Drug interactions
Montelukast + St john's wort
Severity: Moderate
Montelukast 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 drug-metabolizing enzymes and may lower montelukast concentrations. Reduced efficacy in asthma or allergic rhinitis is theoretically possible.
What this interaction means in plain words
Montelukast 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
Hyperforin in St John's wort activates PXR, inducing CYP3A4 and CYP2C enzymes that metabolize montelukast.
What to do
Advise avoiding St John's wort and monitor asthma control if it is used.
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 Montelukast
- Apalutamide + Montelukast Moderate
- Carbamazepine + Montelukast Moderate
- Deferasirox + Montelukast Moderate
- Enzalutamide + Montelukast Moderate
- Fosphenytoin + Montelukast Moderate
- Gemfibrozil + Montelukast Moderate
Frequently asked questions
Can I take Montelukast with St john's wort?
MediHelp rates the interaction as moderate. Montelukast 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 drug-metabolizing enzymes and may lower montelukast concentrations. Reduced efficacy in asthma or allergic rhinitis is theoretically possible.
How serious is the interaction between Montelukast 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: Advise avoiding St John's wort and monitor asthma control if it is used.
What other medicines interact with Montelukast?
MediHelp also lists interactions of Montelukast with, for example, Apalutamide, Carbamazepine, Deferasirox. The full list is on the Montelukast page.
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