Fexofenadine - Precautions | Side Effects

This article was medically reviewed by M.Pharm, Marko Tanaskovic on August 12, 2018. To read more about an author, click here.

Fexofenadine belongs to a group of medicines called H1 antihistamines that competitively block histamine receptors and thereby prevent the histamine action, but does not affect histamine release. Fexofenadine is used to relieve symptoms of seasonal allergies (sneezing, itching and others).

It is used to relieve symptoms of following conditions:

  • Seasonal allergic rhinitis
  • Chronic idiopathic urticaria


Fexofenadine is rapidly absorbed from the gastrointestinal tract after oral administration. The maximum plasma concentrations reaching a peak 2 to 3 hours after oral administration. This medicine is widely distributed throughout the body. The medicine binds to plasma proteins (binding rate 60 - 70 %). The largest part of Fexofenadine is metabolized by intestinal microflora, but a small part, up to 1.5 %, is metabolized by the liver. Fexofenadine is excreted unchanged through the feces (80 %) and through the urine (11 %). Mean half-life of this medicine is approximately 14 hours.


This medicine should be avoided:

  • In patients with renal impairment
  • In patients allergic to fexofenadine or other similar medications

This medicine should be taken on an empty stomach at least one hour before meal. It should be taken only if recommended by doctor.

Side effects

Fexofenadine may cause following side effects:

  • Muscle pain
  • Back pain
  • Headache
  • Menstrual cramps
  • Drowsiness
  • Nausea
  • Diarrhea

Contact your doctor immediately if you are experiencing any side effects.

Use with other medicines (Interactions)

It should be avoided in combination with following medications:

  • Medications used to treat fungal infections, such as: ketoconazole, itraconazole, fluconazole and others. Concomitant use of these medicines with Fexofenadine may increase concentrations of Fexofenadine in the blood, increasing risk of side effects.
  • Antibiotics, such as: erythromycin.
  • Aluminum and magnesium antacids. These medicines decrease absorption of Fexofenadine which result in decreased Fexofenadine efficacy. Therefore, it is recommended to take antacids 4 hours before or 4 hours after taking Fexofenadine.

Pregnancy and breastfeeding

Fexofenadine can be used during pregnancy only if the the benefits to the mother outweighs the potential risk to the fetus.

It is not known whether this medicine is excreted into breast milk. Avoid breastfeeding while taking this medicine.

Brand names: Allegra, Allegra Allergy, Allegra ODT, Aller-Ease, Children's Allegra Allergy, Children's Allegra ODT and Allergy Relief.

Information on this website are provided for educational purposes only and are not intended for medical advice, diagnosis or treatment.

If you have any concerns or questions about your health, you should always consult with a physician or other health-care professional.

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