Fluoxetine and Olanzapine Interaction
Drug interaction information between Fluoxetine and Olanzapine.
Fluoxetine and Olanzapine have a documented major interaction in FDA labeling.
FDA drug labeling documents a major-severity interaction between Fluoxetine and Olanzapine. This page displays the available source-record category and label text. The category is not an individual risk estimate or medication-combination direction.
How They Interact
Fluoxetine can cause a small change in the amount of olanzapine that stays in your blood. This happens because fluoxetine interferes with how your body breaks down the other medication.
FDA Label Information
NSAIDs, Aspirin, Warfarin): May potentiate the risk of bleeding ( 7.4 ) Drugs Tightly Bound to Plasma Proteins: May cause a shift in plasma concentrations ( 7.6 , 7.7 ) Olanzapine: When used in combination with fluoxetine, also refer to the Drug Interactions section of the package insert for Symbyax ( 7.7 ) Drugs that Prolong the QT Interval: Do not use fluoxetine with thioridazine or pimozide. Olanzapine — Fluoxetine (60 mg single dose or 60 mg daily dose for 8 days) causes a small (mean 16%) increase in the maximum concentration of olanzapine and a small (mean 16%) decrease in olanzapine...
Fluoxetine Also Interacts With
- Aspirin major
- Warfarin major
- Pimozide major
- Thioridazine major
- Clonazepam major
Olanzapine Also Interacts With
- Tetrabenazine moderate
- Omeprazole minor
- Warfarin minor
- Diazepam minor
- Carbamazepine minor
Frequently Asked Questions
What SPL severity band is on file for Fluoxetine + Olanzapine?
Compiled FDA labeling labels this pair major. That is a source-record field, not an individual medication-combination decision.
Which drug in this pair has the larger labeled-interaction portfolio?
Fluoxetine has 68 labeled pairs on file vs Olanzapine's 26. In the major band specifically: Fluoxetine has 6 (also Aspirin, Warfarin, Pimozide, Thioridazine); Olanzapine has 1.
What mechanism field is on file for Fluoxetine and Olanzapine?
Fluoxetine can cause a small change in the amount of olanzapine that stays in your blood. This happens because fluoxetine interferes with how your body breaks down the other medication.
Fluoxetine carries more major-labeled pairs than Olanzapine
SPL source-record counts only. This page's band is major · classes on file: Fluoxetine (Selective Serotonin Reuptake Inhibitor (SSRI)); Olanzapine (Atypical Antipsychotic).
Fluoxetine has 6 major-labeled pairs vs Olanzapine's 1.
6 major · 19 moderate · 43 minor · 68 total
- Other major peers for Fluoxetine
- Aspirin
- Warfarin
- Pimozide
- Thioridazine
1 major · 1 moderate · 24 minor · 26 total
Olanzapine has no other major-band peer in this dataset besides Fluoxetine.
Sources: FDA Drug Labels (SPL) via openFDA (2026). This is for informational purposes only and is not medical advice. This registry does not provide individual medication-combination directions.
Read our methodology - how this data is sourced, computed, and verified.