"Antihistamine"

One of a class of drugs used to fight histamine reactions by preventing special receptors in the body from binding to histamine during an allergic reaction. They are often used to treat symptoms of food allergies, such as hives and angioedema. Examples of over-the-counter antihistamines include Claritin (loratadine), Zyrtec (cetirizine), and Benadryl (diphenhydramine). Other antihistamines are available only by prescription; these include Clarinex (desloratidine), Allegra (fexofenadine), and Xyzal (levocetirizine).