Drug interactions
Dextromethorphan + Thioridazine
Severity: Moderate
Dextromethorphan and Thioridazine: 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
Thioridazine inhibits CYP2D6 and can increase dextromethorphan exposure, with additive sedation. Thioridazine itself is a CYP2D6 substrate with QT-prolonging risk, so combined use adds complexity in vulnerable patients.
What this interaction means in plain words
Dextromethorphan and Thioridazine 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; Thioridazine belongs to Central Nervous System.
Why it happens
CYP2D6 inhibition by thioridazine raises dextromethorphan levels, with additive CNS depression.
What to do
Avoid unnecessary dextromethorphan use; if needed, use the lowest dose and monitor for sedation, confusion and QT-related symptoms.
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 Thioridazine
- Abiraterone + Thioridazine Contraindicated
- Adagrasib + Thioridazine Contraindicated
- Amiodarone + Thioridazine Contraindicated
- Amisulpride + Thioridazine Contraindicated
- Amitriptyline + Thioridazine Contraindicated
- Amoxapine + Thioridazine Contraindicated
Frequently asked questions
Can I take Dextromethorphan with Thioridazine?
MediHelp rates the interaction as moderate. Dextromethorphan and Thioridazine 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. Thioridazine inhibits CYP2D6 and can increase dextromethorphan exposure, with additive sedation. Thioridazine itself is a CYP2D6 substrate with QT-prolonging risk, so combined use adds complexity in vulnerable patients.
How serious is the interaction between Dextromethorphan and Thioridazine?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid unnecessary dextromethorphan use; if needed, use the lowest dose and monitor for sedation, confusion and QT-related symptoms.
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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