What is the recommended dose of cetirizine (antihistamine) for a child weighing 46 pounds?

Cetirizine Dosage for a 46-Pound Child

For a child weighing 46 pounds (approximately 21 kg), the recommended dose of cetirizine is 5 mg once daily.

Dosage Recommendations

• For children weighing 46 pounds (>20 kg), the appropriate cetirizine dose is 5 mg once daily 1
• The American Academy of Allergy, Asthma, and Immunology specifically recommends 5 mg once daily for a child weighing 45 pounds, which is very close to the weight in question 1
• For pediatric patients, cetirizine dosing is primarily based on weight rather than age, ensuring appropriate therapeutic levels while minimizing side effects 2

Administration Considerations

• If drowsiness occurs (which happens in approximately 13.7% of children compared to 6.3% with placebo), consider administering the dose in the evening 1
• Cetirizine has a rapid onset of action, with significant clinical effects occurring within 20 minutes of administration 3
• The antihistamine effect of cetirizine persists for 24 hours, making once-daily dosing appropriate 3
• No tolerance to the therapeutic effect develops even after one month of daily treatment 3

Safety Profile

• Cetirizine is generally well-tolerated in children with a safety profile comparable to placebo 1
• Most common side effects include:
  • Mild drowsiness (more common than with other second-generation antihistamines) 1
  • Headache 1
  • Pharyngitis 1
  • Abdominal pain 1
• Unlike first-generation antihistamines, cetirizine causes significantly less sedation at recommended doses 4
• Cetirizine has negligible anticholinergic effects and minimal penetration into the brain 3

Clinical Considerations

• Cetirizine is effective for treating:
  • Seasonal and perennial allergic rhinitis 5
  • Chronic idiopathic urticaria 5
  • Certain forms of physical urticaria 4
  • Atopic dermatitis (as an adjunct therapy) 6
• Cetirizine has anti-inflammatory properties that may provide additional benefit beyond the antihistamine effect 3
• The drug has a long history of safe use in children, with over 30 years of clinical experience 2

Important Monitoring

• Observe for drowsiness, especially during the first few days of treatment 1
• Monitor for improvement in allergy symptoms, which should begin within the first day of treatment 3
• No specific laboratory monitoring is required during cetirizine therapy 3