Drug interactions
Diazepam + Fluoxetine
Severity: Moderate
Diazepam and Fluoxetine: moderate interaction.
Last updated
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Fluoxetine and its metabolite norfluoxetine inhibit CYP2C19 and can raise diazepam levels and prolong its half-life. This may increase sedation and psychomotor impairment, and the effect lingers after fluoxetine is stopped.
What this interaction means in plain words
Diazepam and Fluoxetine can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Diazepam belongs to Musculoskeletal; Fluoxetine belongs to Central Nervous System.
Why it happens
Fluoxetine and norfluoxetine inhibit CYP2C19 (and CYP3A4 weakly), reducing diazepam clearance.
What to do
Monitor for excess sedation and consider a lower diazepam dose, particularly in older adults.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Diazepam
Other interactions of Fluoxetine
- Fluoxetine + Isocarboxazid Contraindicated
- Fluoxetine + Mavacamten Contraindicated
- Fluoxetine + Methylene blue Contraindicated
- Fluoxetine + Phenelzine Contraindicated
- Fluoxetine + Pimozide Contraindicated
- Fluoxetine + Rasagiline Contraindicated
Frequently asked questions
Can I take Diazepam with Fluoxetine?
MediHelp rates the interaction as moderate. Diazepam and Fluoxetine can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Fluoxetine and its metabolite norfluoxetine inhibit CYP2C19 and can raise diazepam levels and prolong its half-life. This may increase sedation and psychomotor impairment, and the effect lingers after fluoxetine is stopped.
How serious is the interaction between Diazepam and Fluoxetine?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor for excess sedation and consider a lower diazepam dose, particularly in older adults.
What other medicines interact with Diazepam?
MediHelp also lists interactions of Diazepam with, for example, Calcium / magnesium / potassium / sodium oxybates, Alfentanil, Alprazolam. The full list is on the Diazepam page.
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