Fluoxetine with Fluvoxamine Interaction Details

Brand Names Associated with Fluoxetine

Brand Names Associated with Fluvoxamine

Medical Content Editor Dr. Brian Staiger, PharmD
Last updated Nov 11, 2023

Interaction Effect

Increased fluvoxamine exposure and increased risk of serotonin syndrome (hypertension, hyperthermia, myoclonus, mental status changes)

Interaction Summary

Concurrent use of fluoxetine (an SSRI and potent CYP2D6 inhibitor) with fluvoxamine (an SSRI and CYP2D6 substrate) may increase fluvoxamine exposure, result in additive serotonergic effects, and increase the risk of serotonin syndrome. If concomitant use of fluoxetine and fluvoxamine is required, monitor for signs and symptoms of serotonin syndrome. Symptoms of serotonin syndrome include neuromuscular abnormalities (including hyperreflexia, tremor, muscle rigidity, clonus, peripheral hypertonicity, and shivering), autonomic hyperactivity (including tachycardia, mydriasis, diaphoresis, the presence of bowel sounds, and diarrhea), and mental status changes (including agitation and delirium). Serotonin syndrome can be life-threatening . If serotonin syndrome develops, discontinue fluoxetine and fluvoxamine and provide supportive care as necessary 

Severity

Major

Onset

Unspecified

Evidence

Theoretical

How To Manage Interaction

The concomitant use of fluoxetine, a potent CYP2D6 inhibitor, with fluvoxamine, a CYP2D6 substrate, should be undertaken with caution as this may increase fluvoxamine exposure. Coadministration of these 2 SSRIs may also result in additive serotonergic effects and may increase the risk of serotonin syndrome. If concomitant use is necessary, discuss the risks of serotonin syndrome with the patient and monitor closely for symptoms of serotonin syndrome (mental status changes, autonomic instability, neuromuscular symptoms, seizures, and gastrointestinal symptoms), especially during treatment initiation and dose increases. If serotonin syndrome develops, discontinue fluoxetine and fluvoxamine and initiate supportive care.

Mechanism Of Interaction

Inhibition of CYP2D6-mediated metabolism of fluvoxamine by fluoxetine; additive serotonergic effect

Fluoxetine Overview

• Fluoxetine is used to treat depression, obsessive-compulsive disorder (bothersome thoughts that won't go away and the need to perform certain actions over and over), some eating disorders, and panic attacks (sudden, unexpected attacks of extreme fear and worry about these attacks). Fluoxetine is also used to relieve the symptoms of premenstrual dysphoric disorder, including mood swings, irritability, bloating, and breast tenderness. It is also used along with olanzapine (Zyprexa) to treat depression that did not respond to other medications and episodes of depression in people with bipolar I disorder (manic-depressive disorder; a disease that causes episodes of depression, episodes of mania, and other abnormal moods). Fluoxetine is in a class of medications called selective serotonin reuptake inhibitors (SSRIs). It works by increasing the amount of serotonin, a natural substance in the brain that helps maintain mental balance.

Fluvoxamine Overview

• Fluvoxamine is used to treat obsessive-compulsive disorder (bothersome thoughts that won't go away and the need to perform certain actions over and over) and social anxiety disorder (extreme fear of interacting with others or performing in front of others that interferes with normal life). Fluvoxamine is in a class of medications called selective serotonin reuptake inhibitors (SSRIs). It works by increasing the amount of serotonin, a natural substance in the brain that helps maintain mental balance.

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Definitions

Severity Categories

Contraindicated

These drugs, generally, should not be used together simultaneously due to the high risk of severe adverse effects. Combining these medications can lead to dangerous health outcomes and should be strictly avoided unless otherwise instructed by your provider.

Major

This interaction could result in very serious and potentially life-threatening consequences. If you are taking this drug combination, it is very important to be under close medical supervision to minimize severe side effects and ensure your safety. It may be necessary to change a medication or dosage to prevent harm.

Moderate

This interaction has the potential to worsen your medical condition or alter the effectiveness of your treatment. It's important that you are monitored closely and you potentially may need to make adjustments in your treatment plan or drug dosage to maintain optimal health.

Minor

While this interaction is unlikely to cause significant problems, it could intensify side effects or reduce the effectiveness of one or both medications. Monitoring for changes in symptoms and your condition is recommended, and adjustments may be made if needed to manage any increased or more pronounced side effects.

Onset

Rapid: Onset of drug interaction typically occurs within 24 hours of co-administration.

Delayed: Onset of drug interaction typically occurs more than 24 hours after co-administration.

Evidence

Level of documentation of the interaction.

Established: The interaction is documented and substantiated in peer-reviewed medical literature.

Theoretical: This interaction is not fully supported by current medical evidence or well-documented sources, but it is based on known drug mechanisms, drug effects, and other relevant information.

How To Manage The Interaction

Provides a detailed discussion on how patients and clinicians can approach the identified drug interaction as well as offers guidance on what to expect and strategies to potentially mitigate the effects of the interaction. This may include recommendations on adjusting medication dosages, altering the timing of drug administration, or closely monitoring for specific symptoms.

It's important to note that all medical situations are unique, and management approaches should be tailored to individual circumstances. Patients should always consult their healthcare provider for personalized advice and guidance on managing drug interactions effectively.

Mechanism Of Interaction

The theorized or clinically determined reason (i.e., mechanism) why the drug-drug interaction occurs.

Disclaimer: The information provided on this page is for informational purposes only and should not be considered medical advice. Always consult with a qualified healthcare professional regarding your specific circumstances and medical conditions.

Where Does Our Information Come From?

Information for our drug interactions is compiled from several drug compendia, including:

• Gold Standard Drug Database
• Micromedex
• Lexicomp
• DrugBank

The prescribing information for each drug, as published on DailyMED, is also used. 

Individual drug-drug interaction detail pages contain references specific to that interaction. You can click on the reference number within brackets '[]' to see what reference was utilized.

The information posted is fact-checked by HelloPharmacist clinicians and reviewed quarterly.