Zyrtec (cetirizine), Claritin (loratadine), and Allegra (fexofenadine) are over-the-counter (OTC) antihistamines used to treat allergies. Overall, they work similarly well, but you may find that one works better for you. What do Zyrtec products treat? Zyrtec products are commonly used to treat allergy symptoms such as runny nose, itchy/watery eyes, sneezing, or an itchy nose or throat. The main active ingredient in. Cetirizine is a second-generation peripherally selective antihistamine used to treat allergic rhinitis (hay fever), dermatitis, urticaria (hives), and runny nose. [11]. It is taken by mouth. [12]. Effects generally begin within thirty minutes and last for about a day. [12]. Cetirizine is a second generation antihistamine that reduces the natural chemical histamine in the body. Histamine can produce symptoms of sneezing, itching, watery eyes, and runny nose. Cetirizine is used to treat cold or allergy symptoms such as sneezing, itching, watery eyes, or runny nose. Learn about cetirizine (Zyrtec) usage and dosing. Read the latest news and reviews about the drug as well as potential side effects and popular alternatives. Whether you need to know ZYRTEC ® dosages for adults or children, check out our dosing charts and FAQs for the ZYRTEC ® family of products, to find all the information you need. Zyrtec (cetirizine) is an over-the-counter antihistamine used to relieve allergy symptoms, including sneezing, itching, watery eyes, and a runny nose, and also reduces hives (urticaria). Zyrtec is usually taken once a day. From the 1 doctor and allergist recommended OTC allergy brand when it comes to oral antihistamines, Zyrtec Tablets contain 10 mg of Cetirizine HCl to help relieve indoor and outdoor allergy symptoms caused by dust, pet dander, and pollen. Zyrtec (cetirizine hydrochloride) is an antihistamine that treats symptoms, such as itching, runny nose, watery eyes, and sneezing from hay fever (allergic rhinitis) and other allergies, such as allergies to molds and dust mites. Overview: Cetirizine is an antihistamine that is taken to help treat allergy symptoms, such as a runny nose, itchy or watery eyes, sneezing, or an itchy nose or throat. It may also be used to.