Yes. You can. There is a chart on the side of the bottle - follow the directions

Yes you can

Yes, long acting antihistamines such as Zyrtec and Claritin can safely be used for very young children. I suggest discussing your specific dosing questions with your pediatrician - they can instruct you on the proper doses for general allergic rhinitis symptoms and also for use in acute more severe allergic reactions such as food anaphylaxis.

Yes. Zyrtec (or its generic “cetirizine”) has a pediatric formulation. Depending on the age of the child, the dose varies from 2.5 to 10 mg per day.

Yes, and the recommended initial dose of ZYRTEC in children aged 2 to 5 years is 2.5 mg (½ teaspoon) syrup once daily. The dosage in this age group can be increased to a maximum dose of 5 mg per day given as 1 teaspoon syrup once a day or one ½ teaspoon syrup given every 12 hours, or one 5 mg chewable tablet once a day.

Safe dose for 2 to 6 years of age is 2.5 ml of Zyrtec for rhinitis, itch due to atopic dermatitis (eczema) and hives. Allergic reaction is a term generally used for anaphylaxis - which can be life-threatening. But commonly, people use allergic reaction meds for skin rashes, respiratory symptoms of rhinitis, itch, and hives.