To the mother of the 17mo old...
My son was given zyrtec from about 6mos old until about a week ago. he's now 22mos old and weighs enough to start claritin. He also started singular at about a 1yr old. We have only switched to claritin because the zyrtec wasn't working as well as the dr thinks it should be. We didn't have any allergic reactions or changes in behavior with either medications. He has horrible allergies that make it hard for him to breath and he has about 2-3 ear infections a month so we do all we can to keep him free from all allergens. We are going to start allergy testing soon. I hope this helps
From
http://www.pfizer.com/files/products/uspi_zyrtec.pdf
Children 6 to 11 Years: The recommended initial dose of ZYRTEC in children aged 6 to
11 years is 5 mg or 10 mg once daily depending on symptom severity. The time of administration
may be varied to suit individual patient needs.
Children 2 to 5 Years: 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.
Children 6 months to <2 years: The recommended dose of ZYRTEC syrup in children 6
months to 23 months of age is 2.5 mg (½ teaspoon) once daily. The dose in children 12 to 23
months of age can be increased to a maximum dose of 5 mg per day, given as ½ teaspoon
(2.5 mg) every 12 hours. Syrup is recommended for children under the age of 2 years.