PT-141 (bremelanotide) is a melanocortin peptide that the FDA approved in 2019 as Vyleesi, an as-needed injection for low sexual desire in premenopausal women.[2][1] In two phase 3 trials, it improved desire and reduced distress more than placebo, though the gains were modest.[3] Nausea affected 40% of users.[1] It is not approved for men.[1] For dose math on vials, see our peptide calculator.
What is PT-141?
PT-141 is a cyclic 7-amino-acid peptide developed by Palatin Technologies from Melanotan II, a tanning peptide created at the University of Arizona.[16] It activates several melanocortin receptors; at the approved dose, MC1R and MC4R matter most. MC4R is found in the brain, and MC1R on pigment cells, which explains the skin darkening some users get.[1] Palatin sold Vyleesi to Cosette Pharmaceuticals in 2023.[12]
PT-141 results
- RECONNECT phase 3 (1,267 women): desire scores improved by 0.30 to 0.42 points more than placebo, and distress about low desire fell.[3]
- 52-week extension: benefits held, with no new safety signals.[4]
How the RECONNECT trials were run
The two identical trials randomly assigned women to Vyleesi 1.75 mg or placebo for 24 weeks. Participants averaged 39 years old (range 19 to 56), had been in a monogamous relationship for about 12 years, and had lived with low desire for about 4 years. They injected as needed, and most used it two to three times a month; the median was 10 injections over 24 weeks.[1]
Desire was scored from 1.2 to 6 on the Female Sexual Function Index. Average scores rose by 0.5 to 0.6 points on Vyleesi versus 0.2 on placebo. Distress about low desire, scored from 0 to 4, fell by 0.7 versus 0.4.[1] Two caveats from the label: the number of satisfying sexual events did not differ from placebo, and more women stopped early on Vyleesi (40% vs 13% in one trial and 39% vs 25% in the other).[1]
- Phase 2b: women on effective doses had more satisfying sexual events per month (+0.7 vs +0.2).[5]
How PT-141 works vs Viagra
Viagra (sildenafil) increases blood flow to the penis. PT-141 instead acts on melanocortin receptors in the brain, which are involved in sexual desire and arousal.[20] The Vyleesi label says its exact mechanism in low sexual desire is unknown.[1] Because it works differently, early studies tested it in men who did not respond to Viagra.[8]
PT-141 for men
The label says Vyleesi is not for men.[1] Early Palatin studies found:
-
Nasal PT-141: doses above 7 mg produced erections versus placebo in healthy men and in men with mild to moderate erectile dysfunction who respond to Viagra.[7]
-
Injected PT-141: produced erections in men who had not responded to Viagra.[8]
-
With sildenafil: a low nasal dose plus 25 mg sildenafil gave a stronger response than sildenafil alone in 19 men.[9]
-
Larger trial: in 342 men who had not responded to sildenafil, nasal bremelanotide reported benefit over placebo, but the journal has since issued an expression of concern about the paper.[21]
These doses differ from the 1.75 mg Vyleesi dose. A 2026 commentary examined whether bremelanotide should be considered for sexual desire and arousal problems in men.[19]
PT-141 dosage
| Vyleesi label | |
|---|---|
| Dose | 1.75 mg injected under the skin of the abdomen or thigh[1] |
| Timing | At least 45 minutes before anticipated sexual activity[1] |
| Limits | No more than 1 dose in 24 hours; no more than 8 doses per month[1] |
| When to stop | After 8 weeks if there is no improvement[1] |
PT-141 side effects
From the Vyleesi label:[1]
| Side effect | Vyleesi | Placebo |
|---|---|---|
| Nausea | 40.0% | 1.3% |
| Flushing | 20.3% | 0.3% |
| Injection-site reactions | 13.2% | 8.4% |
| Headache | 11.3% | 1.9% |
| Vomiting | 4.8% | 0.2% |
- Blood pressure: rises by up to 6/3 mmHg for several hours after each dose. Not for people with uncontrolled high blood pressure or heart disease.[1]
- Skin darkening: 1% at the approved dose, but 38% when dosed daily for 8 days; it may not fade.[1]
- Drug interactions: it lowers levels of oral naltrexone and can slow absorption of other pills.[1][6]
- Stopping: 18% stopped due to side effects versus 2% on placebo.[1]
More on nausea. It usually started within an hour of the injection and lasted about two hours. It was most common after the first dose (21%) and fell to about 3% with later doses. In trials, 13% of women took an anti-nausea medicine and 8% quit because of nausea. Taking ondansetron 30 minutes beforehand did not prevent it in a 228-woman study.[1]
Other medicines and alcohol. Because Vyleesi can slow stomach emptying, the label advises avoiding it when taking pills that must reach a steady level to work, such as antibiotics, and notes it delayed the effect of the pain reliever indomethacin.[1] In a study of a higher nasal dose with alcohol, alcohol did not change blood levels of bremelanotide, but headache was more common than with bremelanotide alone.[1]
Who should not use PT-141
- People with uncontrolled high blood pressure or known heart disease.[1]
- Postmenopausal women and men, for whom it is not approved.[1]
- People taking oral naltrexone for alcohol or opioid dependence.[1]
- People with darker skin should know they are more likely to develop skin darkening.[1]
- Anyone who is or may be pregnant. Animal studies suggest possible harm to a fetus, so the label advises effective contraception and stopping if pregnancy is suspected.[1]
- People with severe kidney or liver impairment should use it with caution, because nausea and vomiting may be more frequent or severe.[1]
Before starting, it can help to ask your clinician: Is my blood pressure well controlled? Do any of my daily pills interact with it? What should I do if nausea is bad after the first dose? The label says to stop after 8 weeks if there is no improvement.[1]
How long does PT-141 last?
Blood levels peak about an hour after injection, and the half-life is about 2.7 hours.[1] The blood pressure rise usually resolves within 12 hours,[1] and some reviewers report effects lasting into the next day.[18]
PT-141 nasal spray
Palatin’s early research in men used a nasal spray at doses above 7 mg.[7][9] The only FDA-approved form is the Vyleesi injection; nasal sprays sold online are not FDA-approved products.[1]
Vyleesi vs Addyi
| Vyleesi (bremelanotide) | Addyi (flibanserin) | |
|---|---|---|
| Form | As-needed injection[1] | Daily pill at bedtime[15] |
| Approved for | Premenopausal women[1] | Women under 65[15] |
| Boxed warning | None[1] | Low blood pressure and fainting with alcohol, moderate or strong CYP3A4 inhibitors, or liver impairment[15] |
| Most common side effects | Nausea, flushing[1] | Dizziness, sleepiness, nausea[15] |
PT-141 for weight loss
In a small trial in women with obesity, PT-141 taken three times daily reduced body weight 1.3 kg more than placebo over 16 days; a second short crossover trial found a similar effect.[10] In a 2025 company-reported 8-week trial, PT-141 plus tirzepatide produced 4.4% weight loss versus 1.6% on placebo, and 40% lost at least 5% versus 27% on tirzepatide alone; this has not been peer reviewed.[11]
Is PT-141 legal?
- US: FDA-approved as Vyleesi by prescription.[1]
- Sports: bremelanotide is not named on WADA’s 2026 list and is FDA-approved; athletes should still check with their anti-doping organization.[17]
See also Melanotan II, the unapproved tanning peptide PT-141 came from.
