Medical Disclaimer
Last reviewed: June 2026
Important Warning
This calculator is for educational and informational purposes only and is not a substitute for professional veterinary care. Never give your dog Zyrtec-D (which contains pseudoephedrine) or any product containing xylitol — both can be fatal to dogs. Always consult your veterinarian before giving cetirizine to your dog.
Not Veterinary Advice
The Zyrtec for Dogs Calculator and all information on this website are provided for general educational purposes only and are not intended to be a substitute for professional veterinary advice, diagnosis, or treatment. Only a veterinarian who has examined your dog can recommend whether cetirizine is appropriate and at what dose.
Off-Label Human Medicine
Cetirizine (Zyrtec) is an over-the-counter human medication. Its use in dogs is "off-label" — meaning it is not specifically approved for dogs and is used at a veterinarian's discretion. Doses, frequency, and suitability vary by dog, and your veterinarian's guidance always takes priority over any estimate shown here.
Never Use Combination or Xylitol Products
Only plain, single-ingredient cetirizine is appropriate. Decongestant combination products such as Zyrtec-D contain pseudoephedrine, which is highly toxic to dogs. Some dissolving tablets, chewables, and liquids contain xylitol, which can cause life-threatening low blood sugar and liver failure. Always read the full ingredient list. In a suspected poisoning, call the ASPCA Animal Poison Control Center at 888-426-4435.
Individual Variation
The weight-based estimate (about 0.5 mg/lb, or 1 mg/kg) is a general guideline. Your veterinarian may adjust dosing based on your dog's age, weight, overall health, other medications, and response to treatment.
Accuracy of Information
While we strive to provide accurate, up-to-date information based on recognized veterinary sources, we make no warranty about its completeness or reliability, and it may not reflect your veterinarian's specific recommendations.
Limitation of Liability
By using this calculator you agree that we are not liable for any harm arising from use of or reliance on the information provided, incorrect use of the calculator, or failure to seek professional veterinary care.
Authoritative Sources
Merck Veterinary Manual · PetMD — Cetirizine for Dogs · ASPCA Animal Poison Control