Foster And Thrive, 24 Hour Allergy Relief Fexofenadine Hci Usp, 180 Mg, 70 TabsProduct Description 24 hour allergy relief fexofenadine HCL is a non prescription antihistamine used to provide long lasting relief from allergy symptoms. The active ingredient, fexofenadine hydrochloride, is a second generation antihistamine that helps to reduce the effects of histamine, a substance in the body that causes allergic reactions. Product Benefits Temporarily Relieves These Symptoms Due To Hay Fever Or Other Upper Respiratory Allergies.