The Short Answer
PT-141 is the research code name for bremelanotide, a synthetic peptide that activates melanocortin receptors in the brain. FDA approved it on June 21, 2019 as Vyleesi, an autoinjector for premenopausal women with acquired, generalized hypoactive sexual desire disorder (HSDD): low sexual desire that causes distress and isn't explained by another condition, a relationship problem, or a medication.
That makes PT-141 unusual among the peptides people search for: it has a label, two Phase 3 trials, and known side-effect rates. It also has limits the marketing leaves out. Vyleesi is not approved for men, for postmenopausal women, or to enhance sexual performance, and the "PT-141" sold by research-chemical sites is not the approved product.
This guide is educational and doesn't give dosing instructions. Vyleesi's dose is on its label and set by a prescriber.
PT-141 at a Glance
| Generic name | Bremelanotide |
| Research name | PT-141 |
| Brand | Vyleesi (single-dose autoinjector) |
| Class | Melanocortin receptor agonist |
| FDA approval | June 21, 2019 (NDA 210557) |
| Approved for | Acquired, generalized HSDD in premenopausal women |
| Not approved for | Men; postmenopausal women; enhancing sexual performance |
| Contraindicated | Uncontrolled hypertension or known cardiovascular disease |
How PT-141 Works
Most erectile-dysfunction drugs (sildenafil, tadalafil) work on blood vessels. Bremelanotide works on the brain. It's derived from alpha-melanocyte-stimulating hormone and activates melanocortin receptors, particularly MC4R, in pathways involved in sexual desire. That's why it's studied for desire rather than for erection or arousal mechanics, and why its side effects include things like flushing and blood-pressure changes rather than vision changes.
The same receptor family controls skin pigmentation, which explains one of the label's warnings below. Bremelanotide is chemically related to Melanotan II, the unapproved tanning peptide; both came out of the same research program.
What the Trials Showed
The approval rested on two identical Phase 3 trials, RECONNECT studies 301 and 302, published in Obstetrics & Gynecology in 2019. A total of 1,267 premenopausal women with HSDD were randomized to bremelanotide or placebo, used as needed, for 24 weeks. Women on bremelanotide had statistically significant increases in sexual desire scores and decreases in desire-related distress compared with placebo. The effect sizes were modest. Nausea, flushing and headache occurred in 10% or more of participants in both trials.
The label notes that the duration of effect after each dose is unknown and that the optimal timing window has not been fully characterized.
Side Effects and Warnings on the Vyleesi Label
- Nausea: reported by 40% of patients in the trials. Thirteen percent needed anti-nausea medication and 8% stopped treatment because of it. The label says nausea improved for most patients with the second dose.
- Transient blood-pressure increase and heart-rate decrease after each dose, usually resolving within 12 hours. In studies the peak increases were about 6 mmHg systolic and 3 mmHg diastolic. This is why uncontrolled hypertension and known cardiovascular disease are contraindications, and why the label advises against use in people at high cardiovascular risk.
- Focal hyperpigmentation: darkening of skin patches, including on the face, gums and breasts, reported by 1% of patients. Risk is higher with darker skin and with more frequent dosing, and it didn't always resolve.
- Most common reactions (over 4%): nausea, flushing, injection-site reactions, headache and vomiting.
The label also sets limits on how often Vyleesi may be used in a day and in a month. Those limits exist because of the blood-pressure and pigmentation effects, and they're the prescriber's to explain.
Research-Grade "PT-141" vs Vyleesi
The vials sold online as PT-141 are not Vyleesi. The differences matter:
| Vyleesi | Online "PT-141" | |
|---|---|---|
| FDA review | Approved; manufacturing inspected | None |
| What's in it | Fixed dose of bremelanotide in an autoinjector | Lyophilized powder of unverified identity and purity |
| Who can get it | Prescription from a licensed clinician | Sold as "research use only" |
| Legal for human use | Yes, as prescribed | No |
FDA's 2026 warning letters make clear that a "research use only" label doesn't protect sellers who market peptides for human use. If you're evaluating a product anyway, our guide to reading a certificate of analysis explains what independent testing can show, and the shelf-life tool covers storage after reconstitution. Neither makes an unapproved vial equivalent to the drug.
What About Men?
Bremelanotide was studied in men with erectile dysfunction before the HSDD program, and some clinics prescribe it off-label. Vyleesi's label states it is not indicated for men, and the Phase 3 evidence base is in premenopausal women. Off-label use is a clinician's decision with a patient, made with the blood-pressure warnings in view. It isn't something to self-source.
When to See a Clinician
Low sexual desire has many causes: medications (antidepressants are a common one), hormonal changes, depression, relationship factors, and medical conditions. The Vyleesi indication specifically excludes desire problems explained by those causes, which means a proper evaluation comes first. A licensed clinician can rule those out, check blood pressure, review the contraindications, and decide whether Vyleesi or another option fits. The compound profile and peptide glossary entry have quick-reference facts.
