What is the recommended dose of cetirizine (antihistamine) for a 7 kg infant?

Cetirizine Dosing for a 7 kg Infant

For a 7 kg infant, the recommended dose of cetirizine is 2.5 mg (half of a 5 mg tablet or 2.5 mL of the liquid formulation) once daily.

Dosing Rationale

The appropriate dosing of cetirizine for infants is based on weight-based calculations:

• For infants weighing 6-11 months (typically 7-10 kg), the recommended dose is 0.25 mg/kg twice daily 1
• For a 7 kg infant, this calculates to approximately 1.75 mg twice daily or 3.5 mg total daily dose
• In clinical practice, this is typically rounded to 2.5 mg once daily for ease of administration and to minimize sedation risk

Administration Considerations

• Cetirizine is available as:

  • Oral liquid: 5 mg/5 mL (1 mg/mL)
  • Chewable tablets: 5 mg and 10 mg
  • Regular tablets: 5 mg and 10 mg

• For a 7 kg infant, use the liquid formulation for accurate dosing

• Administer 2.5 mL (2.5 mg) of the liquid formulation once daily

Safety Profile in Infants

Safety data supports the use of cetirizine in infants:

• A randomized, double-blind, placebo-controlled study specifically evaluated cetirizine in infants 6-11 months of age and found no significant difference in adverse events between cetirizine and placebo 1
• The ETAC study (Early Treatment of the Atopic Child) demonstrated the long-term safety of cetirizine in children 12-24 months of age over an 18-month period 2
• No clinically relevant differences were found in neurologic or cardiovascular symptoms, growth, behavioral or developmental assessments, or laboratory test results compared to placebo 2

Clinical Considerations

• Cetirizine is a second-generation antihistamine with minimal CNS penetration at recommended doses 3
• Unlike first-generation antihistamines, cetirizine causes less sedation at standard doses, making it more appropriate for daytime use 4
• However, cetirizine may still cause mild sedation in some infants (13.7% vs 6.3% with placebo in older children) 4

Monitoring and Precautions

• Monitor for sedation, which is the most common side effect

• Watch for less common side effects such as:

  • Paradoxical excitation or agitation (rare in infants) 5
  • Dry mouth (anticholinergic effect) 3
  • Gastrointestinal symptoms

• No specific laboratory monitoring is required during cetirizine therapy 4

Important Caveats

• Avoid exceeding the recommended dose as higher doses increase the risk of sedation 4
• In case of accidental overdose, drowsiness and sedation are the primary concerns, with minimal risk of cardiac events 6
• For infants with renal impairment, dose adjustment may be necessary
• If treating allergic reactions, remember that antihistamines should not be used as monotherapy for anaphylaxis (epinephrine is first-line) 4, 5

Cetirizine is generally well-tolerated in infants and provides effective symptom relief for allergic conditions with a favorable safety profile compared to first-generation antihistamines.