Lithium and Olanzapine and fluoxetine interaction
Lithium and Olanzapine and fluoxetine: both prescribing labels flag this combination with the strongest language, such as a contraindication, a boxed warning, or an instruction to avoid it.
Do not combine without a prescriber's guidance. The label language below is the strongest FDA uses.
What the FDA labels say
From the Lithium (Lithium Carbonate) label · effective 2026-08-16
If concomitant use of lithium with other serotonergic drugs is clinically warranted, inform patients of the increased risk for serotonin syndrome and monitor for symptoms.
• Serotonergic Agents: Increased risk of serotonin syndrome when co-administered with lithium.
Serotonergic Drugs Clinical Impact: Concomitant use can precipitate serotonin syndrome.
If serotonin syndrome occurs, consider discontinuation of lithium and/or concomitant serotonergic drugs [see Warnings and Precautions ( 5.6 )] .
• Encephalopathic Syndrome: Increased risk in patients treated with lithium and an antipsychotic.
From the Olanzapine and fluoxetine label · effective 2026-03-31
If concomitant use of olanzapine and fluoxetine capsules with other serotonergic drugs is clinically warranted, patients should be made aware of a potential increased risk for serotonin syndrome, particularly during treatment initiation and dose increases ( 5.6 )
If concomitant use of olanzapine and fluoxetine capsules with other serotonergic drugs is clinically warranted, inform patients of the increased risk for serotonin syndrome and monitor for symptoms.
Lithium — Multiple doses of olanzapine did not influence the pharmacokinetics of 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.
Taking more than these two? Interactions stack. Check your whole list at once; it stays in your browser.
Open in the checkerNot medical advice. Interaction Checker quotes FDA label text and NIH fact sheets. Whether an interaction matters for you depends on doses, timing, kidney and liver function, and other conditions. Confirm with a pharmacist or prescriber.