From the Guidelines
Allegra (fexofenadine) is the recommended choice for patients who need to remain alert, as it is generally the least sedating option among the three, with studies showing no sedative properties at recommended doses 1. When considering Xyzal (levocetirizine), Allegra (fexofenadine), and Zyrtec (cetirizine) for allergy symptoms, it's essential to weigh their differences.
- Zyrtec typically provides strong symptom relief but may cause more drowsiness (in about 10-15% of users) 1.
- Xyzal works similarly to Zyrtec but with potentially fewer side effects and a slightly faster onset.
- Allegra is ideal for those who need to remain alert, as it is less likely to cause sedation, though it may offer slightly less powerful symptom control for some people. Key considerations include:
- Dosage: Zyrtec and Xyzal are usually taken in the evening (5mg-10mg for Zyrtec, 5mg for Xyzal), while Allegra (180mg) can be taken any time of day.
- Administration: Allegra should be taken on an empty stomach or with water only, as fruit juices can reduce its effectiveness.
- Efficacy: While no single agent has been conclusively shown to have superior overall response rates among the newer, nonsedating antihistamines 1, cetirizine has been found superior to loratadine in some studies 1. Given the potential for sedation and performance impairment associated with some of these medications, it is crucial to choose the one that best aligns with the patient's needs and lifestyle, prioritizing factors such as sedation risk and symptom control 1.
From the Research
Comparison of Xyzal, Allegra, and Zyrtec
- Xyzal (levocetirizine) and Zyrtec (cetirizine) are both second-generation antihistamines, while Allegra (fexofenadine) is also a second-generation antihistamine 2, 3, 4.
- Cetirizine (Zyrtec) has been shown to be effective in treating seasonal allergic rhinitis, perennial allergic rhinitis, and chronic idiopathic urticaria in adults, adolescents, and pediatric patients 5, 2.
- Fexofenadine (Allegra) has been compared to cetirizine (Zyrtec) in several studies, with cetirizine showing greater efficacy in relieving symptoms of seasonal allergic rhinitis at 12 hours postdose and over the 5- to 12-hour postdose period 3.
- Cetirizine (Zyrtec) has also been shown to have anti-inflammatory properties, which may play a role in asthma management, and does not interact with concomitantly administered medications 4.
- Levocetirizine (Xyzal) is the R-enantiomer of cetirizine (Zyrtec) and has been shown to be effective in treating allergic rhinitis and urticaria, but there is limited direct comparison with fexofenadine (Allegra) and cetirizine (Zyrtec) in the provided studies.
Treatment of Allergic Rhinitis
- Second-generation H1 antihistamines, such as cetirizine (Zyrtec), fexofenadine (Allegra), and levocetirizine (Xyzal), are recommended as first-line treatment for mild intermittent or mild persistent allergic rhinitis 6.
- Intranasal corticosteroids, such as fluticasone and triamcinolone, are recommended as first-line treatment for persistent moderate to severe allergic rhinitis, and may be used in combination with an intranasal antihistamine or a second-generation H1 antihistamine 6.