Zyrtec, or cetirizine, is an antihistamine medication available over the counter to treat allergies and hives. In infants, Zyrtec is the only Food and Drug Administration-approved medication to treat perennial allergic rhinitis and chronic urticaria. Do not give Zyrtec or any other allergy medication to your infant without specific instructions to do so by your baby's pediatrician. According to McNeil-PPC, Zyrtec is no longer available by prescription.
Allergies affect as many as 50 million people in the United States, many of them infants and young children, according to the American Academy of Allergy Asthma and Immunology. Allergies can cause significant discomfort and affect eating, sleeping and quality of life. Zyrtec is the only medication approved by the FDA to treat both indoor and outdoor allergies in infants as young as 6 months old. Zyrtec can also be preferable to older generation antihistamines, such as diphenhydramine or clemastine because it tends to cause fewer side effects.
Zyrtec treats the symptoms of allergies by reducing the amount of histamine in the body. During an allergic reaction, an allergen that enters the body through inhalation or other means is recognized by the body as an intruder. The body then releases special white blood cells, called mast cells, to attack the allergen. During this attack, histamine is released from the mast cells, causing the mucus membranes to swell and secrete mucus. Symptoms associated with high levels of circulating histamine include sneezing, runny nose, watery eyes and chronic urticaria. Zyrtec blocks histamine's effects on the body.
The manufacturer's recommended dose of Zyrtec in children age 6 months to 23 months is 2.5 mg, or 1/2 teaspoon, of syrup. Give your infant Zyrtec with or without food, or as instructed by your baby's pediatrician. Use the measuring cup provided with the product to ensure an accurate dose. Too much Zyrtec can be harmful to health. In most cases, Zyrtec should be taken once each day at the same time each day. If using Zyrtec to treat hives in your infant, consult a doctor if the symptoms do not improve within three days of beginning treatment or if symptoms worsen while taking the medication.
Zyrtec can cause a number of common side effects during use. These side effects, which include dry mouth, dizziness, sore throat, cough, constipation, nausea and headache, might disappear with continued treatment. More serious side effects of Zyrtec include a rapid, uneven or pounding heartbeat, shaking, insomnia, weakness, hyperactivity, confusion, vision problems, or decreased frequency of urination. In some infants, Zyrtec can cause symptoms of an allergic reaction, including breathing problems, hives or swelling of the lips, face, throat or tongue. Symptoms of overdose include nervousness and restlessness followed by drowsiness.
Although Zyrtec is less likely to cause drowsiness than some other allergy medications, sleepiness is possible in infants, especially when the medication is taken at high doses. Drugs.com notes that taking Zyrtec in conjunction with other medications that cause drowsiness, such as cold medicines or anti-seizure drugs, can increase this effect.