Atomoxetine and Fluoxetine Interaction
Drug interaction information between Atomoxetine and Fluoxetine.
Atomoxetine and Fluoxetine have a documented minor interaction in FDA labeling.
FDA drug labeling documents a minor-severity interaction between Atomoxetine 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 blocks the liver enzyme that breaks down atomoxetine, which causes the levels of atomoxetine in your blood to rise significantly.
What To Do
Your doctor may need to lower your dose of atomoxetine to prevent side effects.
FDA Label Information
7.2 Effect of CYP2D6 Inhibitors on Atomoxetine In extensive metabolizers (EMs), inhibitors of CYP2D6 (e.g., paroxetine, fluoxetine, and quinidine) increase atomoxetine steady-state plasma concentrations to exposures similar to those observed in poor metabolizers (PMs). In EM individuals treated with paroxetine or fluoxetine, the AUC of atomoxetine is approximately 6- to 8-fold and C ss, max is about 3- to 4-fold greater than atomoxetine alone.
Atomoxetine Also Interacts With
- Albuterol moderate
- Omeprazole minor
- Methylphenidate minor
- Warfarin minor
- Diazepam minor
Fluoxetine Also Interacts With
- Aspirin major
- Warfarin major
- Olanzapine major
- Pimozide major
- Thioridazine major
Frequently Asked Questions
Can I take Atomoxetine and Fluoxetine together?
This is a minor interaction. Your doctor may need to lower your dose of atomoxetine to prevent side effects.
How serious is the interaction between Atomoxetine and Fluoxetine?
This interaction is classified as "minor" severity by the FDA. Minor interactions are unlikely to cause significant problems but should still be mentioned to your healthcare provider.
Why do Atomoxetine and Fluoxetine interact?
Fluoxetine blocks the liver enzyme that breaks down atomoxetine, which causes the levels of atomoxetine in your blood to rise significantly.
Understanding the Atomoxetine and Fluoxetine Interaction
FDA-approved prescribing information for these two drugs flags their combination as a minor-severity interaction. Atomoxetine belongs to the Selective Norepinephrine Reuptake Inhibitor 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 blocks the liver enzyme that breaks down atomoxetine, which causes the levels of atomoxetine in your blood to rise significantly. 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. Atomoxetine has 15 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 lower your dose of atomoxetine to prevent side effects. 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 Atomoxetine 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.