Drug interactions
Exemestane + St john's wort
Severity: Major
Exemestane and St john's wort: major interaction.
Last updated Sources: US FDA label
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 may lower exemestane exposure, risking reduced antiestrogenic effect. Herbal product potency varies.
What this interaction means in plain words
Exemestane 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
Hyperforin-mediated induction of CYP3A4 (via PXR) increases exemestane metabolism.
What to do
Advise patients to avoid St John's wort; if unavoidable, use exemestane 50 mg daily after a meal.
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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References
Other interactions of Exemestane
Frequently asked questions
Can I take Exemestane with St john's wort?
MediHelp rates the interaction as major. Exemestane 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 may lower exemestane exposure, risking reduced antiestrogenic effect. Herbal product potency varies.
How serious is the interaction between Exemestane 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: Advise patients to avoid St John's wort; if unavoidable, use exemestane 50 mg daily after a meal.
What other medicines interact with Exemestane?
MediHelp also lists interactions of Exemestane with, for example, Bazedoxifene-conjugated estrogens, Desogestrel-ethinyl estradiol, Estradiol. The full list is on the Exemestane page.
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