PT-141 vs Melanotan 2: Structure, Approval and Risks
PT-141 (bremelanotide) vs Melanotan II at a glance
| Fact | PT-141 (bremelanotide) | Melanotan II |
|---|---|---|
| Also known as | Bremelanotide, Vyleesi | Melanotan II, MT-II |
| What it is | Melanocortin receptor agonist (approved medicine in the US) | Synthetic alpha-MSH analogue (unapproved tanning peptide) |
| Evidence level | Approved drug (in at least one market) | Early human trials |
| Approved products | Vyleesi (US, 2019) | None |
| United States | Prescription medicine approved as Vyleesi in June 2019 [2]. | Not FDA-approved; the nomination of melanotan II for pharmacy (503A) compounding was withdrawn after FDA flagged potential safety risks, and FDA plans to consult its compounding advisory committee on it before the end of February 2027 [11][9][21]. |
| United Kingdom | No UK-licensed medicine containing bremelanotide appears in the MHRA products database [12]. | No UK-licensed medicine containing melanotan II appears in the MHRA products database [19]. |
| European Union | No medicine containing bremelanotide is authorized in the EU, according to EMA's central and Article 57 product data [13][14]. | No medicine containing melanotan II is authorized in the EU, according to EMA's central and Article 57 product data [13][14]. |
| Canada | No product containing bremelanotide appears in Health Canada's Drug Product Database [15]. | No product containing melanotan II appears in Health Canada's Drug Product Database [15]. |
| Australia | Bremelanotide is not named in Australia's Poisons Standard (October 2026) [16]. | Schedule 4 (prescription-only) in Australia's Poisons Standard [16]. |
| Sport (WADA) | Not named on the 2026 Prohibited List [17]. | Not named on the 2026 Prohibited List; its section S0 bans any pharmacological substance with no current approval for human therapeutic use [17]. |
| Vendors we track | 66 vendors | 60 vendors |
| Our lab tests | None yet | None yet |
PT-141 and melanotan II are close chemical relatives with very different histories. PT-141 is bremelanotide, which was developed as an analogue of melanotan II [4] and approved in the US in 2019 as Vyleesi for low sexual desire in premenopausal women [2, 3]. Melanotan II was tested in early human studies for tanning and for erectile dysfunction [4, 5] and never became an approved medicine [11]; today it is known mainly from unregulated tanning use and the case reports of harm that followed [8, 9].
What each one is
Both are synthetic, ring-shaped peptides of seven amino acids [1, 5] and analogues of alpha-melanocyte-stimulating hormone (alpha-MSH) [3, 5]. The difference is at one end of the molecule. Vyleesi’s label describes bremelanotide as Ac-Nle-cyclo-(Asp-His-D-Phe-Arg-Trp-Lys-OH), a cyclic heptapeptide with a free acid at the end [1]. Melanotan II has the same sequence but ends in an amide (-NH2) [5].
Both act on several melanocortin receptors rather than one [1, 8]. According to its label, bremelanotide is most potent at the MC1 receptor, followed by MC4R, and binding at MC1R, which is expressed on pigment cells, leads to increased pigmentation [1]. A 2019 journal review of its first approval describes its high affinity for MC4R, a receptor thought to be important for sexual function [3].
How the evidence compares
Bremelanotide went through full drug development. Two identical phase 3 trials (RECONNECT) randomized 1,267 premenopausal women with hypoactive sexual desire disorder; women on bremelanotide reported statistically significant increases in sexual desire and reductions in related distress compared with placebo, and most adverse events were mild or moderate [6]. A 2024 reanalysis argued that the benefits were statistically modest and that several outcome measures had little evidence of validity for this condition [7].
Melanotan II was also tested clinically for erectile dysfunction [4], and its early human evidence includes a 1996 pilot phase 1 study in three men [5]. It produced skin darkening, mild nausea, drowsiness and fatigue, and spontaneous erections [5]. Later case reports after unregulated use include a kidney (renal) infarction [8]. A dermatology review of unregulated melanotan I and II use describes changes in existing moles, new atypical moles and four melanomas arising from existing moles, although conclusive evidence of a causal link is lacking [10]. FDA cites published case reports of melanoma, posterior reversible encephalopathy syndrome, sympathomimetic toxidrome and priapism [9].
Even the approved drug carries warnings. Vyleesi’s label lists transient increases in blood pressure with decreases in heart rate, nausea, and focal hyperpigmentation of the face, gums and breasts, which was reported by 1% of patients in the phase 3 trials and by none on placebo, and by 38% in another study that used it daily for 8 days [1].
Regulation and sport
Bremelanotide is approved by FDA only as the prescription product Vyleesi [2]. Melanotan II has never been approved by FDA [11], which lists it among compounding substances that may present significant safety risks [9]; the table above covers the other markets and sport.
Quality risks when buying
Vyleesi is a prescription autoinjector [1]; vials sold online as “PT-141” are not that product. Unregulated melanotan products have prompted safety warnings from several national health organizations [10]. Because the two molecules differ only at one end [1, 5], a purity figure alone can’t tell them apart: an independent report should confirm the identity by molecular mass and match the batch you receive.
Our guides explain how to read a peptide COA, how to check a peptide vendor and what “research use only” means. For the other melanotan, see melanotan 1 vs melanotan 2.
More on each
The PT-141 overview and the melanotan II overview list each compound’s full sources. We track current listings on the PT-141 price page and the melanotan II price page.
Frequently asked questions
What is the difference between PT-141 and melanotan 2?
PT-141 is bremelanotide, a close analogue of melanotan II. Both are ring-shaped seven-amino-acid peptides with the same sequence; bremelanotide ends in a free acid where melanotan II ends in an amide. Bremelanotide became an approved prescription drug; melanotan II never did.
Is PT-141 approved?
Bremelanotide is approved in the US as Vyleesi, a prescription autoinjector for premenopausal women with acquired, generalized hypoactive sexual desire disorder. Vials sold online as "PT-141" are not Vyleesi.
Does PT-141 cause tanning like melanotan 2?
It can darken patches of skin. Vyleesi's label warns of focal hyperpigmentation, including of the face, gums and breasts. It was reported by 1% of patients in the phase 3 trials and none on placebo, but by 38% of patients in another study that used it daily for 8 days; it was more likely in people with dark skin and did not always fade after stopping. In melanotan II's first human study, two of the three men had increased pigmentation of the face, upper body and buttocks.
How much safety data is there for PT-141 and melanotan 2?
Far more for bremelanotide, which was tested in two phase 3 trials with 1,267 women before approval. Melanotan II's early human research included a pilot study in three men; since then, case reports have linked unregulated use to melanoma, kidney infarction and other serious events, without proving cause.