Recommended Dosage and Usage of Fexofenadine (Allegra) for Treating Allergic Reactions
For allergic rhinitis in adults and children 12 years and older, the recommended dosage of fexofenadine is 60 mg twice daily or 180 mg once daily with water. 1
Dosage Recommendations by Age Group and Condition
Adults and Children 12 Years and Older:
- For seasonal allergic rhinitis: 60 mg twice daily or 180 mg once daily 1
- For chronic idiopathic urticaria: 60 mg twice daily or 180 mg once daily 1
- Fexofenadine is rapidly absorbed with onset of relief within 2 hours and has a long duration of action, making it suitable for once-daily administration 2
Children 6 to 11 Years:
- For seasonal allergic rhinitis: 30 mg twice daily 1
- For chronic idiopathic urticaria: 30 mg twice daily 1
Patients with Decreased Renal Function:
- Adults and children 12 years and older: Starting dose of 60 mg once daily 1
- Children 6 to 11 years: Starting dose of 30 mg once daily 1
Advantages of Fexofenadine
- Fexofenadine is a second-generation antihistamine that does not cause sedation at recommended doses 3
- Unlike first-generation antihistamines, fexofenadine does not cross the blood-brain barrier and is free of sedative effects even at dosages up to 240 mg/day 2
- Fexofenadine has no tendency to cause performance impairment, which is a significant advantage over first-generation antihistamines 3
- The safety profile of fexofenadine is similar to placebo, with headache being the most commonly reported adverse event 4
- Fexofenadine does not inhibit cardiac K+ channels and is not associated with QT interval prolongation, making it safer than some other antihistamines 2
Clinical Efficacy
- Fexofenadine is effective in relieving symptoms of sneezing, rhinorrhea, itchy nose/palate/throat, and itchy/watery/red eyes in patients with seasonal allergic rhinitis 2
- Clinical trials have shown fexofenadine to be as effective as loratadine 10 mg once daily and cetirizine 10 mg once daily in reducing overall symptoms of seasonal allergic rhinitis 2, 5
- For chronic idiopathic urticaria, fexofenadine 180 mg once daily effectively reduces symptoms for up to 6 weeks 2
- In a study of Thai patients with chronic idiopathic urticaria, 95% reported improvement with fexofenadine 60 mg twice daily 6
Important Considerations and Caveats
- Second-generation antihistamines like fexofenadine are generally preferred over first-generation antihistamines due to their favorable safety profile 3
- First-generation antihistamines can cause significant sedation, performance impairment, and anticholinergic effects that can be dangerous, particularly in elderly patients 3
- Fexofenadine is well tolerated in clinical trials with an adverse event profile similar to placebo 4
- Fexofenadine has been shown to maintain efficacy for the entire 24-hour dosing interval when administered once daily 5
- For patients with excessive nasal congestion, fexofenadine has small improvements in nasal congestion that can be further enhanced when combined with pseudoephedrine 2
Pharmacokinetics
- Fexofenadine is rapidly absorbed, reaching peak concentrations in 0.83 to 1.33 hours 7
- The mean area under the plasma concentration-time curve is approximately proportional to dose 7
- Oral clearance, renal clearance, and cumulative percent of drug excreted in urine are similar after single and multiple doses 7
- Fexofenadine has been well tolerated at oral doses up to 11 times the recommended therapeutic dose 7
By following these dosage recommendations and understanding the advantages of fexofenadine over other antihistamines, healthcare providers can effectively treat allergic reactions while minimizing adverse effects.