What is the recommended dosage and treatment plan for fexofenadine (Allegra) in allergic reactions?

Fexofenadine (Allegra) Dosage and Treatment Plan for Allergic Reactions

For allergic reactions, fexofenadine is recommended at 60 mg twice daily or 180 mg once daily for adults and children 12 years and older, and 30 mg twice daily for children 6-11 years old. 1

Adult Dosing Recommendations

Standard Dosing

• Seasonal Allergic Rhinitis:
  • 60 mg twice daily OR 180 mg once daily with water 1
  • Onset of relief occurs within 2 hours of administration 2
  • Duration of action is long enough for once-daily dosing 2

Chronic Idiopathic Urticaria:

• 60 mg twice daily OR 180 mg once daily with water 1
• Clinical trials have shown effectiveness for up to 6 weeks of treatment 2

Special Populations:

• Patients with decreased renal function: 60 mg once daily as starting dose 1

Pediatric Dosing

Children 12 years and older:

• Same as adult dosing: 60 mg twice daily OR 180 mg once daily 1

Children 6-11 years:

• 30 mg twice daily with water 1
• For decreased renal function: 30 mg once daily as starting dose 1

Clinical Efficacy and Safety

Fexofenadine is particularly effective for:

• Sneezing
• Rhinorrhea
• Itchy nose, palate, or throat
• Itchy, watery, red eyes 2

Fexofenadine offers several advantages over other antihistamines:

1. Non-sedating profile: 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

2. Cardiac safety: Does not inhibit cardiac K+ channels and is not associated with QT interval prolongation, even when given with erythromycin or ketoconazole 2, 3

3. Favorable side effect profile: The incidence of adverse events is similar to placebo in clinical trials, with headache being the most commonly reported adverse event 2, 3

4. No cognitive/psychomotor impairment: Does not impair driving ability or psychomotor performance 3

Comparison with Other Antihistamines

• Fexofenadine is as effective as loratadine 10 mg once daily and cetirizine 10 mg once daily in reducing overall symptoms of seasonal allergic rhinitis 2, 4

• The combined incidence of drowsiness or fatigue is significantly lower with fexofenadine (4%) compared to cetirizine (9%) 4

• According to the Joint Task Force on Practice Parameters, fexofenadine, loratadine, and desloratadine do not cause sedation at recommended doses, while cetirizine and intranasal azelastine may cause sedation 5

Treatment Algorithm for Allergic Reactions

1. Mild allergic reactions (flushing, urticaria, mild angioedema):

   • Fexofenadine as first-line H1 antihistamine due to non-sedating properties 5
   • Consider adding H2 antihistamine (ranitidine) for enhanced efficacy 5

2. Severe allergic reactions/anaphylaxis:

   • Epinephrine is FIRST-LINE treatment, not antihistamines 5
   • Fexofenadine should only be used as adjunctive therapy after epinephrine 5

3. For ongoing management after acute reaction:

   • Continue fexofenadine at recommended doses for 2-3 days 5

Important Considerations

• Fexofenadine works better as prophylactic than acute treatment for allergic symptoms 5
• For nasal congestion, fexofenadine produces only small improvements; consider adding pseudoephedrine for better relief of this symptom 2
• Elderly patients should preferentially receive second-generation antihistamines like fexofenadine over first-generation antihistamines due to reduced risk of cognitive impairment 5
• Monitor for headache, which is the most common side effect but occurs at similar rates to placebo 2, 6