Zirtek Cetirizine Oral Solution 1mg/ml (100ml). Cetirizine is the active ingredient of Zirtek.. Zirtek is an antiallergic, antihistamine medication.. In adults and children aged 2 years and above, Zirtek 1 mg/ml oral solution is indicated. for the relief of nasal and ocular symptoms of seasonal and perennial allergic rhinitis. for the relief of urticaria
