For your worst allergy symptoms, nothing works faster or stronger than Allegra 24-Hour Adult Non-Drowsy Antihistamine Tablets. Allegra Tablets start working in one hour to give you round-the-clock relief from sneezing, runny nose, itchy and watery eyes and itchy nose or throat. One pill is all you need for 24-hour relief. Formulated with active ingredient fexofenadine, Allegra Non-Drowsy Allergy Medicine provides powerful relief from indoor and outdoor allergies, including seasonal allergies and pet allergies. Be ready for spring allergies, fall allergies, dog allergies and more. Stock up on Allegra 24-Hour Non-Drowsy Tablets for fast, effective allergy relief. Starts working in one hour, applies to the first dose only. Among single ingredient branded OTC oral antihistamines.