Ephedrine is an alkaloid that was isolated from the plantEphedra vulgarisby Nagai in 1887 and rediscovered by Chen in 1923. Decoctions ofEphedra vulgarishave been used in China for five thousand years for diaphoretic and antipyretic purposes and as a sedative in cough. At the time of the original discovery of the alkaloid, the attention of the investigators was focused mainly on its mydriatic properties. To Chen1belongs the honor of working out the complete pharmacology of ephedrine, which was found to be a sympathomimetic drug closely allied in its chemical constitution and physiologic action to epinephrine. Chemically, ephedrine differs from epinephrine in that it does not contain a phenolic hydroxyl group, but has an extra methyl radical which accounts for its more persistent effects and greater stability, permitting oral administration of the drug and sterilization of its solutions by boiling. The physiologic effects of ephedrine are