What is the preferred treatment, Allegra (fexofenadine) or Zyrtec (cetirizine), for a patient with cold urticaria?

Fexofenadine (Allegra) is Preferred for Cold Urticaria

For cold urticaria, fexofenadine (Allegra) is the superior choice over cetirizine (Zyrtec) because it is completely non-sedating at all doses while maintaining equivalent efficacy, which is critical for patients who need consistent symptom control without impairment. 1

Rationale for Fexofenadine Selection

Non-Sedation Profile

• Fexofenadine remains completely non-sedating even at higher than recommended doses, making it ideal for dose escalation if needed 1, 2
• Cetirizine causes sedation in 13.7% of patients versus 6.3% with placebo, and this sedation risk increases significantly at higher doses 1
• This sedation difference becomes clinically critical because cold urticaria often requires dose escalation beyond standard dosing for adequate control 1

Efficacy in Urticaria

• Both agents are equally effective as first-line second-generation antihistamines for urticaria 3
• Fexofenadine 180 mg once daily demonstrates significant relief in chronic idiopathic urticaria with 95% patient-reported improvement 4
• Fexofenadine has rapid onset of action (≤2 hours) and long duration suitable for once-daily dosing 5

Treatment Algorithm for Cold Urticaria

Initial Therapy

• Start with fexofenadine 180 mg once daily 4, 5
• Allow 2-4 weeks to assess response before escalating 1

If Inadequate Control After 2-4 Weeks

• Increase fexofenadine up to 4-fold (720 mg daily) before switching treatments 1, 3
• The complete non-sedating profile of fexofenadine at all doses makes this escalation safer than with cetirizine 1

Adjunctive Therapy Options

• Consider adding zafirlukast (leukotriene receptor antagonist) to antihistamine therapy, as combination therapy with cetirizine and zafirlukast proved superior to either agent alone in severe cold urticaria 6
• Adding montelukast 10 mg equals the efficacy of doubled antihistamine doses with significantly less sedation 1

Second-Line Treatment

• If inadequate control persists despite 4-fold antihistamine dosing, advance to omalizumab 300 mg every 4 weeks 1, 3

Critical Pitfalls to Avoid

• Don't assume cetirizine and fexofenadine have identical side effect profiles - cetirizine's sedation potential is substantially higher, especially at the higher doses often needed for physical urticarias 1, 2
• Avoid NSAIDs and aspirin as they can worsen urticaria symptoms through cyclooxygenase inhibition 1, 3
• Don't combine first-generation antihistamines at bedtime with second-generation agents during the day, as first-generation agents cause prolonged daytime drowsiness 1
• Minimize aggravating factors including overheating, stress, and alcohol 1, 3

Special Considerations

Renal Impairment

• Fexofenadine dosing does not require adjustment in renal impairment 2
• Cetirizine dose must be halved in moderate renal impairment 3, 2

Quality of Life Impact

• Fexofenadine produces greater improvements in quality of life than loratadine to a clinically meaningful extent 5
• The absence of sedation with fexofenadine preserves patients' ability to work, drive, and perform daily activities without impairment 5