What is the difference between Claritin (loratadine) and Zyrtec (cetirizine) for allergy symptom relief?

Claritin vs. Zyrtec for Allergy Symptom Relief

Zyrtec (cetirizine) is generally more effective than Claritin (loratadine) for allergy symptom relief, but has a higher risk of sedation at recommended doses. 1

Key Differences

Sedation Profile

• Loratadine (Claritin): Does not cause sedation at recommended doses; may cause sedation only at doses exceeding recommendations 1
• Cetirizine (Zyrtec): May cause sedation even at recommended doses (13.7% vs 6.3% for placebo) 1

Efficacy

• Multiple studies have found cetirizine to be superior to loratadine for symptom relief, though differences are not always statistically significant 1
• In controlled studies:
  • Cetirizine produced 36.7% reduction in total symptom scores vs 15.4% with loratadine 2
  • Cetirizine showed 25.4% reduction in symptoms vs 11.2% with loratadine in a confirmatory study 3

Onset of Action

• Cetirizine: Faster onset of action (within 1 hour) 2, 3
• Loratadine: Slower onset (approximately 3 hours) 2, 3

Clinical Decision Algorithm

Choose Claritin (loratadine) when:

• Patient needs to drive, operate machinery, or perform tasks requiring alertness
• Patient has previously experienced sedation with other antihistamines
• Patient has low body mass (higher risk of sedation with standard doses) 1
• Patient needs once-daily dosing (10mg daily) 4

Choose Zyrtec (cetirizine) when:

• Maximum symptom relief is the priority
• Rapid onset of action is needed
• Patient can tolerate potential mild sedation
• Patient has more severe allergy symptoms
• Patient will take medication before bedtime

Important Considerations

Specific Symptoms

• Both medications effectively treat:
  • Runny nose
  • Sneezing
  • Itchy, watery eyes
  • Itching of nose or throat 5, 6
• Cetirizine may be more effective for nasal discharge, sneezing, and itching/burning eyes 7

Cautions

• Sedation risk: Always warn patients about potential sedation with cetirizine 1
• Renal impairment: Cetirizine dose should be halved in moderate renal impairment; loratadine should be used with caution in severe renal impairment 1
• Pregnancy: Both should be used with caution, particularly in first trimester, though both are FDA Pregnancy Category B 1

Special Populations

• Children: Both are approved for children 6 years and older 6
• Elderly: Consider loratadine due to lower sedation risk, especially if cognitive concerns exist

By understanding these differences, you can select the antihistamine that best addresses your specific allergy symptoms while minimizing unwanted side effects.