A Guide to Cetirizine - Zyrtec Generic Option

The Easiest Way to Help Keep Your Pet's Allergies at Bay

By Sam Bourne.

  • General Allergies
  • Pruritus (Scratching/Itching)

indications for Cetirizine

Cetirizine, better known as Zyrtec, is an antihistamine that can help control histamine-mediated pruritus by blocking the H-1 receptor, thereby inhibiting the inflammatory response triggered by the histamine. In layman's terms, Cetirizine helps to reduce any allergen-related (histamine-mediated) irritation (pruritus) by stopping the allergen pods (histamine) from reaching their docking stations (H-1 receptors), thereby preventing your body from sounding the allergy alarm (coughing, itching, and sneezing).

Since Cetirizine is a drug primarily intended for human use, and since there is no veterinarian-approved equivalent, Cetirizine for dogs and cats is considered an extra-label drug, or a drug being used outside its realm of approved use, even though it is commonly prescribed for pets by veterinarians.


Dogs or cats with hypersensitivity to antihistamines should not be given Cetirizine.

Pets with renal or liver problems should be carefully monitored and have their dosages regulated based on the severity of their condition.

Cetirizine has not been proven safe to use in dogs or cats that may be pregnant or nursing.


Cetirizine comes in tablet form and should be taken orally once a day. For dogs, dosage is based off of their overall weight, the ratio being 1 mg of Cetirizine per kilogram.Cats should be given somewhere between 2.5 - 5 mg of Cetirizine, never exceeding the 5 mg cap.

These dosages are only an educated estimate and a licensed vet should be consulted before starting any new drug regimen.

Brand/Generic equivalents


Side Effects

In some cases, vomiting or hypersalivation has occurred after starting on Cetirizine. In some small dogs taking higher dosages, drowsiness has been reported.

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Cetirizine at a glance

  • 1For dogs and cats
  • 2An antihistamine
  • 3A tablet to be taken orally
  • 4Helps alleviate allergy symptoms

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