Drug interactions
St john's wort + Terbinafine
Severity: Moderate
St john's wort and Terbinafine: 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 drug-metabolizing enzymes and may reduce terbinafine concentrations. This could lead to reduced antifungal efficacy.
What this interaction means in plain words
St john's wort and Terbinafine 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
St John's wort induces CYP3A4 and other enzymes (and P-gp), increasing terbinafine clearance.
What to do
Advise avoiding St John's wort during terbinafine therapy; if continued, monitor clinical response and consider alternative therapy if response is inadequate.
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 Terbinafine
- Terbinafine + Thioridazine Contraindicated
- Desipramine + Terbinafine Major
- Eliglustat + Terbinafine Major
- Flecainide + Terbinafine Major
- Imipramine + Terbinafine Major
- Maprotiline + Terbinafine Major
Frequently asked questions
Can I take St john's wort with Terbinafine?
MediHelp rates the interaction as moderate. St john's wort and Terbinafine 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 drug-metabolizing enzymes and may reduce terbinafine concentrations. This could lead to reduced antifungal efficacy.
How serious is the interaction between St john's wort and Terbinafine?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Advise avoiding St John's wort during terbinafine therapy; if continued, monitor clinical response and consider alternative therapy if response is inadequate.
What other medicines interact with Terbinafine?
MediHelp also lists interactions of Terbinafine with, for example, Thioridazine, Desipramine, Eliglustat. The full list is on the Terbinafine page.
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