Can I Give My Cat Zyrtec?

Yes, with care
Cetirizine is commonly referenced for cats at published doses. Published guidance for cats: 5 mg per cat, every 24h. One of the better-tolerated antihistamines in cats.
Source: Veterinary Partner (VIN)
Get the exact range for your cat's weight

Skip it or ask a vet first if

Zyrtec-D / decongestant versionskidney disease

The safe habit

Confirm any medication decision with your veterinarian, who knows your cat's health history and other medications. VetDose shows published reference data, not prescriptions.

See also

Other antihistamine questions for cats