Drug interactions
Haloperidol + Tolterodine
Severity: Moderate
Haloperidol and Tolterodine: 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
Both drugs can prolong the QT interval, and tolterodine adds antimuscarinic effects to those of haloperidol. Patients may experience dry mouth, constipation, urinary retention, confusion and a higher risk of arrhythmia. Haloperidol also inhibits CYP2D6 to a degree, which may raise tolterodine levels.
What this interaction means in plain words
Haloperidol and Tolterodine 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.
Haloperidol belongs to Central Nervous System; Tolterodine belongs to Genitourinary.
Why it happens
Additive QT prolongation and antimuscarinic effects, with possible CYP2D6 inhibition.
What to do
Check an ECG when starting the combination in patients with QT risk factors, and correct potassium and magnesium. Monitor for anticholinergic effects and use the lowest effective doses.
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 Tolterodine
Other interactions of Haloperidol
- Dofetilide + Haloperidol Contraindicated
- Dronedarone + Haloperidol Contraindicated
- Haloperidol + Ibutilide Contraindicated
- Haloperidol + Levoketoconazole Contraindicated
- Haloperidol + Panobinostat Contraindicated
- Haloperidol + Pimozide Contraindicated
Frequently asked questions
Can I take Haloperidol with Tolterodine?
MediHelp rates the interaction as moderate. Haloperidol and Tolterodine 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. Both drugs can prolong the QT interval, and tolterodine adds antimuscarinic effects to those of haloperidol. Patients may experience dry mouth, constipation, urinary retention, confusion and a higher risk of arrhythmia. Haloperidol also inhibits CYP2D6 to a degree, which may raise tolterodine levels.
How serious is the interaction between Haloperidol and Tolterodine?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Check an ECG when starting the combination in patients with QT risk factors, and correct potassium and magnesium. Monitor for anticholinergic effects and use the lowest effective doses.
What other medicines interact with Tolterodine?
MediHelp also lists interactions of Tolterodine with, for example, Clarithromycin, Clozapine, Cobicistat. The full list is on the Tolterodine page.
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