an alkaloid, CHNO, derived from certain Asiatic gymnosperms (family Ephedraceae) or synthesized, and used to relieve nasal congestion and asthma and to constrict certain blood vessels
See ephedrine in American Heritage Dictionary 4
(ĭ-fĕdˈrĭn, ĕfˈĭ-drēnˌ)
noun
A white, odorless, powdered or crystalline alkaloid, C10H15NO, isolated from shrubs of the genus Ephedra or made synthetically. It is used in the treatment of allergies and asthma.