Does Allegra (fexofenadine) cause side effects?

Allegra (fexofenadine) is an oral, "second generation" antihistamine used to treat seasonal allergies in patients 2 years of age and older and chronic urticaria (hives, itching) in patients 6 months of age and older. 

Histamine is a chemical that is responsible for many of the signs and symptoms of allergic reactions, for example, swelling of the lining of the nose, sneezing, and itchy eyes. Histamine is released from histamine-storing cells (mast cells) and then attaches to other cells that have receptors for histamine. 

The attachment of the histamine to the receptors causes the cells to be "activated," releasing other chemicals that produce the effects that we associate with allergy (for example, sneezing). Allegra blocks one type of receptor for histamine (the H1 receptor) and thus prevents activation of H1 receptor-containing cells by histamine. 

Unlike the first-generation antihistamines, Allegra and other second-generation antihistamines do not readily enter the brain from the blood. Therefore, they cause less drowsiness and are called non-sedating antihistamines. 

Common side effects of Allegra include

Other important side effects of Allegra include

Drug interactions of Allegra include aluminum-containing antacids (for example, Maalox), which reduce the absorption of Allegra when administered 15 minutes apart.

  • Therefore, aluminum-containing antacids and Allegra should not be administered together. Fruit juices (apple, orange, grapefruit) may reduce the absorption of Allegra.
  • Allegra should only be administered with water. 

Allegra has not been adequately studied in pregnant women. Allegra has not been adequately studied in women who are breastfeeding. Consult your doctor before breastfeeding.

What are the important side effects of Allegra (fexofenadine)?

The most common side effects of fexofenadine are:

Other important side effects include:

Allegra (fexofenadine) side effects list for healthcare professionals

No information provided.

What drugs interact with Allegra (fexofenadine)?

No information provided.

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Medically Reviewed on 11/18/2020
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Professional side effects and drug interactions sections courtesy of the U.S. Food and Drug Administration.