PT-141 (Bremelanotide / Vyleesi)

PT-141 (bremelanotide) is unusual for this corner of the world: it’s an actual FDA-approved drug, sold under the name Vyleesi. But that approval covers only one narrow situation, and most of the reasons people reach for PT-141 fall well outside it. The science behind the approved use is solid and carefully done. The science behind everything else just isn’t there.

What it is

Bremelanotide is a synthetic peptide (a small, lab-made protein-like molecule) that switches on melanocortin receptors in the brain — mainly one called MC4R, with some activity at another called MC1R. This is different from how sildenafil (Viagra) works. Viagra acts on blood flow; PT-141 acts on the brain pathways tied to sexual desire and arousal. Exactly how it shifts desire isn’t fully understood. It’s taken as a subcutaneous injection (a shot under the skin) about 45 minutes before sex.

The claims

Marketing and clinic websites pitch PT-141 as a libido and arousal booster for both women and men, and as a fix for erectile dysfunction. Online sellers offer unapproved “research” vials meant for do-it-yourself injection. The approved use is far narrower than any of that: it’s for premenopausal women with acquired, generalized hypoactive sexual desire disorder (HSDD) — meaning low sexual desire that started at some point (rather than lifelong) and shows up across situations.

What the evidence actually shows

This is the rare case where real, large human trials exist. The Phase 3 RECONNECT program (Studies 301 and 302, about 1,200 women in the main analysis) ran two identical 24-week trials that were randomized, double-blind, and placebo-controlled — the gold-standard setup where neither patients nor doctors know who’s getting the real drug versus a dummy injection. Both trials hit their main goals: women on PT-141 saw statistically meaningful gains in a desire score and drops in desire-related distress compared with placebo.

The catch is that the effect is small. On the FSFI desire score (a questionnaire that runs from 1.2 to 6.0), the average improvement over placebo was about 0.35 points. Looked at another way the FDA used — counting how many women had a meaningful response — about 25% of treated women cleared that bar versus about 17% on placebo. And here’s a notable point: the number of satisfying sexual events did not improve in a statistically meaningful way in the planned analysis. So the honest read for the approved use is “real, but modest” — a true drug effect that helps a minority of women more than placebo does.

That strength doesn’t carry over to other uses, where the evidence ranges from thin to nonexistent. An older nasal-spray version was tested in men with erectile dysfunction (Diamond et al.) and did produce erections, but that line of development was dropped over blood-pressure concerns. There’s no finished Phase 3 program and no approval for men. Using it for general libido, male ED, or in postmenopausal women is off-label (outside the approved use) and largely untested in modern controlled trials.

The grade here is about the approved use only, where the human evidence really is strong. Read it narrowly: strong evidence for a small benefit in one specific group — not evidence that PT-141 broadly “works” for desire or erections in everyone.

Legal and regulatory status

In the United States, Vyleesi (bremelanotide) has been FDA-approved since June 2019 for acquired, generalized HSDD in premenopausal women. Palatin Technologies sold the worldwide rights to Cosette Pharmaceuticals in December 2023, and the product is still on the market. The gray-market “research” peptide sold for self-injection is not the approved product and isn’t quality-controlled, so you can’t be sure what’s actually in it.

For athletes: bremelanotide is a melanocortin agonist, and it isn’t specifically named on the 2026 WADA Prohibited List (the 2026 updates to the peptide-hormone section S2 added other substances, not melanocortins). Don’t confuse it with the unapproved tanning peptides melanotan I/II — those are different compounds. Anti-doping rules can change and depend on the situation, so competitors should check the current status of any product through Global DRO before using it.

Safety

Side effects are common and well-documented on the label. Nausea hit about 40% of treated patients (versus roughly 1% on placebo), often with the very first dose; about 13% needed anti-nausea medication and about 8% quit because of it. Flushing, headache, and reactions at the injection site were also frequent.

PT-141 briefly raises blood pressure and lowers heart rate after each dose (these effects usually fade within about 12 hours). Because of that, it’s not for people with uncontrolled high blood pressure or known heart disease, and it isn’t recommended for those at high heart-risk. About 1% of patients on the approved monthly schedule developed patches of darkened skin (including the face, gums, and breasts); in some, it wasn’t confirmed whether the darkening went away after stopping, and the risk is higher with daily dosing and in people with darker skin. Rare liver injury has been reported (one well-documented case in the published research). Safety beyond the trial periods isn’t well understood, and self-injecting an unapproved product piles on more risk that nobody has measured.

Bottom line

PT-141 is a legitimate, FDA-approved drug with a small but genuinely proven benefit for one specific condition: low sexual desire in premenopausal women. The bigger claims — for men, for general libido, for erectile dysfunction — rest on little or no controlled human evidence, and the side-effect and heart-related profile isn’t trivial. Strong evidence for a narrow, modest effect is not the same as a reason to use it broadly. This is not medical advice.

Evidence grade: 10/10 · Established. (for the approved premenopausal HSDD indication only; off-label uses are unstudied).

Sources

• FDA approves new treatment for hypoactive sexual desire disorder in premenopausal women (FDA news release, 2019)
• VYLEESI (bremelanotide injection) Prescribing Information, DailyMed
• Simon JA et al. Bremelanotide for the Treatment of Hypoactive Sexual Desire Disorder: Two Randomized Phase 3 Trials (Obstet Gynecol, 2019), PubMed 31599840
• Bremelanotide — LiverTox, NCBI Bookshelf (NBK573221)
• Diamond LE et al. Intranasal PT-141 in healthy males and patients with erectile dysfunction, PubMed 14963471
• Palatin Completes Sale of Vyleesi to Cosette Pharmaceuticals (December 2023)
• WADA’s 2026 Prohibited List is now in force, World Anti-Doping Agency
• Athlete Advisory: What’s New on the 2026 WADA Prohibited List? (USADA)