Allegra, known generically as fexofenadine hydrochloride, is an antihistamine used to alleviate symptoms associated with seasonal allergies and chronic idiopathic urticaria. It operates by inhibiting the natural effects of histamine within the body. Histamine can provoke symptoms such as sneezing, itching, watery eyes, and a runny nose. Notably, Allegra falls into the category of second-generation antihistamines, which are less likely to induce drowsiness compared to first-generation antihistamines.