Drug interactions
Fluoxetine + Fluphenazine
Severity: Major
Fluoxetine and Fluphenazine: 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
Fluoxetine inhibits CYP2D6 and can increase fluphenazine concentrations, raising the risk of extrapyramidal symptoms and other adverse effects. Both drugs may prolong the QT interval, so arrhythmia risk may be additive.
What this interaction means in plain words
Fluoxetine and Fluphenazine 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; Fluphenazine belongs to Central Nervous System.
Why it happens
Fluoxetine inhibits CYP2D6 metabolism of fluphenazine, with additive QT-prolonging pharmacodynamic effects.
What to do
Monitor for extrapyramidal symptoms and consider a lower fluphenazine dose; obtain a baseline ECG and correct potassium and magnesium. Prefer a less interacting antidepressant when feasible.
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 Fluphenazine
- Arsenic trioxide + Fluphenazine Contraindicated
- Dofetilide + Fluphenazine Contraindicated
- Fluphenazine + Ibutilide Contraindicated
- Fluphenazine + Pimozide Contraindicated
- Adagrasib + Fluphenazine Major
- Alfentanil + Fluphenazine Major
Frequently asked questions
Can I take Fluoxetine with Fluphenazine?
MediHelp rates the interaction as major. Fluoxetine and Fluphenazine 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 inhibits CYP2D6 and can increase fluphenazine concentrations, raising the risk of extrapyramidal symptoms and other adverse effects. Both drugs may prolong the QT interval, so arrhythmia risk may be additive.
How serious is the interaction between Fluoxetine and Fluphenazine?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor for extrapyramidal symptoms and consider a lower fluphenazine dose; obtain a baseline ECG and correct potassium and magnesium. Prefer a less interacting antidepressant when feasible.
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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