Drug interactions
Fluoxetine + Isoniazid
Severity: Moderate
Fluoxetine and Isoniazid: 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
Isoniazid's weak MAO inhibition may add to the serotonergic effect of fluoxetine, theoretically increasing serotonin syndrome risk. Clinical cases are rare.
What this interaction means in plain words
Fluoxetine and Isoniazid 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; Isoniazid belongs to Anti Bacterial.
Why it happens
Additive serotonergic effect from weak MAO inhibition and selective serotonin reuptake inhibition.
What to do
Monitor for signs of serotonin toxicity such as tremor, agitation, hyperreflexia and fever. Stop one agent if symptoms develop.
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 Isoniazid
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 Fluoxetine with Isoniazid?
MediHelp rates the interaction as moderate. Fluoxetine and Isoniazid 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. Isoniazid's weak MAO inhibition may add to the serotonergic effect of fluoxetine, theoretically increasing serotonin syndrome risk. Clinical cases are rare.
How serious is the interaction between Fluoxetine and Isoniazid?
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 signs of serotonin toxicity such as tremor, agitation, hyperreflexia and fever. Stop one agent if symptoms develop.
What other medicines interact with Isoniazid?
MediHelp also lists interactions of Isoniazid with, for example, Bacillus calmette-guerin substrain tice, Benzhydrocodone / acetaminophen, Carbamazepine. The full list is on the Isoniazid page.
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