Experience Allegra, a premier rooftop bar in Scottsdale, AZ, with skyline views, poolside cabanas, cocktails, events and unforgettable sunsets. Book now! 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. 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. Detailed dosage guidelines and administration information for Allegra (fexofenadine hydrochloride). Includes dose adjustments, warnings and precautions. 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. 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. Get fast-acting relief from seasonal allergies and symptoms like a runny nose, sneezing, itchy, watery eyes, and itchy nose or throat. Allegra ® kicks in within just one hour with 0% brain interference from drowsiness—that's right, it doesn't enter your brain and leave you feeling groggy. 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.