Drug interactions
Fluoxetine + Mirtazapine
Severity: Moderate
Fluoxetine and Mirtazapine: 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
Both drugs have some QT-prolonging potential, and combined use may add to arrhythmia risk, mainly at high doses or with other risk factors. The combination also carries a serotonin syndrome risk, though it is commonly used deliberately in resistant depression.
What this interaction means in plain words
Fluoxetine and Mirtazapine 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 belongs to Central Nervous System; Mirtazapine belongs to Central Nervous System.
Why it happens
Additive QT prolongation and additive serotonergic effects.
What to do
Check ECG in patients with cardiac disease or other QT-prolonging drugs, and keep electrolytes normal. Monitor for signs of serotonin toxicity after starting or increasing doses.
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?
Pro+ members
Unlock the full page
Create an account and start a Pro+ trial to unlock the full management advice for Fluoxetine and Mirtazapine, the additional notes, the evidence detail and the whole-prescription interaction checker.
- Full clinical management advice
- Additional notes
- Evidence detail
- Interaction checker for a whole prescription
Try Pro+ free for 7 days on the web. No card needed.
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 Mirtazapine
- Isocarboxazid + Mirtazapine Contraindicated
- Mirtazapine + Phenelzine Contraindicated
- Mirtazapine + Pimozide Contraindicated
- Mirtazapine + Procarbazine Contraindicated
- Mirtazapine + Rasagiline Contraindicated
- Mirtazapine + Selegiline Contraindicated
Frequently asked questions
Can I take Fluoxetine with Mirtazapine?
MediHelp rates the interaction as moderate. Fluoxetine and Mirtazapine 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. Both drugs have some QT-prolonging potential, and combined use may add to arrhythmia risk, mainly at high doses or with other risk factors. The combination also carries a serotonin syndrome risk, though it is commonly used deliberately in resistant depression.
How serious is the interaction between Fluoxetine and Mirtazapine?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Check ECG in patients with cardiac disease or other QT-prolonging drugs, and keep electrolytes normal. Monitor for signs of serotonin toxicity after starting or increasing doses.
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.
Full monographs, dosing and an interaction checker in the MediHelp app
Open the complete reference, check multi-drug interactions and use dosing tools in the MediHelp app.
