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cetirizine vs loratadine

Side-by-side comparison of cetirizine and loratadine 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
loratadine Second-Generation Antihistamine
Type
cetirizine Over-the-Counter
loratadine Over-the-Counter
Summary
cetirizine

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

loratadine

Loratadine is an antihistamine medicine. It helps relieve allergy symptoms.

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.

loratadine

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

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.

loratadine

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

Common Side Effects
cetirizine
  • Headache
  • Fatigue
loratadine
  • Headache
  • Fatigue
  • Drowsiness
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
loratadine
  • Medicine not working 12,662
  • Tiredness 6,401
  • Feeling sick to your stomach 5,688
  • Head pain 5,182
  • Difficulty breathing 4,656
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.

loratadine

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.

loratadine

If you are pregnant or breastfeeding, talk to your doctor before taking loratadine. They can help you weigh the risks and benefits.

Also Compare — Nearby Drugs

How to Read This cetirizine vs loratadine Comparison

cetirizine is classified in the Second-Generation Antihistamine drug class, while loratadine 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 loratadine has 34,589. 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 loratadine — 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.