Drug interactions
Clozapine + Tolterodine
Severity: Major
Clozapine and Tolterodine: major 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
Clozapine has strong antimuscarinic activity, and combining it with tolterodine raises the risk of severe constipation, paralytic ileus, urinary retention, tachycardia and delirium. Clozapine-related gastrointestinal hypomotility can be dangerous.
What this interaction means in plain words
Clozapine and Tolterodine 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.
Clozapine belongs to Central Nervous System; Tolterodine belongs to Genitourinary.
Why it happens
Additive antimuscarinic pharmacodynamic effects.
What to do
Avoid the combination if possible, or monitor bowel function closely and treat constipation early. Consider non-anticholinergic options for overactive bladder, such as a beta-3 agonist.
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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Other interactions of Tolterodine
Other interactions of Clozapine
- Clozapine + Deferiprone Contraindicated
- Clozapine + Irinotecan Contraindicated
- Clozapine + Pimozide Contraindicated
- Clozapine + Thioridazine Contraindicated
- Acalabrutinib + Clozapine Major
- Adagrasib + Clozapine Major
Frequently asked questions
Can I take Clozapine with Tolterodine?
MediHelp rates the interaction as major. Clozapine and Tolterodine 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. Clozapine has strong antimuscarinic activity, and combining it with tolterodine raises the risk of severe constipation, paralytic ileus, urinary retention, tachycardia and delirium. Clozapine-related gastrointestinal hypomotility can be dangerous.
How serious is the interaction between Clozapine and Tolterodine?
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 the combination if possible, or monitor bowel function closely and treat constipation early. Consider non-anticholinergic options for overactive bladder, such as a beta-3 agonist.
What other medicines interact with Tolterodine?
MediHelp also lists interactions of Tolterodine with, for example, Clarithromycin, Cobicistat, Dronedarone. The full list is on the Tolterodine page.
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