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.

2 min read Updated Jun 2026 Read by 4,751 people
Can You Take Zyrtec-D Or Allegra-D With Amoxicillin?
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Christina asked

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

Jan 19, 2023
The quick answer
  • It is generally safe to take Zyrtec-D or Allegra-D with amoxicillin as there are no known interactions between these medications.
  • These combination products contain an antihistamine to help with sneezing, itching, and runny nose, plus a decongestant to relieve nasal congestion from infection or allergies.
  • You should only take one antihistamine/decongestant combination at a time, either Zyrtec-D or Allegra-D, not both together.
A quick summary of Dr. Brian Staiger, PharmD's full answer below, condensed by AI from that answer only (not from any outside source). The pharmacist's answer is the source of record.

Answer

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 out again anytime.

References & sources
  1. Cetirizine Monograph — PubChem
  2. Fexofenadine Monograph — PubChem
  3. Pseudoephedrine Monograph — PubChem
  4. Amoxicillin Monograph — PubChem
Glossary — Terms in This Answer
Antihistamine
A medication that blocks the effects of histamine to relieve allergy symptoms like sneezing, itching, and runny nose.
Decongestant
A medication that helps relieve nasal congestion caused by infections or allergies.
Pseudoephedrine
A decongestant ingredient used to reduce nasal congestion.
Histamine
A chemical released by the body's cells when exposed to allergens that causes allergy symptoms.
Antibiotic
A medication used to kill bacteria and treat bacterial infections.
Amoxicillin
An antibiotic derived from penicillin that is used to treat bacterial infections like sinus infections.
Second-generation antihistamines
A newer type of antihistamine that causes less drowsiness than older first-generation antihistamines.
Mast cells
Cell types in the body that store and release histamine when exposed to allergens.
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Dr. Brian Staiger, PharmD
About the pharmacist

Dr. Brian Staiger, PharmD

Clinical Pharmacy

Doctor of Pharmacy, board certified clinical pharmacist (BCPS), American Herbalist Guild, Medication Therapy Management certified

Brian Staiger, PharmD, BCPS, is a licensed pharmacist with more than 13 years of experience across retail pharmacy, clinical pharmacy, medication safety, pharmacy program development, and healthcare administration. He is the founder of HelloPharmacist.com, where he helps patients...

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