Allergy & itch Dogs & Cats

Cetirizine (Zyrtec) for dogs and cats

Vets use it for itching from skin allergies, hives and insect bite reactions, and sometimes for respiratory allergy signs. [1]

Last reviewed: October 2026 · 2 sources · see sources

Quick answerCetirizine is a over the counter medicine for dogs and cats. It is an antihistamine. It blocks histamine, one of the chemicals that causes itching and swelling. The most common side effects: usually mild.

Key facts

Generic nameCetirizine
Common brand namesZyrtec, Reactine
Used inDogs & Cats
TypeAllergy & itch
Prescription?Over the counter (ask your vet first)
Typical US priceNot listed (no reliable public source)

What it's used for

Vets use it for itching from skin allergies, hives and insect bite reactions, and sometimes for respiratory allergy signs. [1]

How it works

It is an antihistamine. It blocks histamine, one of the chemicals that causes itching and swelling. [1]

Side effects and cautions

Common side effects: Usually mild. Rarely vomiting or drooling; sleepiness in small dogs and cats at higher doses. [1]

Use with care: Never use the combination product with pseudoephedrine (Zyrtec-D), which is dangerous for pets. Ask your vet before giving it, even though it is sold over the counter. [1]

Call your vet right away if your pet has trouble breathing, facial swelling, hives, collapse, or any side effect that is severe or getting worse.

About dosingDosing is your vet's call. We don't list doses because the right amount depends on your pet's weight, age, health and other medicines. Don't change a dose or stop a medicine without asking your vet, and never give a pet medicine meant for people unless your vet tells you to [2].

What it costs

We don't list a price for this one because we couldn't find a reliable public source. Ask your vet or pharmacy for a quote; prices depend on your pet's size, the dose and where you fill it.

Cetirizine FAQ

What is Cetirizine used for in dogs and cats?

Vets use it for itching from skin allergies, hives and insect bite reactions, and sometimes for respiratory allergy signs.

What are the side effects of Cetirizine?

Usually mild. Rarely vomiting or drooling; sleepiness in small dogs and cats at higher doses.

Does Cetirizine need a prescription?

Many forms are sold without a prescription. Still, check with your vet first. Pet doses and safe products are not the same as for people.

How much Cetirizine should I give my pet?

Only your veterinarian can tell you. The right dose depends on your pet's weight, health and other medicines, so we don't list doses. Never give a pet a medicine prescribed for a person or another animal without asking your vet.

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This page is general information for pet owners, not veterinary advice. Talk to your vet about your own pet.

Sources (2) — tap to show
  1. VCA Animal Hospitals – Cetirizine (veterinary drug handout)
  2. FDA – Frequently asked questions about animal drugs