Drug interactions
Quetiapine + St john's wort
Severity: Major
Quetiapine and St john's wort: 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
St John's wort induces CYP3A4 and can substantially lower quetiapine concentrations, risking loss of antipsychotic or mood-stabilizing effect. Stopping the herb later may cause quetiapine levels to rise again.
What this interaction means in plain words
Quetiapine and St john's wort 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.
Why it happens
Induction of CYP3A4 (and P-glycoprotein) increases quetiapine clearance.
What to do
Avoid combining. If the herb is stopped, reassess quetiapine dosing and monitor for toxicity as induction wanes.
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 Quetiapine
- Adagrasib + Quetiapine Major
- Amiodarone + Quetiapine Major
- Amisulpride + Quetiapine Major
- Amoxapine + Quetiapine Major
- Anagrelide + Quetiapine Major
- Apalutamide + Quetiapine Major
Frequently asked questions
Can I take Quetiapine with St john's wort?
MediHelp rates the interaction as major. Quetiapine and St john's wort 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. St John's wort induces CYP3A4 and can substantially lower quetiapine concentrations, risking loss of antipsychotic or mood-stabilizing effect. Stopping the herb later may cause quetiapine levels to rise again.
How serious is the interaction between Quetiapine and St john's wort?
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 combining. If the herb is stopped, reassess quetiapine dosing and monitor for toxicity as induction wanes.
What other medicines interact with Quetiapine?
MediHelp also lists interactions of Quetiapine with, for example, Adagrasib, Amiodarone, Amisulpride. The full list is on the Quetiapine page.
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