Cetirizine Dosing for 6-Month-Old Infants
Cetirizine is available for infants 6–11 months of age at a dose of 2.5 mg (approximately 2.5 mL of oral solution) given twice daily. 1, 2
Specific Dosing Regimen
- For infants aged 6–11 months, administer 2.5 mg (2.5 mL) twice daily (morning and evening), which corresponds to approximately 0.25 mg/kg per dose for an average-weight infant in this age range 3, 1
- The twice-daily dosing schedule is necessary in very young children due to rapid oral clearance compared to older patients 2
- Cetirizine oral drops are specifically formulated for precise dosing in this age group 1
Safety Profile in Young Infants
- Cetirizine has been demonstrated to be safe in infants 6–11 months in a randomized, double-blind, placebo-controlled trial, with no differences in adverse events between cetirizine and placebo groups 3
- No cardiac effects (specifically no QT prolongation) were observed in infants receiving cetirizine compared to placebo 3, 2
- The tolerability profile in infants aged 6–24 months is similar to placebo, with a trend toward fewer sleep-related disturbances in the cetirizine group 4, 3
- Second-generation antihistamines like cetirizine have a markedly better safety profile than first-generation antihistamines or over-the-counter cough/cold products, which should be avoided in children under 6 years 2, 5
Important Clinical Considerations
- Cetirizine is the only second-generation antihistamine with prospective, randomized, double-blind, placebo-controlled safety data in infants as young as 6 months 3
- The mean daily dose in the pivotal safety study was 4.5 mg (±0.7 mg SD), confirming the 2.5 mg twice-daily regimen 3
- Sedation risk in this age group appears lower than in older children and adults, where cetirizine causes sedation in approximately 13.7% versus 6.3% with placebo 2, 5
Critical Pitfall to Avoid
- Do not use cetirizine in infants younger than 6 months, as safety and efficacy have not been established in this population 3
- Do not use first-generation antihistamines (diphenhydramine, chlorpheniramine) or OTC cough/cold combination products in infants, as they lack proven efficacy and carry serious safety risks including fatal overdose 2, 5