Can You Take Zyrtec-D Or Allegra-D With Amoxicillin?

In our latest question and answer, our pharmacist discusses whether or not it is safe to take Zyrtec-D/Allegra-D with amoxicillin.


Can I take Allegra-D or Zyrtec-D while taking amoxicillin and Flonase for treating a sinus infection?

Asked by Christina On Jan 19, 2023

Answered by
Medical Content Reviewed By HelloPharmacist Staff

Published Jan 20, 2023
Last updated Jan 20, 2023

Key points

  • There is no known interaction between Zyrtec-D/Allegra-D and amoxicillin.


Thanks for reaching out to us! Great question!

It is generally safe to take Allegra-D (fexofenadine; pseudoephedrine) or Zyrtec-D (cetirizine; pseudoephedrine) while taking amoxicillin as there are no known interactions between these medications. Additionally, Flonase is also safe to use with these medications. 

In fact, each of these medications can be helpful in treating the symptoms you may be experiencing from your sinus infection.

What Is Allegra-D & Zyrtec-D?

Both Allegra-D and Zyrtec-D are combination products that contain an antihistamine and a decongestant.

Antihistamines work by blocking the effects of histamine, which is a chemical stored in a variety of cell types (e.g., mast cells and basophils), and is released when the body is exposed to an allergen. Histamine is responsible for causing a variety of symptoms such as sneezing, itching, and a runny nose and blocking it helps to resolve these symptoms.

The decongestant contained in these products, pseudoephedrine, helps to relieve nasal congestion caused by a variety of reasons, such as an infection or due to allergies.

Taking these medications can be helpful in relieving symptoms associated with a sinus infection without affecting the antibiotic (amoxicillin in this case) you are taking.

Fexofenadine (the antihistamine in Allegra) and Cetirizine (the antihistamine in Zyrtec) are very similar in that they are both 'second-generation' antihistamines. They both have a long duration of action (around 24 hours, depending on the dose) and are less sedating than first-generation antihistamines, like Benadryl.

What Is Amoxicillin?

Amoxicillin is an antibiotic derived from penicillin that is used to treat some bacterial infections, including sinus infections.

It works by killing the bacteria that are causing the infection by binding to specific proteins in the cell wall, eventually causing it to rupture, killing the bacteria.

Final Words

As mentioned, there are no known interactions between Allegra-D, Zyrtec-D, amoxicillin, or Flonase. However, it is always best to consult with your doctor or pharmacist who knows your medical history before taking any new medications, especially if you have any pre-existing conditions or are taking other medications.

Additionally, only take one antihistamine/decongestant combination (i.e., either Zyrtec-D or Allegra-D) and not both at the same time.

Thanks so much for connecting with us and reach back out anytime.


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Dr. Brian Staiger, PharmD

Dr. Brian has been practicing pharmacy for over 13 years and has wide-ranging experiences in many different areas of the profession. From retail, clinical, program development, and administrative responsibilities, he's your knowledgeable and go-to source for all your pharmacy and medication-related questions! Dr. Brian Staiger also has herbalist training and educational certificates in the field of medical ethnobotany. Feel free to send him an email at! You can also connect with Dr. Brian Staiger on LinkedIn.

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