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# Fexofenadine (Allegra)
## Overview
Fexofenadine is a second-generation H1 antihistamine used for the symptomatic relief of allergic conditions. It is a metabolite of terfenadine and does not possess the cardiac risk associated with its parent compound.
## Primary Indications
* Seasonal allergic rhinitis (hay fever)
* Perennial allergic rhinitis
* Chronic idiopathic urticaria (hives)
## Adult Dosing
* **Seasonal/Perennial Allergic Rhinitis:** 60 mg twice daily or 180 mg once daily.
* **Chronic Idiopathic Urticaria:** 60 mg twice daily.
## Pediatric Dosing
* **6 months to 11 years (Seasonal/Perennial Allergic Rhinitis and Chronic Idiopathic Urticaria):**
* 30 mg twice daily.
* **2 years to 11 years (Seasonal/Perennial Allergic Rhinitis and Chronic Idiopathic Urticaria):**
* 60 mg once daily OR 30 mg twice daily.
* **12 years and older:** Same as adult dosing.
Dosing in infants under 6 months is not established.
## Dose Adjustments
No dose adjustments are generally needed for renal or hepatic impairment due to minimal hepatic metabolism and renal excretion of active drug.
## Contraindications
Hypersensitivity to fexofenadine or any component of the formulation.
## Adverse Effects
Common: Headache, dizziness, nausea, fatigue.
Less Common: Somnolence, xerostomia.
## Key Drug Interactions
* **Antacids containing aluminum and magnesium:** May decrease fexofenadine absorption. Separate administration by at least 2 hours.
* **Fruit juices (e.g., grapefruit, orange):** May decrease fexofenadine absorption. Separate administration may be beneficial.
## Monitoring
* Monitor for symptom relief.
* Assess for potential adverse effects, particularly somnolence, though less common with fexofenadine compared to first-generation antihistamines.
## Clinical Pearls
* Fexofenadine offers a good balance of efficacy and an improved safety profile (lack of QTc prolongation) compared to older antihistamines.
* Dosing frequency can be once or twice daily depending on the indication and patient response.
* The 180 mg dose for allergic rhinitis provides once-daily dosing convenience.
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*This information is intended for healthcare professionals and does not replace the need to consult the most current prescribing information and relevant clinical guidelines.*
