Drug interactions
Dextromethorphan + Pimozide
Severity: Moderate
Dextromethorphan and Pimozide: 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
Pimozide is metabolized by CYP2D6 and CYP3A4, and dextromethorphan competes for CYP2D6, which could raise pimozide levels and QT prolongation risk. Dextromethorphan's serotonergic activity also gives a theoretical risk of serotonin toxicity or neuroleptic malignant syndrome.
What this interaction means in plain words
Dextromethorphan and Pimozide 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.
Dextromethorphan belongs to Respiratory; Pimozide belongs to Central Nervous System.
Why it happens
Possible competition at CYP2D6 plus theoretical additive serotonergic and dopaminergic effects.
What to do
Monitor the ECG QTc interval and for signs of serotonin toxicity or neuroleptic malignant syndrome. Avoid regular dextromethorphan use in patients with QT risk factors.
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 Dextromethorphan
- Dextromethorphan + Isocarboxazid Contraindicated
- Dextromethorphan + Linezolid Contraindicated
- Dextromethorphan + Phenelzine Contraindicated
- Dextromethorphan + Rasagiline Contraindicated
- Dextromethorphan + Safinamide Contraindicated
- Dextromethorphan + Selegiline Contraindicated
Other interactions of Pimozide
- Adagrasib + Pimozide Contraindicated
- Amiodarone + Pimozide Contraindicated
- Amisulpride + Pimozide Contraindicated
- Amitriptyline + Pimozide Contraindicated
- Amoxapine + Pimozide Contraindicated
- Anagrelide + Pimozide Contraindicated
Frequently asked questions
Can I take Dextromethorphan with Pimozide?
MediHelp rates the interaction as moderate. Dextromethorphan and Pimozide 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. Pimozide is metabolized by CYP2D6 and CYP3A4, and dextromethorphan competes for CYP2D6, which could raise pimozide levels and QT prolongation risk. Dextromethorphan's serotonergic activity also gives a theoretical risk of serotonin toxicity or neuroleptic malignant syndrome.
How serious is the interaction between Dextromethorphan and Pimozide?
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 the ECG QTc interval and for signs of serotonin toxicity or neuroleptic malignant syndrome. Avoid regular dextromethorphan use in patients with QT risk factors.
What other medicines interact with Dextromethorphan?
MediHelp also lists interactions of Dextromethorphan with, for example, Isocarboxazid, Linezolid, Phenelzine. The full list is on the Dextromethorphan page.
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