What is the recommended pediatric dosing of Zyrtec (cetirizine) for children aged 2 years and older?

Recommended Pediatric Dosing for Zyrtec (Cetirizine)

For children aged 2–5 years, start with cetirizine 2.5 mg (approximately 2.5 mL syrup) once daily, which can be increased to a maximum of 5 mg per day if needed for symptom control. 1, 2

Age-Based Dosing Algorithm

Children 6 months to <2 years

• Infants 6–11 months: Use cetirizine oral drops at 0.25 mg/kg twice daily (morning and evening), with a typical volume of 2.5–3.5 mL per dose 1, 2
• Infants 12–24 months: Continue 0.25 mg/kg twice daily dosing; twice-daily administration is necessary due to rapid oral clearance in very young children 2
• Long-term safety has been established in this age group through the ETAC trial 2, 3

Children 2–5 years

• Starting dose: 2.5 mg once daily (preferably in the evening) 1, 2
• Dose escalation: If symptoms remain uncontrolled after 3–5 days, increase to 5 mg once daily OR split into 2.5 mg twice daily 2
• Maximum dose: 5 mg per day total; do not exceed this limit as higher doses increase sedation risk without additional benefit 2

Children 6–11 years

• Recommended dose: 5–10 mg once daily 4
• The 10 mg dose provides significantly greater symptom reduction than 5 mg and is well tolerated 4

Adolescents ≥12 years and Adults

• Standard dose: 10 mg once daily 1

Critical Safety Considerations

Sedation Management

• Cetirizine causes sedation in approximately 13.7% of patients ≥12 years versus 6.3% with placebo; the risk is lower in younger children 5, 2, 6
• If significant drowsiness occurs: Reduce to 2.5 mg once daily OR switch to a non-sedating antihistamine (loratadine or fexofenadine) 2
• Timing strategy: Administer in the evening to minimize impact on school performance and daytime activities 1, 6

Dosing Pitfalls to Avoid

• Use age-based dosing, NOT weight-based calculations in low-weight children to prevent inadvertent overdosing and increased sedation 2
• Never use first-generation antihistamines or OTC cough/cold combination products in children <6 years due to lack of efficacy and serious safety risks, including fatal overdoses 5, 2
• Second-generation antihistamines like cetirizine have a markedly superior safety profile compared to these alternatives 5, 2

Special Population Adjustments

Renal impairment:

• Moderate impairment (CrCl 10–50 mL/min): Reduce dose by 50% to 5 mg once daily 1
• Severe impairment (CrCl <10 mL/min): Avoid cetirizine entirely 1

Pregnancy:

• FDA Category B; avoid if possible, especially in first trimester 1, 2

Evidence Quality Notes

The dosing recommendations are supported by high-quality guideline evidence from the American Academy of Allergy, Asthma, and Immunology 1, 2 and the Journal of Allergy and Clinical Immunology 5. The ETAC study provides the strongest prospective safety data for infants 12–24 months, representing the largest and longest randomized controlled trial of any H1-antihistamine in young children 2, 3. No cardiac effects (QT prolongation) have been observed in infants receiving cetirizine 2, 7.