Drug interactions
Oxybutynin + St john's wort
Severity: Moderate
Oxybutynin and St john's wort: 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 oxybutynin concentrations, potentially reducing efficacy. The effect is likely greater with oral immediate-release dosing.
What this interaction means in plain words
Oxybutynin and St john's wort 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 increasing oxybutynin metabolism.
What to do
Monitor for loss of bladder symptom control and consider avoiding St John's wort or adjusting the oxybutynin dose.
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 Oxybutynin
Frequently asked questions
Can I take Oxybutynin with St john's wort?
MediHelp rates the interaction as moderate. Oxybutynin and St john's wort 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 oxybutynin concentrations, potentially reducing efficacy. The effect is likely greater with oral immediate-release dosing.
How serious is the interaction between Oxybutynin and St john's wort?
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 for loss of bladder symptom control and consider avoiding St John's wort or adjusting the oxybutynin dose.
What other medicines interact with Oxybutynin?
MediHelp also lists interactions of Oxybutynin with, for example, Bethanechol, Clozapine, Potassium chloride. The full list is on the Oxybutynin page.
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