Drug interactions
Pimozide + St john's wort
Severity: Moderate
Pimozide 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 P-glycoprotein, which can lower pimozide concentrations and reduce its efficacy. Stopping St John's wort later may let pimozide levels rise again, creating a risk of QT prolongation.
What this interaction means in plain words
Pimozide 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 (via PXR activation) increases the metabolism of pimozide.
What to do
Avoid the combination where possible. If St John's wort is stopped in a patient stabilized on pimozide, reassess the dose and obtain an ECG because induction wanes over about two weeks.
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 Pimozide
- Adagrasib + Pimozide Contraindicated
- Amiodarone + Pimozide Contraindicated
- Amisulpride + Pimozide Contraindicated
- Amitriptyline + Pimozide Contraindicated
- Amoxapine + Pimozide Contraindicated
- Anagrelide + Pimozide Contraindicated
Frequently asked questions
Can I take Pimozide with St john's wort?
MediHelp rates the interaction as moderate. Pimozide 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 P-glycoprotein, which can lower pimozide concentrations and reduce its efficacy. Stopping St John's wort later may let pimozide levels rise again, creating a risk of QT prolongation.
How serious is the interaction between Pimozide 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: Avoid the combination where possible. If St John's wort is stopped in a patient stabilized on pimozide, reassess the dose and obtain an ECG because induction wanes over about two weeks.
What other medicines interact with Pimozide?
MediHelp also lists interactions of Pimozide with, for example, Adagrasib, Amiodarone, Amisulpride. The full list is on the Pimozide page.
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