Zirtek Allergy tablets 30 pack. Zirtek allergy tablets treat people suffering from hay fever (seasonal allergic rhinitis). Cetirizine dihydrochloride is the active ingredient of Zirtek Allergy. Zirtek Allergy is an antiallergic medication. In adults and children aged 6 years and above, Zirtek Allergy 10mg film- coated tablets are indicated for the relief of nasal and ocular symptoms of seasonal and perennial allergic rhinitis. It also for the relief of urticaria.