Flibanserin

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Flibanserin

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Medically reviewed

Laura Arias

Last updated on 22/12/2025

This page provides general, reference-level information compiled from official medical sources. It is not a substitute for professional medical advice, diagnosis, or treatment. For decisions about your health, please consult a qualified healthcare professional.

Overview of Flibanserin

Property Description
Active ingredient Flibanserin
Form Oral tablet
Pharmacological class Serotonin Receptor Modulator / Miscellaneous CNS Agent
Common use Treatment of acquired, generalized HSDD
Origin Synthetic benzimidazolone derivative

What is Flibanserin, and What is its General Purpose?

Flibanserin is a prescription-only medicine developed as a synthetic benzimidazolone derivative administered via the oral tablet route. Its general therapeutic purpose is to address the acquired, generalized low sexual desire, known as Hypoactive Sexual Desire Disorder (HSDD), that causes marked personal distress in adult pre-menopausal women. The substance's value is recognized for its role in addressing the distressing lack of desire in its target population.

Pharmacological Classification and Composition

The sole active compound is Flibanserin. This substance is classified as a Miscellaneous Central Nervous System Agent and belongs to the Pharmacological class of Serotonin Receptor Modulators, distinguishing it as a non-hormonal agent. This approach is considered first-in-class for its indication. Its specific action is dual: it functions as a Serotonin 5-HT₁A receptor agonist and a Serotonin 5-HT₂A receptor antagonist. This complex dual action on neurotransmitters is the basis of its function. This mechanism signifies that the medication works by rebalancing key chemical signals in the brain.

How Flibanserin Differs from Hormonal Therapies

Flibanserin’s function focuses on modulating the balance of neurotransmitters—namely serotonin, dopamine, and norepinephrine—within the brain regions associated with sexual motivation. This approach is fundamentally different from hormonal treatments or endocrine therapies, which act on systemic hormone levels. The medication is distinctively positioned for its daily administration to maintain a consistent neurochemical environment, contrasting with as-needed sexual health treatments. The value of this neurochemical approach lies in providing a specific, centrally-acting alternative that targets the neurobiological underpinnings of low desire, rather than peripheral or generalized physiological responses.

Regulatory References

  1. U.S. National Library of Medicine

What side effects are possible with Flibanserin?

Possible Side Effects and Safety Information

The safety profile of Flibanserin, as documented in official regulatory labeling, highlights adverse reactions primarily affecting the central nervous system (CNS) and potential risks of severe hypotension and syncope.

Adverse Reactions by Frequency

Side effects are classified by their documented incidence:

  • Very Common (occurring in 10% or more of users) adverse reactions include somnolence (sleepiness), dizziness, and nausea.
  • Common (occurring in 1% to less than 10% of users) reactions include fatigue, sedation, vertigo, dry mouth, and various gastrointestinal issues such as constipation and abdominal pain.

Serious Safety Risks and Contraindications

The most serious safety concerns are severe hypotension (low blood pressure) and syncope (fainting or loss of consciousness), which are documented risks that can be exacerbated by increased plasma concentrations of the medicine. Due to these risks, the medicine is contraindicated (absolutely prohibited) for use in patients with any degree of hepatic impairment (liver damage), with alcohol, and with moderate or strong CYP3A4 inhibitors.

Time- and Population-Specific Safety Patterns

The risk of hypotension, syncope, and CNS depression is officially documented as increased if the medication is taken during waking hours. Use is not recommended for geriatric patients (age 55 and older) and has not been established for pediatric patients (under 18 years old). These classifications reflect the regulatory approach to managing the risks associated with this medication.

Overdose and Emergency Response

The official regulatory documents define the overdose profile for Flibanserin primarily by severe physiological effects that necessitate immediate medical attention. High systemic exposure is characterized by pronounced Central Nervous System (CNS) Depression, including excessive sleepiness (somnolence) and sedation. The most critical concern is severe hypotension (very low blood pressure) and syncope (fainting), which carries an associated risk of accidental injury.


Required Emergency Actions

In cases of overdose or severe exposure, individuals must follow specific emergency instructions. If you experience lightheadedness or dizziness (pre-syncope), you should immediately lie supine and promptly seek medical help if symptoms do not resolve. Call emergency services (such as 911) immediately if the affected individual has collapsed, is having a seizure, is having trouble breathing, or cannot be awakened. Contacting the Poison Control Helpline is also required.


Management and Risk Considerations

Management of flibanserin overdose relies solely on symptomatic and supportive treatment, as regulatory documents state that no specific antidote is known. The risk of severe hypotension and syncope is significantly amplified in patients with hepatic impairment, leading to the drug being strictly contraindicated in this population. Postmarketing reports also highlight unique severe risks, including respiratory depression and failure, following accidental ingestion by children.

Therapeutic Uses of Flibanserin

What Flibanserin Treats: Main Uses and Benefits

Flibanserin is commonly used in the symptomatic management of acquired, generalized Hypoactive Sexual Desire Disorder (HSDD) in adult pre-menopausal women who experience marked personal distress as a result of their low sexual desire. This therapy is relevant in situations where symptoms cluster into a pattern of recurrent or persistent deficiency of sexual fantasies and desire for sexual activity, provided the condition is acquired and generalized.

The therapeutic approach is relevant for easing symptomatic manifestations when low desire causes marked personal distress or significant interpersonal difficulty. The core indications include managing the deficient sexual desire, easing associated discomfort, and addressing functional stability related to sexual desire. This medication contributes to easing the overall symptom load during periods of heightened symptoms.

“The therapeutic benefit may help ease the emotional strain and functional discomfort associated with HSDD.”

Quick Fact: Support for Symptom Management
Symptom Category: Deficient sexual desire and associated psychological distress.
Goal: Helps maintain a sense of stability when symptoms are more noticeable.
Usage Context: Used for chronic, generalized lack of desire in adult pre-menopausal women.

Regulatory References

  1. National Institutes of Health (NIH) DailyMed

Eligibility and Restrictions for Use

Who can and cannot use Flibanserin?

Flibanserin use is governed by strict population-based eligibility rules established by regulatory authorities. The medication is explicitly indicated only for adult pre-menopausal women diagnosed with acquired, generalized Hypoactive Sexual Desire Disorder (HSDD) that causes marked personal distress.

Absolute Contraindications

Flibanserin is contraindicated and must not be used in the following patient populations due to safety risks:

  • Patients with any degree of hepatic impairment (liver problems).
  • Women who are pregnant or breastfeeding.
  • Patients with a known hypersensitivity to flibanserin or any component.

Use Limitations and Restrictions

Flibanserin is not indicated for treatment in men or postmenopausal women. Additionally, its safety and efficacy have not been established in pediatric patients (under 18) or geriatric patients, and use is generally not recommended in these groups. While renal impairment is not an absolute contraindication, the medication is only approved for HSDD that is not caused by other medical or psychiatric conditions.

What should I know about interactions with other medicines?

The interaction profile of Flibanserin is defined by pharmacokinetic and pharmacodynamic restrictions documented in government regulatory labeling.

Contraindicated Combinations and Conditions

Co-administration is formally contraindicated with alcohol/ethanol due to a significantly increased risk of severe hypotension and syncope. Use is also prohibited with Moderate or Strong CYP3A4 Inhibitors, as these agents increase the drug’s plasma concentration by inhibiting its primary metabolic pathway. Furthermore, the medicine is contraindicated for patients with any degree of hepatic impairment due to the resulting significant increase in drug exposure.

Pharmacokinetic and Timing Restrictions

Flibanserin is primarily metabolized by the CYP3A4 enzyme. Co-administration with strong CYP3A4 inducers, such as rifampin, is not recommended because they substantially reduce the drug’s exposure, which may diminish efficacy. A mandatory washout period is required when initiating or discontinuing a Moderate or Strong CYP3A4 Inhibitor. Specific timing rules apply to alcohol consumption: the dose must be separated by at least two hours from minimal alcohol and skipped entirely after heavier alcohol consumption.

Other Documented Interactions

The medicine is documented to inhibit the drug efflux transporter P-glycoprotein (P-gp). This may lead to increased plasma levels of co-administered P-gp substrate medicines, such as digoxin. The ingestion of grapefruit or grapefruit juice is documented to increase flibanserin exposure and should be avoided. Co-administration with other Central Nervous System (CNS) depressants may result in additive pharmacodynamic effects like enhanced somnolence.

Mechanism of Action

Dual Receptor Modulation and Monoamine Rebalancing

Flibanserin functions as a Multifunctional Serotonin Agonist and Antagonist (MSAA), primarily targeting the Serotonin 5-HT1A and 5-HT2A receptors in the central nervous system. It exhibits agonistic activity at the 5-HT1A receptor and antagonistic activity at the 5-HT2A receptor. This dual molecular action initiates a cascade that results in a net shift in central monoamine concentrations, specifically promoting a functional decrease in the inhibitory neurotransmitter, serotonin (5-HT), and a functional increase in the excitatory neurotransmitters, dopamine (DA) and norepinephrine (NE), within specific neural circuits.

Modulating Central Monoaminergic Signaling

This neurochemical shift adjusts the basal balance of inhibitory versus excitatory signaling within monoaminergic projection pathways. The consequence of this mechanism is a shift toward a state of enhanced central neural excitation, which reflects an alteration in baseline monoamine signaling patterns that govern motivational and arousal pathways.

Dosage and Administration Information

How to Use Flibanserin: Official Administration Guidelines

Flibanserin is administered as a 100 mg oral tablet taken once daily, with its administration principles defined to ensure consistent use. The dosage is fixed, and the timing of administration is an established procedural requirement.


Administration Scope

Feature Instruction Summary
Route of Administration Oral
Dosing Schedule 100 mg once daily
Mandatory Timing The dose must be taken at bedtime and is not to be taken during waking hours.
Missed-Dose Rule If a dose is missed at bedtime, the patient must skip the missed dose and take the next dose at bedtime the following day.
Duration of Use Treatment must be discontinued after 8 weeks if no improvement in symptoms is reported.
Population Exclusion The medication is not indicated for use in men or postmenopausal women.

Resulting Procedural Structure

The entire administration protocol for Flibanserin is structured around the required bedtime timing and the 100 mg fixed daily dose. This fixed-dosing frequency defines the primary use pattern. Procedural standards also define specific washout periods when initiating treatment following the cessation of moderate or strong CYP3A4 inhibitors, requiring a two-week delay before Flibanserin can be started. These procedural instructions establish the precise framework for how the drug is used in clinical practice.

Recent Clinical Evidence

Flibanserin: Recent Clinical Evidence

The efficacy and safety of flibanserin have been evaluated primarily in 24-week, randomized, placebo-controlled trials involving premenopausal women diagnosed with acquired, generalized hypoactive sexual desire disorder (HSDD). The drug was assessed using patient-reported outcomes that focused on three key measures:

  • Satisfying Sexual Events (SSEs): The monthly frequency of SSEs showed a statistically significant increase in participants receiving flibanserin compared to placebo, typically resulting in an average increase of about 0.5 to 1.0 event per month.
  • Sexual Desire: Scores on the Female Sexual Function Index (FSFI) desire domain showed a small but statistically significant improvement compared to placebo.
  • Distress Reduction: Measures of distress related to low sexual desire (e.g., FSDS-R Item 13) demonstrated a statistically significant decrease in distress for women taking flibanserin versus those on placebo.

Safety and Tolerability

Overall, the studies observed that a greater percentage of women receiving flibanserin reported clinically meaningful benefit compared to those on placebo (an increase of approximately 10% more responders). However, the trials also showed a higher incidence of specific adverse events with flibanserin, including:

Adverse Event (AE) Relative Risk vs. Placebo (Approx.)
Dizziness 4.0 times higher
Somnolence (Drowsiness) 4.0 times higher
Nausea 2.4 times higher
Fatigue 1.6 times higher

The most common adverse events were typically mild to moderate in intensity and often occurred within the first 14 days of treatment. Discontinuation rates due to adverse events were higher in the flibanserin group compared to the placebo group. Long-term safety and efficacy data beyond 24 weeks continue to be evaluated.

Key Studies & References

  1. Efficacy and safety of flibanserin in postmenopausal women with hypoactive sexual desire disorder: results of the SNOWDROP trial

Frequently Asked Questions (FAQ)

Common questions about Flibanserin (FAQ)

Q: How quickly should I expect Flibanserin to start working?

A: According to the official product information, clinical studies assessed the medicine's effects over a 24-week period. Official guidance advises evaluating treatment for discontinuation if no improvement in symptoms is reported after 8 weeks, indicating that benefit is assessed over the course of several weeks to months.

Q: Does Flibanserin increase libido in all women?

A: Clinical trials showed a statistically significant number of women experienced an increase in sexual desire and satisfying sexual events compared to those who took a placebo. However, clinical data indicates that not every individual who takes the medication will respond or see a therapeutic benefit.

Q: Can Flibanserin be taken with birth control pills?

A: Regulatory documents indicate that oral contraceptives are considered weak inhibitors of the CYP3A4 enzyme, which metabolizes Flibanserin. Since oral contraceptives may increase the concentration of Flibanserin, this combination may lead to a higher risk of adverse reactions, as stated in the product information.

Q: Does Flibanserin interact with any common anti-anxiety medications?

A: Flibanserin acts as a Central Nervous System (CNS) depressant. When taken with other medicines that also cause CNS depression, which can include some anti-anxiety or sedative medications, there is an increased risk of enhanced effects like excessive sleepiness or sedation.

Q: Is Flibanserin safe for women who are going through menopause?

A: The product label specifies that Flibanserin is indicated only for premenopausal women who have been diagnosed with Hypoactive Sexual Desire Disorder (HSDD). The safety and effectiveness of the medicine have not been established in postmenopausal women.

Q: How long can a woman safely stay on Flibanserin treatment?

A: Official administration guidelines state that if a patient reports no improvement in symptoms after the first 8 weeks of treatment, the medication must be discontinued. For continued use past the initial assessment period, ongoing treatment is generally managed and monitored by a healthcare professional.

Q: Does Flibanserin help with physical arousal or only desire?

A: The clinical studies supporting the drug's approval focused on psychological elements of sexuality. The primary endpoints in the clinical studies focused on desire, distress, and satisfying sexual events, rather than measures of direct physical arousal.

Q: How does the doctor determine if Flibanserin is appropriate for a patient?

A: The drug is only indicated for premenopausal women who have been diagnosed with HSDD, which is defined as low sex drive causing marked personal distress. A healthcare provider must confirm the low desire is not due to another medical condition, psychiatric issue, or concurrent medication use.

Q: Does Flibanserin cause weight gain or weight loss?

A: The adverse reactions documented in the clinical trial summaries do not list weight gain or weight loss among the most common or very common side effects associated with Flibanserin.

Q: Can Flibanserin affect my mood or cause depression?

A: Adverse reactions related to mood disturbances or depression are not listed among the most common side effects in the official safety summaries. Furthermore, clinical trials did not show an increased risk of suicidal thoughts or behavior associated with the use of this drug.

Q: Are there any long-term side effects of taking Flibanserin?

A: Official product information states that safety and efficacy data from trials are based on up to 24 weeks of treatment. Longer-term effects and safety profiles continue to be assessed.

Q: Are there generic versions of Flibanserin available?

A: Yes, regulatory drug status information confirms that generic versions of the flibanserin tablet are currently available in the United States.

Q: Does Flibanserin change testosterone or estrogen levels?

A: Flibanserin is classified as a non-hormonal medicine. Its mechanism of action involves modulating neurotransmitters in the brain and is not known to directly alter systemic hormone levels such as testosterone or estrogen.

Q: Were there any major studies that supported the approval of Flibanserin?

A: The drug's approval was supported by several key clinical studies. Specifically, three 24-week, randomized, placebo-controlled trials were conducted involving premenopausal women diagnosed with Hypoactive Sexual Desire Disorder (HSDD).

Q: Is Flibanserin approved in countries outside of the US?

A: Yes, Flibanserin, marketed under the brand name Addyi, has been approved for use in other regulatory jurisdictions, such as Canada, for the treatment of HSDD in premenopausal women.

Q: Does stopping Flibanserin cause any withdrawal symptoms?

A: Clinical study data, including those from randomized withdrawal trials, did not observe specific withdrawal reactions following the discontinuation of flibanserin.

Q: Is it necessary to take Flibanserin exactly at the same time every night?

A: Official instructions require the drug to be taken once daily at bedtime, as taking it during waking hours increases the risk of severe side effects such as low blood pressure and fainting.

Q: Does Flibanserin have any impact on fertility?

A: There are no adequate studies on Flibanserin in pregnant women, and the specific effects on human fertility are unknown. Animal studies showed fetal toxicity only at high doses associated with toxicity in the mother.

Q: How is Flibanserin different from an antidepressant?

A: Flibanserin is approved as a Serotonin Receptor Modulator exclusively for treating Hypoactive Sexual Desire Disorder (HSDD) in premenopausal women. It is not approved for treating psychiatric conditions like depression, but rather for Hypoactive Sexual Desire Disorder (HSDD).

Q: Can women with liver problems take Flibanserin?

A: Official regulatory documents state that Flibanserin is contraindicated (absolutely prohibited) for use in patients with any degree of liver problems. This is a critical safety measure due to a significantly increased risk of severe low blood pressure and fainting.

Q: What clinical trials looked at Flibanserin's safety?

A: Safety was continually evaluated during the main efficacy studies. In addition, the FDA required specific post-marketing studies, such as those examining drug-drug interactions and simulated driving performance, to further assess the drug's safety profile.

Q: Is it okay to drive the morning after taking Flibanserin?

A: Regulatory-mandated simulated driving studies indicated that when Flibanserin is taken at bedtime, it did not show impairment on next-day driving performance or cognitive function compared to placebo.

How should Flibanserin be stored and disposed of?

Storage and Disposal of Flibanserin

Flibanserin tablets must be stored according to specific regulatory conditions to maintain stability.


Official Storage Requirements

Flibanserin must be kept at controlled room temperature, specifically 25 C (77 F), with permitted excursions between 15 C and 30 C. The product must be stored in its original, tightly closed container and must be protected from light, excess heat, and moisture. It is explicitly stated that the medicine must not freeze.

For safety, Flibanserin must be stored out of the sight and reach of children.


Disposal Instructions

Expired or unused tablets require proper disposal. Regulatory guidance recommends consulting a pharmacist or healthcare professional for the correct method. The use of a drug take-back program is generally advised for discarding the medication.

Attention! Always consult to a doctor or pharmacist before using pills or medicines.

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