Hydroxyzine Dosing for a 13-kg, 3-Year-Old Child
For a 13-kg, 3-year-old child, the appropriate dose of oral hydroxyzine (6 mg/mL) depends on the indication: for anxiety/sedation give 50 mg daily in divided doses (approximately 8.3 mL total per day split into 2-4 doses), or for pruritus/allergic conditions give 50 mg daily in divided doses (approximately 8.3 mL total per day split into 3-4 doses). 1
Dosing by Indication
The FDA-approved dosing for hydroxyzine in children under 6 years is indication-specific 1:
For Anxiety and Tension
- Children under 6 years: 50 mg daily in divided doses
- For this 13-kg child: 50 mg/day total = 8.3 mL/day of the 6 mg/mL solution
- Divide into 4 doses (q.i.d.): approximately 2 mL per dose, four times daily
- This equals approximately 12 mg per dose
For Pruritus (Allergic Conditions, Urticaria, Dermatoses)
- Children under 6 years: 50 mg daily in divided doses
- For this 13-kg child: 50 mg/day total = 8.3 mL/day of the 6 mg/mL solution
- Divide into 3-4 doses (t.i.d. or q.i.d.): approximately 2-2.8 mL per dose
- This equals approximately 12-17 mg per dose
For Preoperative Sedation
- 0.6 mg/kg body weight
- For this 13-kg child: 0.6 mg/kg × 13 kg = 7.8 mg = 1.3 mL as a single dose 1
Practical Calculation
Using the 6 mg/mL concentration:
- 50 mg ÷ 6 mg/mL = 8.3 mL total daily dose
- Split into 4 doses: 2 mL per dose (12 mg per dose)
- Split into 3 doses: 2.8 mL per dose (17 mg per dose)
Important Clinical Considerations
The dosage should be adjusted according to the patient's response to therapy 1. Research supports that hydroxyzine 0.7 mg/kg three times daily (which would be approximately 9 mg TID for this child) is effective for pruritus in children with atopic dermatitis, with peak serum concentrations occurring at 2 hours and elimination half-life of approximately 7 hours 2.
Common Pitfalls to Avoid
- Do not exceed the recommended daily dose of 50 mg for children under 6 years regardless of weight-based calculations that might suggest higher doses
- The FDA label specifies fixed daily doses for age groups rather than strict weight-based dosing for chronic use 1
- Monitor for sedation, which is the most common adverse effect 2
- Hydroxyzine has anticholinergic effects, so be cautious in patients with conditions that could be worsened by these effects 3
Onset and Duration
Hydroxyzine is rapidly absorbed with clinical effects typically noted within 15-30 minutes after oral administration 1. In pediatric studies, pruritus suppression was significant from 1-24 hours after dosing, with greater than 85% suppression from 2-12 hours 2.