Use in Countries Outside the U.S. Dose tables are based on U.S. products. Concentrations may vary in countries outside the U.S. Always check the concentration is the same before using this dose table. Detailed dosage guidelines and administration information for Zyrtec (cetirizine hydrochloride). Includes dose adjustments, warnings and precautions. 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. The typical cetirizine dose for allergies and hives is 5 to 10 milligrams (mg). Cetirizine comes in several oral forms and is usually taken once per day. Find patient medical information for Cetirizine (Zyrtec) on WebMD including its uses, side effects and safety, interactions, pictures, warnings, and user ratings Learn about the correct dosage for ZYRTEC® cetirizine products for both children & adults. Plus, find answers to common ZYRTEC® dosing-related questions. Read on for Zyrtec dosage information, including typical dosage, adjustments for health conditions, and what to do if you miss a dose. 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. The maximum recommended dose of Zyrtec (cetirizine) for adults is 10 mg once daily, taken as a single tablet. Proper dosing matters—taking more than recommended increases your risk of side effects without boosting effectiveness. Zyrtec (cetirizine) for allergic rhinitis and hives: 10 mg adult dosing, pediatric dose ranges, drowsiness notes, interactions, and country prices.