Vyleesi (bremelanotide) works by activating receptors in the brain that are part of the body’s natural sexual desire pathway. It’s an injectable medication approved for premenopausal women with hypoactive sexual desire disorder, a persistent lack of sexual desire that causes personal distress. Unlike a daily pill, Vyleesi is used as needed, injected under the skin at least 45 minutes before anticipated sexual activity.
How It Activates the Brain’s Desire Pathway
Your brain has a family of receptors called melanocortin receptors, found primarily in the central nervous system. These receptors are involved in regulating appetite, skin pigmentation, and sexual desire. Vyleesi activates several of them, but the one that matters most at the therapeutic dose is the MC4R subtype.
MC4R receptors are concentrated in a specific part of the hypothalamus called the medial preoptic area, a region critical for female sexual function. When Vyleesi binds to these receptors, it triggers the release of dopamine, an excitatory brain chemical that increases sexual desire. In essence, the drug taps into the same excitatory pathway that melanocortins (the body’s own signaling molecules) use naturally during sexual arousal. It amplifies a signal your brain already has the wiring for, rather than creating an entirely new one.
How It Differs From Addyi
Vyleesi and Addyi (flibanserin) are both approved for low sexual desire in premenopausal women, but they work through completely different brain systems. Addyi targets serotonin receptors and is taken as a daily pill, requiring weeks of continuous use before any effect on desire builds up. Vyleesi activates melanocortin receptors and works on demand, used only when you want it. You don’t need to take it every day, and there are no alcohol restrictions like those associated with Addyi.
How You Use It
Vyleesi comes in a prefilled autoinjector, similar to devices used for allergy medications. You inject it under the skin of your abdomen or thigh at least 45 minutes before you anticipate sexual activity. The exact window of effectiveness after each dose hasn’t been pinned down in studies, so the FDA recommends that users figure out their own optimal timing based on how long the effect on desire lasts for them personally and how they tolerate any side effects.
You should not use more than one dose in a 24-hour period.
What Clinical Trials Found
Vyleesi was tested in two large Phase 3 randomized trials. Across both studies, women taking the drug had statistically significant increases in sexual desire and meaningful reductions in distress related to low desire compared to those on placebo. The improvements were consistent across both trials.
It’s worth setting realistic expectations. The effect is moderate. Vyleesi doesn’t create desire out of nothing. It nudges the brain’s existing excitatory pathway enough to produce a measurable, meaningful difference for many women, but it won’t work for everyone, and the degree of improvement varies.
Side Effects to Expect
Nausea is by far the most common side effect. In clinical trials, 40% of women who received up to eight monthly doses reported it. The nausea typically starts within an hour of injection and lasts about two hours. For many women it becomes less intense with repeated use, but it’s significant enough that some stop using the medication.
Vyleesi also causes a small, temporary increase in blood pressure, peaking within the first four hours after injection. The average rise is about 2 to 3 mmHg for both the top and bottom numbers. This resolves on its own within 12 hours and doesn’t require treatment. However, the drug is not recommended for women with uncontrolled high blood pressure or known cardiovascular disease because of this effect.
Some women also notice temporary darkening of the skin, particularly on the face and gums. This happens because the drug activates MC1R, the melanocortin receptor involved in pigmentation. The darkening is generally mild and tends to fade after stopping the medication, though it may not fully reverse in everyone.
Who It’s Approved For
Vyleesi is specifically approved for premenopausal women diagnosed with hypoactive sexual desire disorder. It is not approved for treating low desire caused by relationship problems, other medical conditions, medication side effects, or menopause. The diagnosis requires that the low desire is persistent, occurs across situations (not just with a specific partner), and causes meaningful personal distress. It is not approved for use in men.