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# Allegra (fexofenadine)
## Overview
Fexofenadine is a second-generation, selective H1-receptor antagonist. It lacks the significant sedative effects associated with first-generation antihistamines because it does not readily cross the blood-brain barrier.
## Primary Indications
* Seasonal Allergic Rhinitis (SAR)
* Chronic Idiopathic Urticaria (CIU)
## Adult Dosing
* **SAR:** 60 mg orally twice daily OR 180 mg orally once daily.
* **CIU:** 60 mg orally twice daily.
* **Maximum:** 180 mg per day.
## Pediatric Dosing
* **Ages 6 to 11 years:** 30 mg orally twice daily.
* **Ages 12 years and older:** Same as adult dosing (60 mg BID or 180 mg daily).
* **Note:** Oral suspension is available for younger children; verify specific concentration as labeling may vary.
## Dose Adjustments
* **Renal Impairment:** Adjust dose for creatinine clearance (CrCl) < 80 mL/min.
* **Adults/Children ≥ 12 years:** Start with 60 mg once daily.
* **Children 6 to 11 years:** Start with 30 mg once daily.
* **Hepatic Impairment:** No specific dosage adjustment is recommended, though clinical caution is advised.
## Contraindications
* Hypersensitivity to fexofenadine or any component of the formulation.
## Adverse Effects
* **Common:** Headache, nausea, dizziness, fatigue, and viral infections (upper respiratory tract).
* **Rare:** Hypersensitivity reactions (urticaria, angioedema, chest tightness, dyspnea).
## Key Drug Interactions
* **Antacids (Aluminum/Magnesium):** May decrease fexofenadine absorption. Separate administration by at least 2 hours.
* **Fruit Juices:** Grapefruit, orange, and apple juice may significantly decrease fexofenadine systemic exposure (AUC). Avoid concurrent intake.
* **Erythromycin/Ketoconazole:** May increase fexofenadine plasma concentrations; however, this is rarely clinically significant due to the drug's safety profile.
## Monitoring
* Monitor for symptomatic relief of allergic rhinitis or urticaria.
* Monitor for signs of adverse effects if used in patients with impaired renal function.
## Clinical Pearls
* **Non-Sedating:** Generally considered non-sedating, making it a preferred choice for patients who require high mental alertness.
* **Fast Onset:** Typically provides relief within 1 to 2 hours of administration.
* **Dosing Optimization:** The 180 mg once-daily formulation is preferred for adherence.
* **Pregnancy/Lactation:** Fexofenadine is generally considered compatible, but consult current institutional guidelines or lactation databases (e.g., LactMed) for the most recent clinical consensus.
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*Disclaimer: This information is for educational purposes and does not replace medical advice. Always verify current prescribing information, institutional protocols, and patient-specific factors with a healthcare provider before administration.*
