PT-141 myths: what the research does not show

Sexual Health & Intimacy Research

PT-141, also called bremelanotide, is a synthetic melanocortin receptor agonist whose main evidence is two phase 3 trials in premenopausal women, with statistically significant but modest results. This page compares the common claims with those trials and with the published criticism of them.

Myth: PT-141 is the female Viagra

False on the mechanism. PT-141 is an analogue of the hormone alpha-MSH and binds the melanocortin type 4 receptor, which is thought to influence brain pathways involved in sexual response. A 2019 approval review describes it in those terms. So its proposed action is in the brain, and the comparison with a drug acting on blood flow misleads.

Myth: PT-141 is a proven desire booster

Partly true, and the size matters. Both phase 3 trials met their main measures, which is a real result. The gains were small, though: 0.35 on the desire score. A 2021 Drug and Therapeutics Bulletin review reported no added enjoyable sexual experiences. A 2024 reanalysis questioned how well the measures were validated and called the benefits statistically modest. The trial authors and these critics read the same data differently, and both views are on the record.

Myth: PT-141 is approved for anyone with low libido

False. The 2019 US approval covers one group: premenopausal women with acquired, generalized hypoactive sexual desire disorder that causes marked distress or relationship difficulty. It does not extend to men, to women after menopause or to a general wish for more desire. Approval of that one pharmaceutical product says nothing about research-grade PT-141.

Myth: PT-141 works just as well for men

Not established. The 2008 trial of 342 men with erectile dysfunction reported a clear difference from placebo and more drug-related adverse effects. It remains a single study, and its authors said further work was needed before final conclusions. The 2019 approval did not include men, and we found no phase 3 programme in men.

Myth: PT-141 has no real side effects

False. In the integrated phase 3 data of 1,247 women, nausea affected 40.0% against 1.3% on placebo, flushing 20.3% against 1.3%, and headache 11.3% against 1.9%. Most events were mild to moderate. Small, short-lived rises in blood pressure were recorded, and the authors advised caution in people at cardiovascular risk. Only 70% of the bremelanotide group moved on to the open-label phase, compared with 87% on placebo.

Myth: PT-141 has nothing to do with skin colour

False. Focal darkening of the skin was rare in the main trials. It occurred in more than one third of subjects in a study of up to 16 consecutive days, according to the 2022 safety review. PT-141 is not a tanning compound, and no trial we read tested it for that purpose, but a pigment effect has been recorded.

Myth: PT-141 is a hidden weight loss peptide

Not shown. Because the same receptor family affects appetite, two small phase 1 trials looked at women with obesity. In one, weight fell 1.3 kg more than placebo over 16 days. In the other, only 15 of 27 completed all phases. Those are brief studies of intake and weight, and they say nothing about lasting loss.

What PT-141 cannot promise

PT-141 has a genuine human trial record, but that record is narrow and the size of the effect is disputed.

• It cannot promise a noticeable change in desire; average trial gains were small.
• It cannot promise the same result in men; that rests on one trial.
• It cannot promise comfort: about four in ten women in the trials reported nausea.
• It cannot promise lasting benefit; only 272 of 684 completed the 52-week extension.

Where the evidence stands

Bremelanotide has a US approval for one narrow group of premenopausal women, granted in 2019 and criticised in published reviews. PT-141 is not an approved medicine in Canada for general libido, for men, or for skin or weight uses. Research-grade PT-141 is a separate material from that approved product and is supplied for laboratory research.

Related reading. See the PT-141 studies in more detail, our PT-141 research notes and how long PT-141 lasts in storage.

Frequently asked questions

Is PT-141 the same as bremelanotide?

They are two names for the same peptide. The US approval applies to one pharmaceutical product, and research-grade PT-141 is a separate material that is not an approved medicine.

How large was the effect in the PT-141 trials?

Across two phase 3 trials, the desire score rose 0.35 more than placebo and distress fell 0.33 more. Both results were statistically significant, and independent reviewers have described them as modest.

Has PT-141 been tested in men?

Yes, but far less than in women. One randomized trial of 342 men with erectile dysfunction reported a difference from placebo, and its authors said more research was needed.

Sources: Kingsberg SA, Clayton AH, Portman D, et al. Bremelanotide for the Treatment of Hypoactive Sexual Desire Disorder: Two Randomized Phase 3 Trials. Obstet Gynecol. 2019. PMID 31599840. Safarinejad MR, Hosseini SY. Salvage of sildenafil failures with bremelanotide: a randomized, double-blind, placebo controlled study. J Urol. 2008. PMID 18206919. Spielmans GI, Ellefson EM. Small Effects, Questionable Outcomes: Bremelanotide for Hypoactive Sexual Desire Disorder. J Sex Res. 2024. PMID 36809187. Dhillon S, Keam SJ. Bremelanotide: First Approval. Drugs. 2019. PMID 31429064. Mintzes B, Tiefer L, Cosgrove L. Bremelanotide and flibanserin for low sexual desire in women: the fallacy of regulatory precedent. Drug Ther Bull. 2021. PMID 34642243. Clayton AH, Kingsberg SA, Portman D, et al. Safety Profile of Bremelanotide Across the Clinical Development Program. J Womens Health (Larchmt). 2022. PMID 35147466. Spana C, Jordan R, Fischkoff S. Effect of bremelanotide on body weight of obese women: Data from two phase 1 randomized controlled trials. Diabetes Obes Metab. 2022. PMID 35170192. Simon JA, Kingsberg SA, Portman D, et al. Long-Term Safety and Efficacy of Bremelanotide for Hypoactive Sexual Desire Disorder. Obstet Gynecol. 2019. PMID 31599847.