PT-141 (bremelanotide, Vyleesi)
PT-141 (Bremelanotide): What The Studies Actually Say
A real FDA-approved drug for one narrow use: low sexual desire in women who have not gone through menopause. In the big trials it beat placebo by a small margin, 4 in 10 women got nausea, and nearly 1 in 5 quit. It is not approved for men. Here is what the studies actually found.
Updated 22 September 2026
Before you read this
This page explains what published studies found. That is all it is. It is not medical advice, and it is not instructions for using anything. Nothing here is meant to find, treat, cure or stop any illness. The compounds discussed on this site, retatrutide included, are not approved by the FDA for use in people. Research compounds are sold for laboratory use only — not for use in humans or animals. A study tells you what happened to the people in it. It does not tell you what would happen to you. What you do with what you read here is your responsibility, so talk to a doctor first. This page is published by Ascend Vials, which sells research compounds.
Read the full guide
Confirm you have read the notice above and enter an email address. We will send you a link back to this guide, and sometimes an email when we publish a new one. You can unsubscribe any time.
PT-141 gets sold online as a libido shot for anyone. The one approval it has is much narrower than that.
Here is what the actual research found. Every claim has a link. Read them yourself.
The 30-second version
- PT-141 is a real drug called bremelanotide. The FDA approved it in 2019 as Vyleesi — for one use: low sexual desire that causes distress, in women who have not gone through menopause.
- The label says it is not for men, not for women after menopause, and not for boosting sexual performance.
- In two big trials, desire rose about a third of a point more than on placebo, on a scale from 1.2 to 6.0. Satisfying sex did not become more frequent.
- 4 in 10 women got nausea. Nearly 1 in 5 quit because of side effects.
- Every dose briefly raises blood pressure. Some people get dark skin patches that do not always fade.
- Even the FDA label says nobody knows how it works for low desire.
- Nothing sold online has been shown to match what the trials used. No study has checked.
The numbers, from the real studies
The main evidence is two identical trials, called RECONNECT. They had 1,267 women with hypoactive sexual desire disorder: low desire that causes real distress and is not explained by another illness, a relationship problem or a medicine. Their average age was 39. About half got a fake shot. Each used it as needed, not daily, for 24 weeks. Obstetrics & Gynecology, 2019 · FDA label
Both trials beat placebo, and the result was unlikely to be luck. But look at the size. The desire questionnaire runs from 1.2 to 6.0, and the drug added about a third of a point. The math used to plan the trials had assumed a full point. How much low desire bothered women also fell a little more than on placebo — about a third of a point on a 0-to-4 scale. Obstetrics & Gynecology, 2019
What the headline leaves out:
- Satisfying sex did not increase. The trials' key backup measure, satisfying sexual events a month, was no different from placebo.
- Placebo helped too. About 58% of women on the drug said it had helped. So did about 36% on the fake shot.
- Fewer finished on the drug. Of the 856 women who completed the 24 weeks, 363 had been on the drug and 493 on placebo — from groups that started about the same size.
Obstetrics & Gynecology, 2019 · FDA label
An earlier 12-week study of 397 women did find about half a satisfying event more per month than placebo, on the higher doses. In the big trials, that gain did not show up. Women's Health, 2016
An outside look at the same data
The big trials were paid for by the companies selling the drug, Palatin and AMAG. Obstetrics & Gynecology, 2019 In 2021 an independent researcher reanalyzed both, using the data filed with the FDA. The benefit came out about the same. But for about every 6 women who took the drug, 1 more quit over side effects than would have on placebo. And about 73% of the outcomes listed in the trial plans were never reported in the main paper. Journal of Sex Research, 2021 A 2024 follow-up checked 8 of the unpublished outcomes. The effects ranged from nothing to small. Follow-up, 2024
Afterward, 684 women took the drug for up to a year, knowing what it was. Only 272 finished. Scores improved, but with no placebo group and most women gone, nobody can say how much was the drug. Obstetrics & Gynecology, 2019
What it has been tested for
| Biggest study in people | What it found | Approved for it? | |
|---|---|---|---|
| Low desire, women before menopause | 2 trials, 1,267 women, 24 weeks | Desire up about 1/3 point vs placebo | Yes, US, 2019 |
| Erections in men | Small lab studies | Stronger erections than placebo | No. Program withdrawn, 2017 |
| Weight loss | Small company trials, 15 days or less | 1.3 kg more lost than placebo | No |
| Weight loss with tirzepatide | 96 people, 8 weeks, press release | 4.4% lost vs 1.6% on placebo | No |
| Kidney damage in diabetes | 16 people, no placebo, press release | Less protein in urine | No |
| Tanning, or libido in healthy people | No controlled study | — | No |
Read the whole table. The first row stands on two big trials. Every row under it rests on small studies, press releases, or nothing.
Men. PT-141 was first developed for erection problems. Early company-linked studies found stronger erections than placebo on a lab monitor, from a nasal spray and from shots. Nasal spray, 2004 · Shots, 2004 The men's nasal-spray program was withdrawn in 2017. The FDA review gives no reason. FDA review A 2008 study in men who did not respond to Viagra now carries an official "expression of concern" from its journal. Notice, 2023 A 2008 study in women by the same lead author was retracted after he did not answer a request for his original data. Retracted study
Weight. In one small company trial, women with obesity took it three times a day for 15 days — far more often than the label allows. They ate about 400 calories a day less. Diabetes, Obesity and Metabolism, 2022 The tirzepatide and kidney results are company press releases. Neither is peer-reviewed, and neither has results posted on its trial record. Tirzepatide, 2025 · Kidneys, 2024
What it is
PT-141 is a lab-made peptide: a chain of seven building blocks, most of them joined in a ring. It is modeled on a natural hormone called alpha-MSH. It switches on a family of receptors without picking one. It is strongest at MC1R, on the skin's pigment cells. Next comes MC4R, on nerve cells in the brain and spinal cord. FDA label
That explains a lot. MC1R switches on pigment: in animal safety studies, dogs' coats turned black. FDA review MC4R also helps control appetite, and the drug has been tested for weight. Diabetes, Obesity and Metabolism, 2022
It peaks in the blood about an hour after a shot, and half is gone in about 2.7 hours. FDA label
How it raises desire is unknown. The FDA label says so plainly. The FDA's own review called how it works in people "speculative." FDA review In female rats, it increased the behaviors rats use to invite sex, without changing how rewarding sex was. PNAS, 2004 A 2025 hamster study, with no company money, concluded it does not act on a key reward circuit in the brain. Neuropharmacology, 2025 In one brain-scan study of 31 women, a single dose raised desire for up to 24 hours and changed how some brain areas reacted to erotic images. It was small, and each woman got the drug only once. Journal of Clinical Investigation, 2022
What to expect
These side effects showed up more often than on placebo in the two big trials. FDA label
| Placebo | PT-141 | |
|---|---|---|
| Nausea | 1.3% | 40.0% |
| Flushing | 0.3% | 20.3% |
| Reaction where the shot went in | 8.4% | 13.2% |
| Headache | 1.9% | 11.3% |
| Throwing up | 0.2% | 4.8% |
| Stopped because of side effects | 2% | 18% |
Nausea is the main story. It usually began about half an hour after the shot and lasted about two and a half hours. Obstetrics & Gynecology, 2019 It was most common after the first dose, and 13% needed anti-nausea medicine. In a study of 228 women, an anti-nausea drug taken beforehand did not prevent it. FDA label
Four bigger things:
Blood pressure goes up after every dose. The top number rises by up to 6 points, peaking 2 to 4 hours after the shot, while heart rate drops. It usually settles within 12 hours. The label rules the drug out for uncontrolled high blood pressure or known heart disease. FDA label The daily blood-pressure study included just 2 women with treated high blood pressure. FDA review
Dark skin patches. In the big trials, 1% of women got darkened patches, including on the face, gums and breasts, against 0% on placebo. In a study with a dose every day, 38% got them within 8 days. Darker skin was more likely to be affected. FDA label In the big trials, the FDA saw the patches fade in about half of cases during follow-up. FDA review
Some pills may work less well. It can slow the stomach. In healthy women, one dose cut the peak blood level of naltrexone, taken as a pill, to about 37% of the level seen with placebo. FDA review The label says to avoid it with naltrexone pills for alcohol or opioid addiction. It also warns about pills that must reach a certain level to work, like antibiotics. FDA label
Pregnancy. In animal studies, at many times the human exposure, it caused pregnancy loss in dogs and slower development in baby mice. No safe level was found. Only 7 pregnancies happened in the trials, too few to judge. FDA label
One woman in the one-year study developed hepatitis, and her liver recovered after she stopped. No other cause was found, so the drug could not be ruled out. FDA label
Approved in the US, for one use
- United States: approved on June 21, 2019, as Vyleesi, a prescription injection pen, for low desire that causes distress in women before menopause. The label says it is not for men, women after menopause, or boosting performance, and to stop after 8 weeks if nothing has improved. Drugs@FDA · FDA label Palatin, which developed it, sold it to Cosette Pharmaceuticals in 2023. Palatin, 2023
- Europe: never approved. The EU drug agency's database has no record of it. EMA data, 2026
- Canada: not listed in Health Canada's drug database. Health Canada
- South Korea: not confirmed. A 193-person trial there finished in 2023 with no results posted. Korea's drug database lists no product. Trial record · Korea drug database
- China: not confirmed. A first sale in 2023 went through Hainan, a free trade zone where some imported drugs can be sold before national approval. Palatin, 2023
- Everywhere else: not checked.
The only approval we could confirm leaves out men. Weight loss and kidney disease are not approved anywhere.
What is still unknown
Approval did not close these questions:
- How it works.
- Whether the small gain matters in daily life.
- How it compares with the pill flibanserin, or with talk therapy. No head-to-head trial has been found.
- Anyone outside the trials. Nothing is established in men, women after menopause, children or older adults. The big trials were 86% white and 97% in the US.
- Anything past 24 weeks with a placebo group.
- Whether the skin patches always fade, and what years of blood-pressure bumps do.
- Pregnancy and breast milk. The FDA required a pregnancy registry and a breast-milk study. Pregnancy outcomes are still unknown, and the breast-milk study has posted no results. Approval letter · Trial record
What is in the bottle is not what was studied
One more thing.
Every result on this page came from bremelanotide made for clinical trials and given under a doctor's care. The only FDA-approved version is the Vyleesi pen. A vial sold as "PT-141" is not that product. Drugs@FDA
No study has ever shown that a product sold online as "PT-141" is the same thing. Not the same purity. Not the same strength. Not proof it is sterile. Not even proof it is the same molecule.
A forensic lab found bremelanotide in unknown samples police had seized along with steroids, all meant for the bodybuilding black market. The lab named what was in them. It did not measure strength or purity. Forensic study, 2021
So take every number on this page for what it is. It describes the drug the trials used, in the people they studied. It describes nothing else.
How to check a number yourself
You are going to see more numbers about this drug. In a reel. In a comment. On somebody's store page.
Here is how to tell a real one from a marketing one. Five questions. About ten seconds each.
1. Is there a link to a study?
A real number comes from a paper you can open. No link means it is a claim, not a result. Search the drug name on pubmed.gov yourself. With PT-141 you will find real trials — so also check the paper still stands. Two 2008 studies of it carry a retraction or a warning notice.
2. How big was it, and how long did it run?
Small studies swing. The desire result rests on 1,267 women over 24 weeks. The kidney claim rests on 16 people, and only 8 finished six months. Same kind of headline. Very different weight behind it.
3. Was there a group that got nothing?
The fake shot is the whole point. Here, 58% of women on the drug said it helped — but so did 36% on placebo. Without that group, you would never know. The one-year study and the kidney study had no placebo group at all.
4. How many people quit?
The number that tells you how a drug felt to take is further down than the headline. Here it is 18% on the drug, against 2% on placebo. Look for that line every time.
5. Who was in it, and who paid?
A number is only true for the people studied. The big results come from women with diagnosed low desire, average age 39, before menopause. Not men. Not healthy people chasing a boost. And the companies selling the drug paid for the big trials. That is normal. It matters more when an outside check finds most of the planned outcomes were never reported.
Now run those five on this page
Every number above links to the paper it came from. The study sizes are in the table. The placebo comparison is in the chart and the side-effect table. So is the quit rate. And you were told which figures are press releases, and which studies were retracted or flagged.
The claims for PT-141 outside its one approved use — for men, for weight, for tanning — have no big, reliable trial behind them.
That is the whole difference: a number you can check, and a number you are asked to believe.
This page has a date on it, near the top. When new studies publish, this page changes.
Read the studies yourself
- Two phase 3 trials, Obstetrics & Gynecology 2019 — the main one, free to read
- One-year study, 2019 · dose-finding trial, 2016
- Independent reanalysis, 2021 · unpublished outcomes, 2024
- FDA label · FDA review · approval letter · Drugs@FDA
- Brain-scan study, 2022 · rat study, 2004 · hamster study, 2025
- Men, nasal spray, 2004 · men, shots, 2004 · retracted study · expression of concern
- Weight trials, 2022 · tirzepatide press release · kidney press release
- Forensic study, 2021 · breast-milk study record · Korean trial record
- Sale to Cosette · first sale in China · EMA data · Health Canada · Korea drug database
Everything above describes what clinical trials gave to enrolled patients under a doctor's care. This is not advice, a plan, or instructions. In the US, bremelanotide is approved only as the prescription medicine Vyleesi, for one use in women. Research compounds are not for human or animal use.