From the Guidelines
Cetirizine hydrochloride and fexofenadine HCl are both second-generation antihistamines used to treat allergy symptoms, but cetirizine tends to cause more drowsiness than fexofenadine, which is considered one of the least sedating antihistamines 1.
Key Differences
- Cetirizine may work faster, typically within 1 hour, while fexofenadine usually takes effect within 1-2 hours.
- The typical adult dose for cetirizine is 5-10 mg once daily, while fexofenadine is usually taken as 60 mg twice daily or 180 mg once daily.
- Cetirizine may be more effective for some people with severe allergies, but fexofenadine might be preferable for those who need to remain alert during the day or operate machinery.
Mechanism of Action
Both medications work by blocking histamine receptors to reduce allergy symptoms like sneezing, itching, watery eyes, and runny nose, but they have different chemical structures that account for their varying side effect profiles and onset of action 1.
Sedative Properties
The use of fexofenadine, loratadine, and desloratadine when used at recommended doses for the treatment of allergic rhinitis has not been associated with sedative properties compared with placebo, while cetirizine has been associated with sedative properties compared with placebo, although the effect tends to be milder than that observed with first-generation antihistamines 1.
Efficacy
Among the newer, nonsedating antihistamines, no single agent has been conclusively shown to have superior efficacy, although some studies have found cetirizine to be superior to loratadine 1.
From the Research
Comparison of Cetirizine Hydrochloride and Fexofenadine HCl
- Cetirizine and fexofenadine are both used to treat seasonal allergic rhinitis and chronic idiopathic urticaria, but they have some differences in terms of efficacy and side effects 2, 3, 4, 5, 6.
- Fexofenadine is a selective histamine H1 receptor antagonist that does not cross the blood-brain barrier, making it less likely to cause drowsiness compared to cetirizine 2.
- Studies have shown that fexofenadine and cetirizine have similar efficacy in treating seasonal allergic rhinitis, but cetirizine may have a longer duration of effect 4, 5.
- In terms of side effects, fexofenadine has been shown to cause less drowsiness compared to cetirizine 3.
- A study comparing the efficacy of cetirizine and fexofenadine in the treatment of chronic idiopathic urticaria found that cetirizine had a therapeutic advantage over fexofenadine 6.
Efficacy Comparison
- A study found that cetirizine produced a 26% greater reduction in total symptom severity complex (TSSC) score at 12 hours postdose compared to fexofenadine 4.
- Another study found that cetirizine had a 33% greater reduction in TSSC score over the 21- to 24-hour interval after the first dose compared to fexofenadine 5.
- Fexofenadine has been shown to be as effective as loratadine and cetirizine in treating seasonal allergic rhinitis 2.