Cetirizine Dosage for Infants
For infants, cetirizine should be dosed at 0.25 mg/kg twice daily, which is approximately 2.5 mg once daily for most infants 6-11 months of age. 1
Dosing Guidelines for Cetirizine in Infants
Recommended Dosage
- Infants 6-11 months: 0.25 mg/kg twice daily 1
- This typically equals about 2.5 mg per day total
- Available as oral liquid drops or syrup formulations
Evidence Supporting This Recommendation
The safety of cetirizine in infants has been established in a randomized, double-blind, placebo-controlled study specifically examining infants 6-11 months of age. In this study, infants received 0.25 mg/kg cetirizine orally twice daily for one week, with a mean daily dose of 4.5 mg ± 0.7 mg. No significant differences in adverse events were observed between cetirizine and placebo groups, and importantly, no QT interval prolongation was noted 1.
Pharmacokinetics in Young Children
Cetirizine is rapidly absorbed, with significant clinical inhibition of histamine response occurring within 20 minutes of administration in infants and children. The antihistamine effect persists for 24 hours, and the mean elimination half-life is approximately 8.3 hours 2.
Safety Considerations
Advantages of Cetirizine for Infants
- Minimal penetration into the brain, resulting in less sedation compared to first-generation antihistamines 2
- No significant cardiac adverse effects 2
- Predominantly eliminated by the kidneys 2
Potential Side Effects
- Generally well-tolerated in infants
- A trend toward fewer sleep-related disturbances compared to placebo has been observed in infant studies 1
- In older children, cetirizine 10 mg may be associated with mild drowsiness (13.7%) compared to placebo (6.3%) 3
Special Considerations
- Renal impairment: The dose should be halved in moderate renal impairment (creatinine clearance 10-20 mL/min) and avoided in severe renal impairment 3
- Hepatic impairment: No specific dose adjustment needed for mild hepatic impairment 3
Clinical Application
When prescribing cetirizine for infants:
- Calculate the dose based on weight (0.25 mg/kg twice daily)
- Use appropriate pediatric formulation (liquid drops/syrup)
- Monitor for any adverse effects, though these are uncommon
- Reassess clinical response after 1-2 weeks of therapy
Comparative Data
For infants and young children, cetirizine has been shown to be effective and well-tolerated. A related medication, levocetirizine (the R-enantiomer of cetirizine), has also been studied in young children aged 1-2 years at a dose of 0.125 mg/kg twice daily with good safety profile 4.
While multiple second-generation antihistamines are available, cetirizine has specific evidence supporting its use in the infant population, making it a preferred choice when antihistamine therapy is indicated in this age group.