From the Guidelines
It is generally not recommended to take Zyrtec (cetirizine) and Allegra (fexofenadine) at the same time. Both medications are second-generation antihistamines that work in similar ways to block histamine receptors and relieve allergy symptoms. Taking them together doesn't provide additional benefit but may increase the risk of side effects such as drowsiness, dry mouth, headache, and dizziness.
Key Points to Consider
- Instead, choose one antihistamine and take it as directed - Zyrtec is typically taken once daily at a dose of 10mg for adults, while Allegra is usually taken at 60mg twice daily or 180mg once daily for adults.
- If one medication doesn't adequately control your allergy symptoms, consult with your healthcare provider who might recommend switching to a different antihistamine or adding a different type of allergy medication like a nasal corticosteroid or decongestant.
- Each person responds differently to antihistamines, so finding the right one for your specific allergy symptoms may require some trial and adjustment under medical supervision.
Evidence-Based Recommendations
According to the most recent guidelines from the Joint Task Force on Practice Parameters 1, for initial treatment of seasonal allergic rhinitis in persons aged 12 years or older, monotherapy with an intranasal corticosteroid is recommended over an oral antihistamine.
Important Considerations
- The 2017 guideline from the Joint Task Force on Practice Parameters 1 also recommends an intranasal corticosteroid over a leukotriene receptor antagonist for initial treatment of seasonal allergic rhinitis in persons aged 15 years or older.
- For treatment of moderate to severe seasonal allergic rhinitis, the combination of an intranasal corticosteroid and an intranasal antihistamine may be considered for initial treatment 1.
From the Research
Medication Interaction
- Zyrtec (cetirizine) and Allegra (fexofenadine) are both second-generation H1 antihistamines used to treat allergic rhinitis symptoms 2, 3.
- There is no direct evidence in the provided studies that addresses the safety and efficacy of taking Zyrtec and Allegra at the same time.
Efficacy Comparison
- Studies have compared the efficacy of cetirizine and fexofenadine in treating seasonal allergic rhinitis, with cetirizine showing a longer duration of effect and greater relief of symptoms in some cases 4, 5, 6.
- Cetirizine was found to be more effective than fexofenadine in reducing total symptom severity complex (TSSC) scores at 12 hours postdose and over the 5- to 12-hour postdose period 4.
- Fexofenadine, on the other hand, has been shown to be effective in alleviating symptoms of allergic rhinitis and improving quality of life, with a favorable safety profile 3.