What is the recommended dosing for Zyrtec (cetirizine)?

Cetirizine (Zyrtec) Dosing Recommendations

The standard recommended dose of cetirizine (Zyrtec) for adults and children 6 years and older is 5-10 mg once daily, with 10 mg being the most commonly prescribed dose.

Adult Dosing

• Standard dose: 10 mg once daily
• Elderly patients: Consider starting at 5 mg once daily
• Maximum daily dose: 10 mg

Pediatric Dosing

• Children 6 years and older: 5-10 mg once daily
• Children 2-5 years: 2.5 mg once daily, may increase to 5 mg once daily or 2.5 mg twice daily
• Children 12-24 months: 0.125 mg/kg twice daily 1
• Children 6-11 months: Not recommended unless directed by physician

Special Populations

Renal Impairment

• Moderate renal impairment (creatinine clearance 10-30 mL/min): Reduce dose by 50% (5 mg once daily) 2
• Severe renal impairment (creatinine clearance <10 mL/min): Avoid use 2
• Hemodialysis patients: 5 mg once daily

Hepatic Impairment

• No specific dose adjustment required for mild to moderate hepatic impairment
• Use with caution in severe hepatic disease

Pregnancy

• Best to avoid all antihistamines in pregnancy, especially during the first trimester 2
• If antihistamine therapy is necessary during pregnancy, consider alternatives with longer safety records

Administration Guidelines

• Can be taken with or without food
• Onset of action is rapid, typically within 20-60 minutes 3
• Duration of effect is approximately 24 hours, allowing for once-daily dosing
• Available as tablets, chewable tablets, and oral solution

Clinical Pearls

• Cetirizine may cause mild sedation in some patients, especially at higher doses 2
• Unlike some other second-generation antihistamines, cetirizine may cause drowsiness at recommended doses in approximately 13.7% of patients compared to 6.3% with placebo 2
• For patients experiencing sedation with cetirizine, consider:
  1. Reducing the dose to 5 mg
  2. Taking the medication at bedtime
  3. Switching to a less sedating alternative like fexofenadine

Monitoring

• No routine laboratory monitoring required
• Assess for symptom control and side effects at follow-up visits
• If skin testing is planned, cetirizine should be discontinued at least 3 days before testing

Cetirizine is a potent H1-receptor antagonist with excellent efficacy for allergic conditions including allergic rhinitis and urticaria 3. Its pharmacokinetic profile allows for once-daily dosing with consistent 24-hour symptom control.