Drug interactions
St john's wort + Tolvaptan
Severity: Major
St john's wort and Tolvaptan: 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 P-gp, lowering tolvaptan levels and risking loss of effect. Labeling advises avoiding the combination.
What this interaction means in plain words
St john's wort and Tolvaptan 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-gp increases tolvaptan clearance.
What to do
Avoid St John's wort in patients on tolvaptan. If it is stopped, monitor sodium as induction wanes and reassess the tolvaptan dose.
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 Tolvaptan
- Atazanavir + Tolvaptan Contraindicated
- Ceritinib + Tolvaptan Contraindicated
- Cobicistat + Tolvaptan Contraindicated
- Conivaptan + Tolvaptan Contraindicated
- Darunavir + Tolvaptan Contraindicated
- Idelalisib + Tolvaptan Contraindicated
Frequently asked questions
Can I take St john's wort with Tolvaptan?
MediHelp rates the interaction as major. St john's wort and Tolvaptan 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 P-gp, lowering tolvaptan levels and risking loss of effect. Labeling advises avoiding the combination.
How serious is the interaction between St john's wort and Tolvaptan?
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 St John's wort in patients on tolvaptan. If it is stopped, monitor sodium as induction wanes and reassess the tolvaptan dose.
What other medicines interact with Tolvaptan?
MediHelp also lists interactions of Tolvaptan with, for example, Atazanavir, Ceritinib, Cobicistat. The full list is on the Tolvaptan page.
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