From the Guidelines
Neither cetirizine nor fexofenadine works definitively better than the other for all people, as their effectiveness varies by individual. Both are second-generation antihistamines that treat allergy symptoms by blocking histamine receptors, but they have different characteristics. Cetirizine typically works faster (within 1 hour versus 2-3 hours for Allegra) and may be more effective for some people with severe allergy symptoms, as noted in a study published in the Journal of Allergy and Clinical Immunology 1. However, Allegra has a lower incidence of drowsiness (about 2% versus 14% for cetirizine) and fewer drug interactions.
Some key points to consider when choosing between cetirizine and fexofenadine include:
- Cetirizine is typically taken as a 10mg tablet once daily, while Allegra is usually taken as a 180mg tablet once daily or 60mg twice daily.
- Both medications can be taken with or without food, though Allegra's absorption may be reduced when taken with certain fruit juices.
- If one medication doesn't provide adequate relief, it's reasonable to try the other under medical guidance, as individual responses vary significantly, as discussed in the diagnosis and management of rhinitis: an updated practice parameter 1.
- It's also important to note that intranasal corticosteroids are the most effective medication class in controlling symptoms of allergic rhinitis, and may be considered in addition to or instead of antihistamines, as noted in a study on the diagnosis and management of rhinitis 1.
Ultimately, the choice between cetirizine and fexofenadine should be based on individual patient needs and medical history, and made in consultation with a healthcare professional.
From the Research
Comparison of Cetirizine and Fexofenadine (Allegra)
- Cetirizine and fexofenadine are both second-generation H1 antihistamines used to treat allergic rhinitis 2.
- Studies have shown that cetirizine is as effective as fexofenadine in relieving symptoms of seasonal allergic rhinitis (SAR) and perennial allergic rhinitis (PAR) 3, 4.
- However, one study found that cetirizine was more effective than fexofenadine in reducing symptoms of SAR at 12 hours postdose and over the 5- to 12-hour postdose period 5.
- Another study found that cetirizine was more effective than fexofenadine in relieving symptoms of runny nose, sneezing, itchy/watery eyes, and itchy nose/throat/palate 5.
- In terms of safety, both cetirizine and fexofenadine were well tolerated, with similar incidence of treatment-emergent adverse events and somnolence 4, 5.
Efficacy of Cetirizine
- Cetirizine has been shown to be effective in relieving symptoms of SAR, PAR, and chronic idiopathic urticaria (CIU) 6, 3.
- It has a rapid onset of action and a long duration of activity, making it a useful option for the treatment of allergic disorders 3.
- Cetirizine has also been shown to have a corticosteroid-sparing effect and reduce the relative risk of developing asthma in sensitized infants with atopic dermatitis 3.
Comparison with Other Antihistamines
- Cetirizine has been compared to other antihistamines, such as loratadine and ebastine, and has been found to be as effective or more effective in relieving symptoms of SAR and PAR 3.
- Cetirizine has also been compared to first-generation antihistamines, such as chlorpheniramine, and has been found to have a lower incidence of sedation and other adverse effects 6, 3.