Fluoxetine and Lithium Interaction
Drug interaction information between Fluoxetine and Lithium.
Fluoxetine and Lithium have a documented minor interaction in FDA labeling.
FDA drug labeling documents a minor-severity interaction between Fluoxetine and Lithium. 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 lithium levels in your blood to go up or down unpredictably. It can also increase the risk of a serious reaction to brain chemicals.
FDA Label Information
Lithium — There have been reports of both increased and decreased lithium levels when lithium was used concomitantly with fluoxetine. Cases of lithium toxicity and increased serotonergic effects have been reported. Lithium levels should be monitored when these drugs are administered concomitantly [see Warnings and Precautions (5.2) ] .
Fluoxetine Also Interacts With
- Aspirin major
- Warfarin major
- Olanzapine major
- Pimozide major
- Thioridazine major
Lithium Also Interacts With
- Amlodipine/Benazepril major
- Risperidone major
- Amiloride moderate
- Amiodarone moderate
- Amlodipine/Valsartan moderate
Frequently Asked Questions
What SPL severity band is on file for Fluoxetine + Lithium?
Compiled FDA labeling labels this pair minor. That is a source-record field, not an individual medication-combination decision.
Which drug in this pair has the larger labeled-interaction portfolio?
Lithium has 90 labeled pairs on file vs Fluoxetine's 68. In the minor band specifically: Fluoxetine has 43 (also Ketoconazole, Moxifloxacin, Erythromycin, Imipramine); Lithium has 65 (also Aripiprazole, Asenapine, Canagliflozin, Candesartan).
What mechanism field is on file for Fluoxetine and Lithium?
Fluoxetine can cause lithium levels in your blood to go up or down unpredictably. It can also increase the risk of a serious reaction to brain chemicals.
Fluoxetine carries more major-labeled pairs than Lithium
SPL source-record counts only. This page's band is minor · classes on file: Fluoxetine (Selective Serotonin Reuptake Inhibitor (SSRI)); Lithium (Mood Stabilizer).
Fluoxetine has 6 major-labeled pairs vs Lithium's 2. This page itself is in the minor band, not the major band.
6 major · 19 moderate · 43 minor · 68 total
- Other minor peers for Fluoxetine
- Ketoconazole
- Moxifloxacin
- Erythromycin
- Imipramine
2 major · 23 moderate · 65 minor · 90 total
- Other minor peers for Lithium
- Aripiprazole
- Asenapine
- Canagliflozin
- Candesartan
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.