Weight-Based Therapeutic Dosing for Cetirizine Syrup and Drops
The recommended weight-based therapeutic dosing for cetirizine syrup and drops is 0.25 mg/kg twice daily for infants 6-11 months, and age-appropriate dosing for older children with adjustments based on weight. 1
Pediatric Dosing Guidelines by Age Group
Infants (6-11 months)
- 0.25 mg/kg cetirizine orally twice daily 1
- Average daily dose in clinical studies: 4.5 mg ± 0.7 mg 1
- Available as oral drops for precise dosing in this age group 2
Children (2-6 years)
- 5 mg once daily (approximately 0.32 mg/kg) 3
- May be administered as syrup formulation for easier administration 3
- Note: Elimination half-life is shorter in children (5.55 ± 0.98 hours) compared to adults, which may necessitate twice daily dosing in some cases 3
Children (6-12 years)
- 5-10 mg once daily depending on symptom severity 4
- Pharmacokinetic studies show rapid absorption with peak concentrations of 427.6 ± 144.2 ng/ml after 5 mg dose 4
- Effective suppression of histamine-induced wheal-and-flare reactions from 1 to 24 hours after a 5 mg dose 4
Adolescents (>12 years) and Adults
- 10 mg once daily, standard adult dosing 5
- May be increased above licensed recommendation for patients who do not respond adequately 5
Administration Considerations
- For optimal symptom control, cetirizine can be administered in the evening if drowsiness occurs 2
- Cetirizine has a shorter time to maximum concentration compared to other antihistamines, which may be advantageous when rapid symptom relief is needed 5
- Dosing should be adjusted in patients with renal impairment - halve the dose in moderate renal impairment (creatinine clearance 10-20 mL/min) 5
- Avoid use in severe renal impairment (creatinine clearance <10 mL/min) 5
Safety Profile
- Generally well-tolerated in children with a safety profile comparable to placebo 2
- May cause mild drowsiness in approximately 13.7% of pediatric patients compared to 6.3% with placebo 2
- Most common side effects include headache, pharyngitis, and abdominal pain 2
- No prolongation in QT interval observed in cetirizine-treated infants in controlled studies 1
- Unlike some first-generation antihistamines, cetirizine has minimal anticholinergic effects 6
Clinical Pearls
- For urticaria management, cetirizine is effective as a first-line treatment 5
- In dermatologic conditions, cetirizine 10 mg daily is recommended for adults, with weight-appropriate dosing for children 5
- When treating allergic rhinitis in children, cetirizine has demonstrated efficacy comparable to other second-generation antihistamines 7
- Cetirizine has antiallergic properties beyond H1-receptor antagonism, including inhibition of eosinophil chemotaxis during allergic responses 6, 7
Cautions
- Avoid use during pregnancy, especially in the first trimester, unless clearly necessary 5
- Consider potential sedative effects when prescribing for school-age children, as it may affect school performance 5
- Despite being classified as a second-generation antihistamine, cetirizine may cause more sedation than other medications in this class 2