Cetirizine Dosing for 16-Month-Old, 10.5 kg Child
For a 16-month-old child weighing 10.5 kg, administer 2.5 mL of cetirizine oral solution (1 mg/mL concentration) once daily, which provides the standard 2.5 mg dose for children aged 12-23 months.
Age-Appropriate Dosing
Children aged 12-23 months (which includes your 16-month-old patient) should receive 2.5 mg once daily of cetirizine 1, 2.
This translates to 2.5 mL of the standard oral solution (1 mg/mL concentration, which is the typical syrup formulation available) 1.
The dose is based on age rather than weight for this age group, as the 10.5 kg weight falls within the normal range for a 16-month-old 3.
Formulation and Administration
Cetirizine oral solution is typically available as a 1 mg/mL syrup formulation 1.
The medication can be administered without regard to meals, though giving it with food may improve tolerability if any gastrointestinal upset occurs 3.
Use an accurate measuring device (oral syringe preferred) rather than household spoons to ensure precise dosing 1.
Clinical Efficacy and Safety Profile
Cetirizine demonstrates rapid onset of action within 20 minutes of administration and maintains efficacy for 24 hours, making once-daily dosing appropriate 3.
In infants aged 6-24 months, the tolerability profile is similar to placebo, with no adverse effects on cognitive function, behavior, or achievement of psychomotor milestones 1.
The medication is predominantly eliminated by the kidneys with a mean half-life of approximately 8.3 hours 3, 4.
Important Safety Considerations
No dose adjustment is needed for this child's weight of 10.5 kg, as dosing for children 12-23 months is standardized at 2.5 mg once daily regardless of weight within the normal range 1.
Somnolence is the most common side effect and is dose-related, though at the 2.5 mg dose for infants, the incidence is comparable to placebo 1.
Cetirizine has negligible CNS penetration due to its zwitterionic structure and P-glycoprotein activity, resulting in minimal sedation compared to first-generation antihistamines 4.
Common Pitfalls to Avoid
Do not use adult dosing (10 mg) or older pediatric dosing (5 mg for ages 2-5 years) for this age group, as the 2.5 mg dose is specifically established for 12-23 month-olds 1, 2.
Avoid twice-daily dosing in this age group—the 2.5 mg once-daily regimen is the appropriate frequency for children under 2 years 1.
Do not calculate weight-based dosing for cetirizine in children under 2 years, as age-based dosing is the standard approach for this medication in this population 3.
Ensure renal function is normal before dosing, as cetirizine is predominantly renally eliminated and dose adjustment would be required in renal insufficiency 3, 4.