viruses from shared needles [12]. The dermatology review above also raises questions about how such products are prepared [9]. Because the two compounds are different molecules sold under similar names [1], an independent lab report should confirm which one a vial contains by its molecular mass, not just its purity.

Our guides explain how to read a peptide COA, how to check a peptide vendor and what “research use only” means.

More on each

See the melanotan I overview and the melanotan II overview for each compound’s full sources. We track current listings on the melanotan I price page and the melanotan II price page.