Medical Definition of ephedra
1a capitalized : a large genus of jointed nearly leafless shrubs (family Gnetaceae) of dry or desert regions that have the leaves reduced to scales at the nodes and include some (especially E. sinica) that are a source of ephedrine—see ma huangb: any plant of the genus Ephedra
2: an extract of ma huang containing ephedrine and related alkaloids and used as a dietary supplement
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