Drug interactions
Fexofenadine + St john's wort
Severity: Minor
Fexofenadine and St john's wort: minor 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 P-glycoprotein and may lower fexofenadine exposure with long-term use. Reduced antihistamine effect is possible but rarely significant.
What this interaction means in plain words
Fexofenadine and St john's wort have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Why it happens
Induction of intestinal P-gp efflux by St John's wort constituents, reducing fexofenadine absorption.
What to do
No routine action is needed; if allergy control worsens, review the herbal supplement or switch antihistamine.
What to ask your pharmacist
- Is there anything I should notice while taking both?
- Do I need to tell my doctor at the next visit?
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Other interactions of Fexofenadine
- Danicopan + Fexofenadine Moderate
- Erdafitinib + Fexofenadine Moderate
- Fexofenadine + Glecaprevir / pibrentasvir Moderate
- Fexofenadine + Grapefruit Moderate
- Fexofenadine + Juice Moderate
- Acrivastine + Fexofenadine Minor
Frequently asked questions
Can I take Fexofenadine with St john's wort?
MediHelp rates the interaction as minor. Fexofenadine and St john's wort have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. St John's wort induces P-glycoprotein and may lower fexofenadine exposure with long-term use. Reduced antihistamine effect is possible but rarely significant.
How serious is the interaction between Fexofenadine and St john's wort?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: No routine action is needed; if allergy control worsens, review the herbal supplement or switch antihistamine.
What other medicines interact with Fexofenadine?
MediHelp also lists interactions of Fexofenadine with, for example, Danicopan, Erdafitinib, Glecaprevir / pibrentasvir. The full list is on the Fexofenadine page.
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