What it is
PT-141 (bremelanotide) is a synthetic peptide that activates melanocortin receptors in the brain. Unlike drugs that work on blood flow, it targets the central nervous-system circuits thought to govern sexual desire and arousal.
It is FDA-approved as Vyleesi, cleared in June 2019 for acquired, generalized hypoactive sexual desire disorder (HSDD) in premenopausal women. Vyleesi is a prescription, single-use subcutaneous autoinjector taken on an as-needed basis, at least 45 minutes before anticipated sexual activity.
The 'research peptide' PT-141 sold on grey-market sites is the same molecule but is NOT the approved product. It is unregulated lyophilized powder marketed for laboratory use only, with no FDA oversight of its purity, dose, or sterility.
How it works
Bremelanotide is an analog of alpha-melanocyte-stimulating hormone (alpha-MSH) and acts as an agonist at melanocortin receptors, particularly MC4R, in the central nervous system. This is fundamentally different from PDE5 inhibitors like Viagra, which increase genital blood flow. PT-141 instead engages brain pathways associated with sexual motivation.
Because its action is central rather than vascular, the effect is framed as influencing desire and arousal signaling in the brain rather than producing a mechanical erection. The FDA notes the exact mechanism remains incompletely understood, but binding to central melanocortin receptors is believed to underlie its effect on sexual function.
What people research it for
Increased sexual desire in women with HSDD
Human studiesIn pivotal trials, about 25% of Vyleesi users had a meaningful rise in their sexual-desire score versus about 17% on placebo.
Reduced distress about low desire
Human studiesBremelanotide significantly lowered the distress women reported from low sexual desire compared with placebo.
Central, on-demand mechanism
Human studiesWorks on brain desire pathways and is taken as-needed before activity, rather than daily or based on blood flow.
Off-label interest for arousal in men
Early human dataIts central mechanism has drawn off-label attention for male sexual function, but it is not approved for men and evidence is limited.
What the research actually shows
The strongest evidence comes from the two identical Phase 3 RECONNECT trials: randomized, double-blind, placebo-controlled studies in over 1,200 premenopausal women with HSDD, using 1.75 mg subcutaneously as needed over 24 weeks with an optional open-label extension. These trials supported the 2019 FDA approval.
Earlier work explored bremelanotide (as an intranasal formulation) for erectile dysfunction in men, but that program did not lead to approval, partly due to blood-pressure effects. Male use today is off-label and not backed by pivotal approval trials.
Honest limits: the approved benefit is modest and specific to premenopausal women with HSDD. Claims about broad libido enhancement, use in men, or use in postmenopausal women go beyond what the controlled evidence supports.
Research handling & storage
The approved product, Vyleesi, is a pre-filled single-use subcutaneous autoinjector delivering a fixed 1.75 mg dose into the abdomen or thigh; no mixing is required and it is manufactured under regulated conditions.
Grey-market research PT-141 is typically sold as lyophilized (freeze-dried) powder that a buyer would reconstitute with bacteriostatic water. Powder is generally stored cold and protected from light, and reconstituted solution kept refrigerated. Because this version is unapproved, its actual dose and sterility are unverified. This is described as research context only, not a usage instruction.
Safety & cautions
The most common side effects in trials were nausea (reported by roughly 40% of patients, sometimes requiring anti-nausea medication), flushing (about 20%), injection-site reactions, headache, and vomiting. Vyleesi also causes a transient rise in blood pressure that peaks a few hours after dosing and usually returns to baseline within about 12 hours; it is not recommended for people with uncontrolled high blood pressure or cardiovascular disease. Focal hyperpigmentation (darkening of skin/gums, seen in about 1% of users) may not fully resolve after stopping.
The grey-market 'research' version carries additional, poorly-quantified risks: unknown purity and dosing, non-sterile reconstitution, and no medical oversight. Only the FDA-approved Vyleesi has established safety monitoring. Anyone considering it should consult a licensed clinician rather than self-source an unapproved product.
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Frequently asked questions
Is PT-141 FDA approved?
Yes, as the branded drug Vyleesi (bremelanotide injection), approved in 2019 for acquired, generalized hypoactive sexual desire disorder in premenopausal women. The grey-market 'research' PT-141 powder is the same molecule but is not FDA-approved or regulated.
How is PT-141 different from Viagra?
Viagra (a PDE5 inhibitor) works on blood flow to produce erections. PT-141 acts centrally on melanocortin receptors in the brain, targeting sexual desire and arousal signaling rather than the vascular system.
Does it work for men?
It is only approved for premenopausal women. Off-label use in men exists, but there are no pivotal approval trials supporting it, and an earlier ED program did not gain approval.
What are the most common side effects?
Nausea (the most frequent), flushing, injection-site reactions, headache, and vomiting, plus a transient rise in blood pressure and rare skin/gum darkening.
Is the research powder the same as Vyleesi?
It is the same peptide chemically, but not the same product. Vyleesi is a regulated, pre-dosed autoinjector; grey-market powder has no verified dose, purity, or sterility.
Sources
- FDA news release — approval of Vyleesi (bremelanotide) for HSDD
- FDA prescribing information / label — Vyleesi (bremelanotide injection)
- RECONNECT Phase 3 trials — Bremelanotide for HSDD (PubMed)
- Bremelanotide — LiverTox / NCBI Bookshelf (NIH)
Last reviewed 2026-07-07. This guide is educational and research-focused — not medical advice. PT-141 products referenced on PeptidePub are sold by third parties as materials for laboratory research use only, not for human or animal consumption.
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