Ashley asked
I want to take Zyrtec and Allegra at the same time as I imagine they will work better together. Can I safely combine them?
Answer
Typically, it is not recommended to use cetirizine (Zyrtec) and fexofenadine (Allegra) at the same time. Both medications are second-generation antihistamines used for allergy relief. Taking them together would not provide much added benefit, but could lead to side effects such as drowsiness.
In some patients, Zyrtec may work better than Allegra, however, it also may also cause drowsiness. Zyrtec, Claritin, and Allegra are second-generation antihistamines and are still less likely to cause drowsiness than first-generation antihistamines such as Benadryl (diphenhydramine). This is because first-generation antihistamines cross the blood-brain barrier, whereas the second-generation antihistamines usually do not.
When taking fexofenadine (Allegra) it is important to avoid grapefruit, orange, and
apple juice as these are known to decrease intestinal absorption. Avoid
these juices at least 4 hours before and 2 hours after taking Allegra.
How Antihistamines Work
Antihistamines bind to histamine receptors that are found in the nose, lungs, eyes, and skin without activating the histamine response. By binding and changing the shape of the histamine receptor, antihistamines inhibit histamine from binding and creating its response. Histamine creates an immune response to essentially attempt to remove the offensive allergen.
Histamine can be triggered by a variety of things including
pollen, dust, and pet dander. Some people are more sensitive to this response
and may not even know what triggers their allergies. Antihistamines are useful
in preventing the immune cascade so common in people suffering from allergies.
Flonase As An Alternative
Another option would be to switch or add fluticasone
(Flonase) nasal spray. Flonase was approved by the FDA in 1990, but has only
been available over-the-counter since 2014. Flonase is a type of steroid that
blocks inflammation, itching, and congestion.
According to the Flonase website, it has some advantages over Claritin
including working better for nasal congestion. Flonase can be used once daily
with 1 or 2 sprays into each nostril or may be used as needed instead of every
day.
Conclusion
To conclude, it is not recommended to take both Zyrtec and
Allegra together due to the possibility of drowsiness without additional
benefit. Flonase nasal spray may be another option to provide an alternative mechanism
of action against allergies.
