Zyrtec is used for the treatment of allergies. - It is an antihistamine medication that stops the natural secretion of histamine in the body. - It reduces allergy symptoms such as increased watery eyes and cold and runny nose. - It may be easier for children to take Zyrtec syrup than it is for tablets. - Children's dose: From 6 months to 2 years: 5 drops once daily. From 2 to 5 years: 10 drops once daily. - Take Zyrtec Oral Drops with or without food, once a day, preferably in the evening or night as it may cause slight drowsiness.