Drug interactions
Citalopram + Fluoxetine
Severity: Major
Citalopram and Fluoxetine: major interaction.
Last updated Sources: US FDA label
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
Combining two SSRIs increases the risk of serotonin syndrome without clear added benefit. Fluoxetine also inhibits CYP2D6 and CYP2C19 and can raise citalopram levels, which adds to the dose-dependent QT prolongation of citalopram.
What this interaction means in plain words
Citalopram and Fluoxetine can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Citalopram belongs to Central Nervous System; Fluoxetine belongs to Central Nervous System.
Why it happens
Additive serotonergic effects and fluoxetine-mediated inhibition of citalopram metabolism, enhancing QT prolongation.
What to do
Avoid using two SSRIs together and choose a single agent at an optimized dose. If a cross-over is needed, taper gradually, allow for fluoxetine's long half-life and monitor for serotonin toxicity and QTc.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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References
Other interactions of Fluoxetine
- Fluoxetine + Isocarboxazid Contraindicated
- Fluoxetine + Mavacamten Contraindicated
- Fluoxetine + Methylene blue Contraindicated
- Fluoxetine + Phenelzine Contraindicated
- Fluoxetine + Pimozide Contraindicated
- Fluoxetine + Rasagiline Contraindicated
Other interactions of Citalopram
- Cisapride + Citalopram Contraindicated
- Citalopram + Dronedarone Contraindicated
- Citalopram + Escitalopram Contraindicated
- Citalopram + Isocarboxazid Contraindicated
- Citalopram + Methylene blue Contraindicated
- Citalopram + Phenelzine Contraindicated
Frequently asked questions
Can I take Citalopram with Fluoxetine?
MediHelp rates the interaction as major. Citalopram and Fluoxetine can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Combining two SSRIs increases the risk of serotonin syndrome without clear added benefit. Fluoxetine also inhibits CYP2D6 and CYP2C19 and can raise citalopram levels, which adds to the dose-dependent QT prolongation of citalopram.
How serious is the interaction between Citalopram and Fluoxetine?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid using two SSRIs together and choose a single agent at an optimized dose. If a cross-over is needed, taper gradually, allow for fluoxetine's long half-life and monitor for serotonin toxicity and QTc.
What other medicines interact with Fluoxetine?
MediHelp also lists interactions of Fluoxetine with, for example, Isocarboxazid, Mavacamten, Methylene blue. The full list is on the Fluoxetine page.
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