Haloperidol and Fluoxetine Interaction
Drug interaction information between Haloperidol and Fluoxetine.
Haloperidol and Fluoxetine have a documented moderate interaction in FDA labeling.
FDA drug labeling documents a moderate-severity interaction between Haloperidol and Fluoxetine. Major interactions are generally avoided, moderate ones may need monitoring or a dose adjustment, and minor ones are usually low-risk. This page shows the documented mechanism and guidance. Label-documented interactions are not a complete safety review, so always confirm your own medications with a pharmacist or doctor. Educational information, not medical advice.
How They Interact
Fluoxetine slows down the process that clears haloperidol from your system. This can cause the level of the antipsychotic drug to rise in your blood.
What To Do
Your doctor may need to reduce your dose of haloperidol. Monitor yourself closely for any new side effects while taking both medications.
FDA Label Information
Monoamine Oxidase Inhibitors (MAOIs): ( 2.9 , 2.10 , 4.1 , 5.2 ) Drugs Metabolized by CYP2D6: Fluoxetine is a potent inhibitor of CYP2D6 enzyme pathway ( 7.7 ) Tricyclic Antidepressants (TCAs): Monitor TCA levels during coadministration with fluoxetine or when fluoxetine has been recently discontinued ( 5.2 , 7.7 ) CNS Acting Drugs: Caution should be used when taken in combination with other centrally acting drugs ( 7.2 ) Benzodiazepines: Diazepam – increased t½, alprazolam - further psychomotor performance decrement due to increased levels ( 7.7 ) Antipsychotics: Potential for elevation...
Haloperidol Also Interacts With
- Tetrabenazine moderate
- Bromocriptine minor
- Bupropion minor
- Carbamazepine minor
- Clomipramine minor
Fluoxetine Also Interacts With
- Aspirin major
- Warfarin major
- Olanzapine major
- Pimozide major
- Thioridazine major
Frequently Asked Questions
Can I take Haloperidol and Fluoxetine together?
This is a moderate interaction. Your doctor may need to reduce your dose of haloperidol. Monitor yourself closely for any new side effects while taking both medications.
How serious is the interaction between Haloperidol and Fluoxetine?
This interaction is classified as "moderate" severity by the FDA. Moderate interactions may worsen your condition or change how your medications work.
Why do Haloperidol and Fluoxetine interact?
Fluoxetine slows down the process that clears haloperidol from your system. This can cause the level of the antipsychotic drug to rise in your blood.
Understanding the Haloperidol and Fluoxetine Interaction
FDA-approved prescribing information for these two drugs flags their combination as a moderate-severity interaction. Haloperidol belongs to the Typical Antipsychotic class and Fluoxetine belongs to the Selective Serotonin Reuptake Inhibitor (SSRI) class - two categories that can collide when co-prescribed. The mechanism described in FDA labeling is: Fluoxetine slows down the process that clears haloperidol from your system. Severity tiers matter: major flags generally advise avoidance, moderate flags often require monitoring or dose adjustment, and minor flags may only call for awareness.
Context around a specific patient determines real-world impact. Haloperidol has 14 total documented interactions on file in this dataset, and Fluoxetine has 68. Each additional medication compounds the interaction surface, which is why pharmacists run full-profile checks rather than evaluating one pair at a time. FDA-derived guidance for this pair is: Your doctor may need to reduce your dose of haloperidol. Timing of doses, renal and hepatic function, age, and other concurrent prescriptions all shape whether a labeled interaction matters clinically.
An interaction flag is not a verdict. A large share of labeled interactions are managed routinely in clinical practice, the fix may be as simple as spacing doses or adding a monitoring test. Others require the prescriber to choose a different medication entirely. This page surfaces FDA-sourced labeling and openFDA data for educational purposes only; it is not medical advice and cannot account for your full clinical picture. Never start, stop, or adjust either Haloperidol or Fluoxetine based on a web page, speak with your prescriber or pharmacist before making any change.
Sources: FDA Drug Labels (SPL) via openFDA (2026). This is for informational purposes only and is not medical advice. Always consult your healthcare provider about drug interactions.
Read our methodology - how this data is sourced, computed, and verified.