Use these zyrtec dosage guides for infants and children younger than 12 years old. Zyrtec is used in adults and children to treat cold or allergy symptoms such as sneezing, itching, watery eyes, or runny nose. Zyrtec is also used to treat itching and swelling caused by chronic urticaria (hives). The recommended initial dose of ZYRTEC is 5 mg or 10 mg per day in adults and children 12 years and older, depending on symptom severity. Most patients in clinical trials started at 10 mg. ZYRTEC is given as a single daily dose. Each 5 mL of this allergy syrup contains 5 mg of cetirizine HCl antihistamine to help treat allergy symptoms such as runny nose, sneezing, and itchy nose and throat. Available in both grape or bubble gum flavors, Children’s ZYRTEC ® Syrup is suitable for children and toddlers ages 2 years and up. Boston Children's Health Physicians Cetirizine Dosing Chart Antihistamine Dosing for Allergies and Hives: Once-daily dosing unless noted. Use only one antihistamine at a time. Always double-check concentration on the bottle. Detailed dosage guidelines and administration information for Zyrtec (cetirizine hydrochloride). Includes dose adjustments, warnings and precautions. Use this dosage chart to determine the correct dosage of ZYRTEC ® for adults. Remember to always read the label on the packaging & follow directions for use carefully before you take a dose. Read on for Zyrtec dosage information, including typical dosage, adjustments for health conditions, and what to do if you miss a dose. Detailed Cetirizine dosage information for adults, the elderly and children. Includes dosages for Allergic Rhinitis and Urticaria; plus renal, liver and dialysis adjustments. Giving your child Zyrtec? Find the recommended dose to safely give your child based on weight and age with the St. Louis Children's Hospital infant and child medication dosage table.