PT-141

AApproved (Rx, US)bremelanotideVyleesimelanocortin agonist
In one paragraphPT-141, sold as Vyleesi, is a melanocortin-receptor agonist approved in the United States in 2019 for premenopausal women with hypoactive sexual desire disorder. Two phase 3 trials in 1,267 women found statistically significant but small improvements in desire and distress scores against placebo. Nausea affected 40% of participants and 18% stopped because of side effects. Use in men, and for erectile function, is unapproved and far less studied.
Schematic 3D structure of PT-141
7 residues · cyclic melanocortin analogue · schematic
Overall gradeA Established
Human trials2 phase 3 RCTs (n=1,267)
Outcomes graded5
Last reviewed2 September 2026
EvidenceWhat it isHow it worksUnknownsRegulationQuestionsReferences

What the human research shows

One of the few peptides on this site with a genuine approval behind it — and a useful lesson in reading one. The effect is real and statistically significant. It is also small, in a narrow population, and comes with a side-effect burden that made nearly a fifth of participants stop.

OutcomeGradeEffect sizeHuman studiesWhere the evidence comes from
Sexual desire (premenopausal women, HSDD)AEstablishedSmall2 phase 3 RCTsRECONNECT studies, 24 weeks: FSFI desire-domain change +0.5 to +0.6 vs +0.2 on placebo. Statistically significant, clinically modest.1
Sexual distress (same population)AEstablishedSmall2 phase 3 RCTsSignificant reduction in distress score versus placebo on the co-primary endpoint.1
Erectile function / use in menCWeakSmallEarlier phase 2 workDeveloped originally for erectile dysfunction; intranasal programme was stopped over blood-pressure increases. The approved product and indication are for women.1
NauseaadverseAEstablishedLargePhase 340% vs 1% on placebo; caused discontinuation in 8%. Overall discontinuation for adverse events 18% vs 2%.1
Flushing and headacheadverseAEstablishedModeratePhase 3Flushing 20.3% vs 0.3%; headache 11.3% vs 1.9%; injection-site reactions 13.2% vs 8.4%.1
AMultiple good human trials, consistentBSome human trials, mostly consistentCFew or weak human studiesDAnimal or anecdotal onlyeffect size · red = adverse

Literature searched to 2 September 2026. Human studies only; animal and cell work informs the mechanism section and nothing else.

What it is

PT-141 is a synthetic peptide derived from melanotan II, itself an analogue of the hormone that controls skin pigmentation. Researchers noticed that melanotan II produced unexpected sexual arousal in early trials, and bremelanotide was developed to isolate that effect.

It acts in the brain rather than on blood vessels, which makes it mechanistically different from the erectile-dysfunction drugs. It is given as an on-demand injection about 45 minutes before anticipated activity, not daily.

How it is thought to work

It activates melanocortin receptors, particularly MC4R, in brain regions involved in sexual motivation. Because the pathway is central rather than vascular, it does not depend on blood flow — and also why nausea, a melanocortin effect, is so common.

What is still unknown

  • Effect and safety in men at the doses used off-label; the approved evidence is in premenopausal women.
  • Long-term use beyond the 24-week trials.
  • Blood-pressure effects with repeated dosing — the label limits use to eight doses a month.

Regulatory status

United States
Approved, prescription-only

Vyleesi, for acquired generalised HSDD in premenopausal women only.

European Union
Not authorised

No EU marketing authorisation; grey-market product is unlicensed.

United Kingdom
Not authorised

Not licensed by the MHRA.

Canada
Not authorised

No Health Canada authorisation.

Questions people actually ask

Does PT-141 work?
For its approved indication, yes, by a statistically significant but small margin: desire scores improved by about 0.5 points more than placebo on a scale where the clinical meaning of that difference is debated. It is approved because it beat placebo, not because the effect is large.
Can men use PT-141?
It is not approved for men. The original erectile-dysfunction programme was halted over blood-pressure increases with the intranasal formulation. Off-label use in men rests on far weaker evidence than the approval implies.
Why does it cause so much nausea?
Melanocortin receptors are involved in nausea pathways as well as arousal. Forty percent of trial participants experienced it, and 8% stopped because of it.

References

  1. 1
    VYLEESI (bremelanotide injection) US prescribing information — RECONNECT phase 3 studies (NCT02333071, NCT02338960).FDA label, initial US approval 20191,267 premenopausal women across two 24-week trials; efficacy and adverse-event figures on this page come from the label.

Change log

  • 2026-09-02Initial publication from the FDA label and phase 3 programme.