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cetirizine vs fexofenadine

Side-by-side comparison of cetirizine and fexofenadine Data from FDA drug databases (Orange Book, NDC Directory, recalls, shortages) covering 20,000+ approved drugs, plus CMS pricing; see our methodology.

Drug Class
cetirizine Second-Generation Antihistamine
fexofenadine Second-Generation Antihistamine
Type
cetirizine Over-the-Counter
fexofenadine Over-the-Counter
Summary
cetirizine

Cetirizine (Zyrtec) is an antihistamine medicine. It helps relieve allergy symptoms.

fexofenadine

Fexofenadine (Allegra) is an antihistamine medicine. It helps reduce hives and relieve itching.

What It Treats
cetirizine

This medicine treats allergy symptoms. It can help with a runny nose, sneezing, and itchy, watery eyes. It also helps with itching of the nose or throat caused by hay fever or other upper respiratory allergies.

fexofenadine

This medicine treats hives and itching caused by hives. It will not stop hives or allergic skin reactions from happening. Talk to your doctor if you have questions about your condition.

How It Works
cetirizine

Cetirizine blocks histamine in your body. Histamine is a natural substance that causes allergy symptoms. By blocking it, cetirizine reduces these symptoms.

fexofenadine

Fexofenadine blocks histamine in your body. Histamine is a natural substance that causes allergy symptoms. By blocking histamine, fexofenadine reduces itching and hives.

Common Side Effects
cetirizine
  • Headache
  • Fatigue
fexofenadine
  • Headache
  • Fatigue
  • Nausea
FAERS Reports
cetirizine
  • The medicine did not work 12,977
  • Tiredness 12,862
  • Pain 12,124
  • Skin rash 9,771
  • Using the medicine for a condition it is not approved for 9,340
fexofenadine
  • Medicine not working 3,554
  • Headache 878
  • Tiredness 858
  • Feeling sick to your stomach 778
  • Itching 765
Serious Warnings
cetirizine

Ask a doctor before use if you have liver or kidney disease. Children under 2 years of age should ask a doctor before use.

fexofenadine

There are no boxed warnings for this medication.

Pregnancy
cetirizine

Ask a doctor if you are pregnant or breastfeeding before taking this medicine. It is not known if cetirizine will harm your unborn baby or pass into breast milk.

fexofenadine

It is not known if fexofenadine will harm your unborn baby. Talk to your doctor if you are pregnant or plan to become pregnant. It is also not known if fexofenadine passes into breast milk, so talk to your doctor if you are breastfeeding.

Also Compare — Nearby Drugs

How to Read This cetirizine vs fexofenadine Comparison

cetirizine is classified in the Second-Generation Antihistamine drug class, while fexofenadine sits within the Second-Generation Antihistamine class. Because both drugs share the same classification, they are often considered interchangeable in theory — but clinical outcomes rarely track that cleanly. Both drugs are available over the counter.

Adverse event totals above are pulled from the FDA's Adverse Event Reporting System (FAERS). For these top-ranked reactions alone, cetirizine has 57,074 submissions while fexofenadine has 6,833. Those figures reflect cumulative reporting volume — not per-patient risk — so older, widely dispensed drugs typically look worse on count alone. No direct interaction between these two drugs is listed in our FDA-derived dataset, though co-prescription still warrants pharmacist review. Serious warnings, pregnancy guidance, and contraindications can differ even when indications overlap.

A table cannot substitute for clinical judgment. Effectiveness, tolerability, drug-drug interactions with your other medications, kidney and liver function, pregnancy status, insurance formulary, and price all feed into a decision that only a licensed prescriber can make responsibly. Data here is sourced from FDA Structured Product Labels (SPL) and FAERS, both of which update as manufacturers and clinicians submit new information. This page is for educational purposes only, is not medical advice, and should not be used to self-switch between cetirizine and fexofenadine — always consult your physician or pharmacist first.

Important: This comparison is for informational purposes only. Drug effects vary between individuals. Always consult your doctor or pharmacist for personalized medical advice.