Shop products for Fexofenadine 
Combination drug: Allegra®-D
Fexofenadine is a selective antihistamine used to relieve allergic rhinitis (seasonal allergy) symptoms including sneezing, runny nose, itching, and watery eyes. Fexofenadine is available alone and in a combination product.
Summary of
Interactions with Vitamins, Herbs, and Foods
In some cases, an herb or supplement may appear in more than one category, which may seem
contradictory. For clarification, read the full article for details about the summarized
interactions.
 Check: Other—Before taking any of these supplements
or eating any of these foods with your medication, read this article in full for details. |
St. John's wort |
| Depletion or interference |
None known |
| Side effect reduction/prevention |
None known |
| Supportive interaction |
None known |
| Reduced drug absorption/bioavailability |
None known |
| Adverse interaction |
None known |
An asterisk (*) next to an item in the summary indicates that the interaction is supported only by weak, fragmentary, and/or contradictory scientific evidence.
Interactions with Herbs
St. John's
Wort
In a study of healthy volunteers, administration of 900 mg of St. John's wort one hour prior
to fexofenadine resulted in a significant increase in blood levels of fexofenadine, compared
with the blood levels after taking fexofenadine alone.1 On the other hand,
long-term administration of St. John's wort (300 mg three times per day for two weeks) did not
alter blood levels of fexofenadine. Until more is known, St. John's wort should not be
combined with fexofenadine, except under the supervision of a doctor.
Interactions with Foods and Other Compounds
Food
Ingestion of grapefruit juice, orange juice, or apple juice along with fexofenadine decreases
blood levels of the drug.2
Alcohol
Selective antihistamines, including fexofenadine, may cause drowsiness or dizziness; however,
it is less likely than with nonselective antihistamines.3 Alcohol can intensify
drowsiness and dizziness, increasing the risk of accidental injury.
References
1. Wang Z, Hamman MA, Huang SM, et al. Effect of St John's wort on the pharmacokinetics of fexofenadine. Clin Pharmacol Ther 2002;71:414–20.
2. Dresser GK, Bailey DG, Leake BF, et al. Fruit juices inhibit organic anion transporting polypeptide-mediated drug uptake to decrease the oral availability of fexofenadine. Clin Pharmacol Ther 2002;71:11–20.
3. Threlkeld DS, ed. Respiratory Drugs, Antihistamines. In Facts and Comparisons Drug Information. St. Louis, MO: Facts and Comparisons, May 1998, 194c.
