Drug interactions
St john's wort + Tolterodine
Severity: Moderate
St john's wort 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
St John's wort induces CYP3A4 and may lower tolterodine concentrations, potentially reducing control of overactive bladder symptoms. The effect is likely modest and varies between preparations.
What this interaction means in plain words
St john's wort 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.
Why it happens
Induction of CYP3A4 by hyperforin increases tolterodine metabolism.
What to do
Ask patients about herbal use and monitor for loss of efficacy; stop St John's wort or adjust tolterodine if symptoms worsen.
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
Frequently asked questions
Can I take St john's wort with Tolterodine?
MediHelp rates the interaction as moderate. St john's wort 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. St John's wort induces CYP3A4 and may lower tolterodine concentrations, potentially reducing control of overactive bladder symptoms. The effect is likely modest and varies between preparations.
How serious is the interaction between St john's wort 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: Ask patients about herbal use and monitor for loss of efficacy; stop St John's wort or adjust tolterodine if symptoms worsen.
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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