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Cetirizine for Pets: Effective Allergy & Itch Relief Antihistamine

Published on September 10th, 2024
Updated on October 15th, 2025
Cetirizine is an antihistamine medication most commonly used as an adjunctive treatment for itching associated with allergies. It is often used extra-label in veterinary medicine.
Cetirizine

Summary

Used For:

Itching associated with allergies, allergic reactions, blocking histamine release in mast cell tumor

Brands:

Zyrtec®, Piriteze®

Species:

Cats, Dogs, Horses

Drug type:

Antihistamine

Prescription required:

No

Pregnancy and lactation:

Likely safe for pregnant or lactating animals, but consult a veterinarian before use

Side effects:

Vomiting, hypersalivation (drooling), drowsiness
 

General description

Cetirizine is a second generation antihistamine medication that blocks the release of histamine, which is a substance that causes inflammation, skin redness, and swelling, often leading to itching. For this reason, cetirizine is typically used as an adjunctive treatment in the management of itching associated with allergies, allergic reactions, and blocking histamine release due to mast cell tumors. It is often used extra-label in veterinary medicine.

Uses

Itching associated with allergies, allergic reactions, and blocking histamine release in mast cell tumors

How it works

Cetirizine works by blocking H1 (histamine) receptors and decreasing the histamine release from basophils (a type of white blood cell) in some species.

Dosage

Dogs: 0.5-1 milligrams per kilogram of body weight by mouth once daily Cats: 5 milligrams per cat by mouth once daily Horses: 0.2-0.4 milligrams per kilogram of body weight by mouth every 12-24 hours

Forms

Cetirizine HCl coated and chewable tablets for oral use are available in 5 milligram & 10 milligram sizes. Cetirizine HCl liquid suspension for oral use is available in a 1 milligram per milliliter concentration.

Storage information & handling

Keep in the original package or a childproof container at room temperature, out of the reach of pets and children.

What results can I expect?

Improvement in itching associated with allergies, resolution of allergic reaction, and management of histamine release from mast cell tumor.

Missed Dosage

If a dose is missed, give the dose as soon as possible. If it is almost time for the next dose, skip the missed dose and give the next dose at the regularly scheduled time. Do not give two doses at once.

Overdose / acute toxicity

If an overdose is known or suspected, seek veterinary attention immediately. Signs of an overdose may include hyperactivity, vomiting, lethargy, panting, pupil dilation, and an increased heart rate.

Side effects

*Vomiting *Hypersalivation (drooling) *Drowsiness at higher doses

Contraindications

*Use with caution in patients with liver or kidney dysfunction *Use with caution in patients with previous sensitivity

Drug interactions

Medications that depress the central nervous system may interact with cetirizine. Discuss all medications and supplements with your veterinarian before administering any new medication.

Precaution

Due to limited experience in veterinary medicine, caution should be exercised with use in patients with existing liver or kidney disease, and reduced dosages are recommended.

Sources

Plumb’s Veterinary Drug Handbook

Disclaimer
The information contained on this page is for educational purposes only. This medication should only be given under the advice of a veterinarian who has examined your pet under the laws applicable to your state of residence.

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