Zyrtec (Cetirizine) Dosage for Dogs

The standard dose of Zyrtec (cetirizine) for dogs is 1 mg per kilogram of body weight, given once daily. For example, a 10 kg (22 lb) dog would receive one 10 mg tablet per day. Smaller dogs under 5 kg may receive a half tablet of the 5 mg size.

Yes, Zyrtec is commonly given daily for ongoing allergy management in dogs. Its once-daily dosing makes it convenient for long-term use. However, consult your veterinarian before starting any long-term medication to rule out underlying conditions that may need different treatment.

Plain Zyrtec (cetirizine) is generally considered safe for dogs at the recommended dose. However, you must never use Zyrtec-D, which contains pseudoephedrine — a decongestant that is toxic to dogs and can cause life-threatening symptoms including high blood pressure, seizures, and death.

It is generally not recommended to give both Zyrtec and Benadryl at the same time without veterinary guidance, as both are antihistamines and combining them increases the risk of excessive sedation and other side effects. Your vet may recommend switching between them or using one at a time.

Zyrtec typically begins working within 1-2 hours of administration in dogs. Full effects may take a few days of consistent daily dosing to become apparent, especially for chronic allergy symptoms like atopic dermatitis.