Drug interactions
Fluoxetine + Fluvoxamine
Severity: Major
Fluoxetine and Fluvoxamine: 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
Both drugs are SSRIs and together can cause excessive serotonergic stimulation, including serotonin syndrome. Fluvoxamine also inhibits CYP2C19 and CYP2D6 and fluoxetine inhibits CYP2D6, which can increase levels of either drug.
What this interaction means in plain words
Fluoxetine and Fluvoxamine 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.
Fluoxetine belongs to Central Nervous System; Fluvoxamine belongs to Central Nervous System.
Why it happens
Additive serotonin reuptake inhibition with mutual cytochrome P450 inhibition.
What to do
Avoid using the two together; use a single SSRI and cross-taper when switching, allowing for fluoxetine's long half-life. Monitor for agitation, tremor, hyperreflexia and fever if overlap occurs.
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 Fluvoxamine
- Agomelatine + Fluvoxamine Contraindicated
- Alosetron + Fluvoxamine Contraindicated
- Fezolinetant + Fluvoxamine Contraindicated
- Fluvoxamine + Isocarboxazid Contraindicated
- Fluvoxamine + Mavacamten Contraindicated
- Fluvoxamine + Methylene blue Contraindicated
Frequently asked questions
Can I take Fluoxetine with Fluvoxamine?
MediHelp rates the interaction as major. Fluoxetine and Fluvoxamine 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. Both drugs are SSRIs and together can cause excessive serotonergic stimulation, including serotonin syndrome. Fluvoxamine also inhibits CYP2C19 and CYP2D6 and fluoxetine inhibits CYP2D6, which can increase levels of either drug.
How serious is the interaction between Fluoxetine and Fluvoxamine?
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 the two together; use a single SSRI and cross-taper when switching, allowing for fluoxetine's long half-life. Monitor for agitation, tremor, hyperreflexia and fever if overlap occurs.
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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