Drug interactions
St john's wort + Voriconazole
Severity: Contraindicated
St john's wort and Voriconazole: contraindicated 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 lowers voriconazole concentrations, particularly with long-term use. This may lead to loss of antifungal efficacy and treatment failure.
What this interaction means in plain words
St john's wort and Voriconazole are not normally used together. Taking them at the same time is expected to cause harm or make one of them unsafe, so a different medicine is usually chosen for one of the two.
Why it happens
Induction of CYP3A4, CYP2C19 and P-glycoprotein by hyperforin increases voriconazole clearance.
What to do
Do not use together; stop St John's wort before starting voriconazole. Enzyme induction can persist for about two weeks after discontinuation.
What to ask your pharmacist
- Is there an alternative to one of these two medicines for me?
- If both are essential, who is monitoring me and how often?
- Which symptoms mean I should stop and seek help straight away?
Pro+ members
Unlock the full page
Create an account and start a Pro+ trial to unlock the full management advice for St john's wort and Voriconazole, the additional notes, the evidence detail and the whole-prescription interaction checker.
- Full clinical management advice
- Additional notes
- Evidence detail
- Interaction checker for a whole prescription
Try Pro+ free for 14 days on the web. No card needed.
Other interactions of Voriconazole
- Avanafil + Voriconazole Contraindicated
- Butabarbital + Voriconazole Contraindicated
- Carbamazepine + Voriconazole Contraindicated
- Conivaptan + Voriconazole Contraindicated
- Dihydroergotamine intranasal + Voriconazole Contraindicated
- Dihydroergotamine + Voriconazole Contraindicated
Frequently asked questions
Can I take St john's wort with Voriconazole?
MediHelp rates the interaction as contraindicated. St john's wort and Voriconazole are not normally used together. Taking them at the same time is expected to cause harm or make one of them unsafe, so a different medicine is usually chosen for one of the two. St John's wort lowers voriconazole concentrations, particularly with long-term use. This may lead to loss of antifungal efficacy and treatment failure.
How serious is the interaction between St john's wort and Voriconazole?
MediHelp rates it contraindicated, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Do not use together; stop St John's wort before starting voriconazole. Enzyme induction can persist for about two weeks after discontinuation.
What other medicines interact with Voriconazole?
MediHelp also lists interactions of Voriconazole with, for example, Avanafil, Butabarbital, Carbamazepine. The full list is on the Voriconazole page.
Full monographs, dosing and an interaction checker in the MediHelp app
Open the complete reference, check multi-drug interactions and use dosing tools in the MediHelp app.
