Fexofenadine hydrochloride (marque include Allegra® & Telfast®) is an antihistamine drug used in the treatment of hayfever and similar allergy symptoms. It was developed as a successor of & option to terfenadine, an antihistamine with possibly deadly contraindications.

History
Fexofenadine was developed by Hoechst Marion Roussel (now section of Aventis) and approved per FDA in 1996. Since that period, it has achieved blockbuster drug status by owning spherical sales of $1.87B USD inside 2004 (with $1.49B USD from either a United States).