"Rapid Acting – Non-Drowsy – Once a Day” Zyrtec is an antihistamine used to treat seasonal rhinitis and conjunctivitis (hayfever), pruitus (itching) of allergic origin, and insect bites. It is fast acting, (usually within 20 minutes of taking) non-sedating and its effect lasts for 24 hours. Active Ingredient Cetirizine hydrochloride 10mg Dosage For Adults and Children 6 years and over, 1 tablet (10mg) daily. Children 1-6 years half tablet (5mg) daily. A liquid formulation is avaliable (Zyrtec Solution) Caution Do not exceed a maximum dose of 20mg (2 tablets) a day. People with kidney problems, and pregnant or breast-feeding women should seek medical advice before taking this medicine. Although this medicine is unlikely to affect your ability to drive or operate machinery, a few people may be impaired and care should be taken. Pharmacy Only Medicine This website does not contain all the information available on this medicine. It does not take the place of talking to your doctor or pharmacist. All medicines have risks and benefits. If you have any questions about using this medicine please feel free to ask us.