Key takeaways
Levocetirizine (Xyzal Allergy) and fexofenadine (Allegra) are both third-generation antihistamines used to relieve allergy symptoms and hives. But they have several differences. Both generic forms are available over-the-counter and by prescription. Levocetirizine typically starts working faster, within about 1 hour, compared to fexofenadine, which takes about 2 hours. However, levocetirizine is more likely to cause drowsiness than fexofenadine. Levocetirizine is taken once daily, usually in the evening, whereas fexofenadine can be taken once or twice daily depending on the formulation. Both medications come in various forms, but fexofenadine offers a fast-melting tablet option, which might be easier for some people to take. Both medications may cause more side effects if you have kidney problems.
