What is cetirizine. Cetirizine or cetirizine hydrochloride (cetirizine HCL) is a non-drowsy antihistamine medicine that relieves the symptoms of allergies by blocking the effects of the chemical histamine in your body. Cetirizine hydrochloride is a white, crystalline powder and is water soluble. Zyrtec Tablets are formulated as white, film-coated, rounded-off rectangular shaped tablets for oral administration and are available in 5 and 10 mg strengths. H 1 antagonists, also called H 1 blockers, are a class of medications that block the action of histamine at the H 1 receptor, helping to relieve allergic reactions. Benadryl (diphenhydramine) is a brand-name, over-the-counter medication that’s classified as an antihistamine. It’s used to help relieve symptoms of hay fever (seasonal allergies), other. Best Antihistamine for hives review: Zyrtec vs Allegra Benadryl Claritin etc. How to choose Diphenhydramine / Loratadine / Cetirizine / Fexofenadine drugs? Zyrtec (cetirizine) is an antihistamine in the class of drugs referred to as second-generation antihistamines. Antihistamines work by blocking histamines, chemical signals released by a type of cell in the immune system (mast cells) in order to alert other cells about a potential invader. Cetirizine hydrochloride is a white, crystalline powder and is water soluble. Cetirizine hydrochloride syrup is a colorless to slightly yellow syrup containing Cetirizine hydrochloride at a concentration of 1 mg/mL (5 mg/5 mL) for oral administration. Compare prices and find coupons for Zyrtec (Cetirizine) at more than 60,000 US pharmacies. Save up to 80% instantly! Compare prices and find coupons for Cetirizine (Generic Zyrtec) at more than 60,000 US pharmacies. Save up to 80% instantly! Zyrtec is the brand name of cetirizine, an over-the-counter (OTC) antihistamine used to treat cold and allergy symptoms such as sneezing, itching, watery eyes, or runny nose.