Flibanserin is a medication approved in the United States for acquired, generalized hypoactive sexual desire disorder (HSDD) in certain premenopausal women. Unlike drugs used for male erectile dysfunction, it does not increase genital blood flow. Instead, it acts on neurotransmitters in the brain that influence sexual desire.

Mechanism of Action

Flibanserin works primarily by modulating serotonin, dopamine, and norepinephrine pathways in the brain.

Specifically, it:

• Acts as a 5-HT1A receptor agonist (stimulates these serotonin receptors)
• Acts as a 5-HT2A receptor antagonist (blocks these serotonin receptors)

The overall effect is thought to:

• Reduce serotonin activity in certain brain regions
• Increase dopamine levels
• Increase norepinephrine levels

This matters because:

• Serotonin tends to inhibit sexual desire in many people.
• Dopamine and norepinephrine are associated with motivation, reward, excitement, and sexual interest.

A simplified view is:

↓ Serotonin → ↑ Dopamine + ↑ Norepinephrine → ↑ Sexual Desire

What It Does Not Do

Flibanserin:

• Does not directly cause arousal
• Does not improve vaginal lubrication
• Does not create an immediate sexual response
• Does not work like Sildenafil or other erectile dysfunction drugs

It is intended to gradually improve baseline sexual desire over time.

How It Is Taken

• One tablet daily at bedtime.
• Not taken “as needed” before sex.
• Effects are typically evaluated after about 8 weeks of treatment.

Expected Benefits

Clinical trials found that some women experienced:

• Increased sexual desire
• More satisfying sexual events
• Reduced distress related to low sexual desire

The average benefit is generally considered modest, and not everyone responds.

Common Side Effects

The most common side effects include:

• Dizziness
• Sleepiness
• Fatigue
• Nausea
• Dry mouth

Because it can cause significant drowsiness, it is taken at bedtime.

Important Safety Considerations

Flibanserin can lower blood pressure and cause fainting, particularly:

• When combined with certain medications that inhibit the liver enzyme CYP3A4
• In people with liver impairment

Patients should always have their medication list reviewed before starting treatment.

Neurobiology in One Sentence

Flibanserin is essentially a centrally acting neurotransmitter modulator that attempts to restore the balance between inhibitory serotonin signaling and excitatory dopamine/norepinephrine signaling involved in sexual desire.