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.
Avoid: Adverse interaction—Avoid these supplements when taking this
medication because taking them together may cause undesirable or dangerous results. |
Grapefruit juice
|
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
|
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
Juices
Ingestion of grapefruit juice, orange juice, or apple juice along with fexofenadine decreases blood
levels of the drug.2 3
Alcohol
Selective antihistamines, including fexofenadine, may cause drowsiness or dizziness; however,
it is less likely than with nonselective antihistamines.4 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. Dresser GK, Kim RB, Bailey DG. Effect of grapefruit juice volume on
the reduction of fexofenadine bioavailability: possible role of organic anion transporting
polypeptides. Clin Pharmacol Ther 2005;77:170–7.
4. Threlkeld DS, ed. Respiratory Drugs, Antihistamines. In Facts and
Comparisons Drug Information. St. Louis, MO: Facts and Comparisons, May 1998, 194c.