Cetirizine Dosing for a 5-Year-Old Weighing 43.8 Pounds
Give 5 mL of cetirizine oral solution (assuming standard 5 mg/5 mL concentration) once daily.
Weight-Based Dosing Calculation
A 43.8 lb child falls into the >40 kg weight category according to standard pediatric dosing guidelines, though this appears to be an error in the question since 43.8 lbs = 19.9 kg 1
For a child weighing 19.9 kg (43.8 lbs), which falls in the >15-23 kg range, the appropriate dose is 5 mg once daily 2, 3, 4
Using standard cetirizine oral solution (5 mg/5 mL concentration), this equals 5 mL once daily 2
Key Dosing Principles
Cetirizine is dosed once daily due to its 24-hour duration of action and elimination half-life of approximately 8 hours 5, 3
The medication can be given without regard to meals, though administration with food may improve tolerability if gastrointestinal upset occurs 2
Onset of action occurs within 20 minutes, with peak effect at 1 hour and sustained activity for 24 hours 3
Important Clinical Considerations
No dose adjustment is needed for age alone in children over 6 months 2, 3
The standard pediatric dose of 5 mg (5 mL of 5 mg/5 mL solution) is appropriate for children aged 2-5 years weighing 15-23 kg 2, 4
Cetirizine has minimal CNS penetration compared to first-generation antihistamines, with sedation rates comparable to placebo in most pediatric studies 6, 5
Monitor for dose-related somnolence, particularly after initial doses, though this is uncommon at standard dosing 2, 3