How can i reduce my mother's allergy to kittens? should she be on zyrtec (cetirizine) every day?

Tricky: Cat allergy is tough. Cats are very potent sensitizers of the airways. Antihistamines are ok for sneezing and itchy, watery eyes but nasal steroid sprays give much better relief of nasal symptoms. Try washing the cat, keeping it out of her bedroom, and getting a hepa air filter for the bedroom. If these aren't helping or there are any chest symptoms, it's time to see the allergist.