What it is: Cetirizine (Zyrtec)—second-generation antihistamine for hay fever and hives. Typical dose: 10 mg once daily; 5 mg may suffice for mild symptoms or kidney impairment. Q: What is Zyrtec 24 Hour Allergy Relief Tablets? A: Zyrtec 24 Hour Allergy Relief Tablets is an over-the-counter medication for year-round allergy relief, known to be the number one allergist-recommended brand of oral antihistamines. 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. 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. 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. Zyrtec is used in adults and children to treat cold or allergy symptoms such as sneezing, itching, watery eyes, or runny nose. Zyrtec is also used to treat itching and swelling caused by chronic urticaria (hives). Zyrtec (cetirizine) provides rapid symptom relief for seasonal/perennial allergic rhinitis and hives. It is generally well tolerated; however, mild drowsiness can occur in some patients compared with fexofenadine or loratadine. 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. 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. 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.