Overview
Fexofenadine is approved by the U.S. Food and Drug Administration (FDA) to treat chronic idiopathic urticaria, also known as chronic hives. It is used to relieve symptoms such as discolored, raised, itchy areas on the skin that occur regularly for six weeks or more without a known cause. 

Fexofenadine is an antihistamine. It works by blocking the effects of histamine, a chemical in the body that causes allergy symptoms. By targeting peripheral histamine-1 receptors (outside the brain), fexofenadine helps reduce itching and swelling.

How do I take it?
Prescribing information states that fexofenadine is available in multiple forms, including oral tablets, orally disintegrating tablets, and liquid suspension.

For chronic hives, the drug is typically taken once or twice daily with water. It should not be taken with fruit juices such as orange, apple, or grapefruit, as they may reduce absorption. The exact dosage depends on the person's age and formulation. Fexofenadine should be taken exactly as directed by a healthcare provider.

Side effects
Common side effects of fexofenadine include headache, back pain, nausea, tiredness, and cold symptoms such as sore throat or nasal congestion.

Rare but serious side effects may include allergic reactions such as hives, swelling of the face or throat, trouble breathing, and rash. These symptoms require immediate medical attention.

For more information about this treatment, visit:

Fexofenadine — MedlinePlus 

Fexofenadine — Drugs.com