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# Allegra (fexofenadine)
## Overview
Fexofenadine is a second-generation, peripherally selective histamine H1-receptor antagonist. It is non-sedating due to minimal brain penetration.
## Primary Indications
- Seasonal allergic rhinitis (SAR)
- Chronic idiopathic urticaria (CIU)
## Adult Dosing
- **SAR/CIU**: 60 mg twice daily OR 180 mg once daily
## Pediatric Dosing
- **6 months to <2 years** (SAR/CIU): 15 mg twice daily
- **2 to 11 years** (SAR/CIU): 30 mg twice daily
- **12 years and older**: Same as adult
> Note: Dosing may vary by formulation (tablet vs. suspension). Confirm local protocol.
## Dose Adjustments
- **Renal impairment (CrCl < 80 mL/min)**: Start at 60 mg once daily for SAR; 30 mg once daily for CIU in children 6 months–11 years.
- **Hepatic impairment**: No dose adjustment needed.
## Contraindications
- Hypersensitivity to fexofenadine or any component
## Adverse Effects
- Most common: headache, drowsiness (less than first-gen antihistamines), dizziness, nausea
- Serious (rare): hypersensitivity reactions
## Key Drug Interactions
- **Antacids (aluminum/magnesium)**: Reduce fexofenadine absorption; separate by at least 2 hours
- **Fruit juices (grapefruit, orange, apple)**: Can decrease absorption; avoid concurrent administration
- **Erythromycin/ketoconazole**: Increase fexofenadine levels but no dose adjustment needed; monitor for increased side effects
## Monitoring
- Symptom relief; monitor renal function in elderly or with impairment
## Clinical Pearls
- Onset within 1 hour, duration up to 24 hours
- Does not prolong QTc at therapeutic doses (distinct advantage over some other antihistamines)
- Take with water only (not fruit juice) for optimal absorption
- Use the lowest effective dose in renal impairment
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*Educational disclaimer: This information is for educational purposes only. Always verify current prescribing information from a reliable drug reference or the manufacturer's label before making clinical decisions.*
