What is the recommended dose of Cetirizine (antihistamine) for pediatric patients?

Cetirizine Dosing in Pediatric Patients

For children 6 years and older, cetirizine 10 mg once daily is the recommended dose, while children 2-5 years should receive 5 mg once daily (or 2.5 mg twice daily), and infants 6-11 months require 0.25 mg/kg twice daily using oral drops. 1, 2

Age-Based Dosing Algorithm

Infants 6-11 Months

• Dose: 0.25 mg/kg twice daily (mean daily dose approximately 4.5 mg) 3
• Must use oral drops formulation for precise weight-based dosing 2
• This dosing has been validated in randomized, double-blind, placebo-controlled trials specifically in this age group 3

Children 2-5 Years (Preschool)

• Dose: 5 mg once daily 4, 5
• Alternative: 2.5 mg twice daily may be considered, though once-daily dosing improves compliance 6
• Studies in preschool children with chronic urticaria demonstrate safety and efficacy at 5 mg daily 4

Children 6-11 Years

• Dose: 10 mg once daily 1, 7
• 5 mg once daily may be appropriate for less severe symptoms, though clinical trials show 10 mg provides significantly greater symptom reduction (mean TSS reduction 3.2 vs placebo, P < 0.05) 7
• The 5 mg dose did not differ statistically from placebo in controlled trials 7

Children 12 Years and Older

• Dose: 10 mg once daily (same as adult dosing) 1, 2

Critical Dosing Considerations

Renal Impairment

• Moderate impairment (CrCl 10-50 mL/min): Reduce dose by 50% to 5 mg once daily 8, 2
• Severe impairment (CrCl <10 mL/min): Avoid cetirizine entirely 8, 2
• Cetirizine is predominantly renally excreted with a mean half-life of 8.3 hours 2

Weight-Based Dosing in Very Young Children

• In children 14-46 months, levocetirizine (active enantiomer) oral clearance increases by 0.044 L/h/kg with increasing body weight 6
• Twice-daily dosing is necessary in very young children due to rapid clearance 6
• Patients with low body mass may reach elevated dosage levels (mg/kg basis) with standard age-based dosing, potentially developing drowsiness 9

Timing and Administration

Optimal Timing

• If sedation occurs (13.7% of patients vs 6.3% placebo), administer in the evening 2, 10
• Evening dosing prevents negative effects on school performance if sedation develops 2
• Cetirizine has the shortest time to maximum concentration among second-generation antihistamines, advantageous for rapid symptom control 2

Common Pitfalls to Avoid

Underdosing in School-Age Children

• Do not use 5 mg in children 6-11 years expecting efficacy - this dose failed to show statistical difference from placebo in controlled trials 7
• The 10 mg dose is required for significant symptom improvement in this age group 7

Sedation Management

• Approximately 13.7% of pediatric patients experience mild drowsiness 10, 2
• If persistent sedation occurs despite evening dosing, switch to fexofenadine or loratadine rather than continuing suboptimal therapy 10
• Do not combine with other sedating medications without considering additive CNS effects 2

Pregnancy and Lactation

• Avoid all antihistamines during pregnancy, especially first trimester, though cetirizine is FDA Pregnancy Category B 8, 2
• When antihistamine therapy is deemed necessary, chlorphenamine is often chosen in the UK due to long safety record 8

Special Clinical Scenarios

Refractory Cases

• Dose escalation up to 40 mg daily is supported for non-responders (Quality of evidence III, Strength of recommendation C) 2
• Higher doses significantly improve symptoms but increase sedative effects 10

Hepatic Impairment

• While specific pediatric dosing adjustments are not established, cetirizine should be used with caution 8
• Avoid in severe liver disease where sedating effects are inappropriate 8