Zyrtec is an antihistamine medication containing 10mg of Cetirizine dihydrochloride per tablet. It provides 24-hour relief from allergy symptoms like sneezing, runny nose, watery eyes, and itching caused by hay fever and other upper respiratory allergies. Each pack contains 20 film-coated tablets. Zyrtec is a prescription medication that should be taken as directed by your healthcare provider. The typical adult dosage is one 10mg tablet daily. This medication may cause drowsiness. Do not exceed the recommended dose. Consult your doctor before use if pregnant, breastfeeding, or have kidney or liver problems.