What is Allegra? Allegra (fexofenadine) is an antihistamine used to treat allergy symptoms, including sneezing, itching, watery eyes, and a runny nose in adults and children. Overview: Fexofenadine 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. Common side effects may. Fexofenadine (Allegra) is an antihistamine that treats and prevents allergy symptoms. It blocks histamine to reduce your symptoms. Allegra 120mg Tablet is an anti-allergy medicine. It is used to treat allergic rhinitis and chronic idiopathic urticaria. It relieves symptoms such as sneezing, runny nose, nasal congestion, itching, watery eyes, and hives. It works by blocking histamine, a substance that triggers allergic symptoms. Allegra 120mg Tablet is usually taken before. Detailed dosage guidelines and administration information for Allegra (fexofenadine hydrochloride). Includes dose adjustments, warnings and precautions. While some other oral antihistamines may cause you to be drowsy, Allegra® won't. Fexofenadine, the active ingredient in Allegra ®, provides non-drowsy allergy relief with 0% brain interference, relieving allergy symptoms like sneezing, runny nose and itchy eyes. Allegra (Fexofenadine Hcl) may treat allergy, side effects, dosage, drug interactions, warnings, patient labeling, reviews, and related medications including drug comparison. It is a common over-the-counter medication available under many brand names (including Allegra), as well as a generic drug. [11] Therapeutically, fexofenadine is a selective peripheral H 1 blocker. Want fast, non-drowsy allergy relief? Allegra helps relieve your toughest allergy symptoms, without the drowsy effect, empowering you to live life fully*, everyday. Allegra products are commonly used to treat allergy symptoms such as runny nose, sneezing, itchy/watery eyes, itchy nose or throat, hives, nasal congestion, and sinus pressure. The main active.