Radix Ephedrae — the dried root and rhizome of Ephedra sinica Stapf, E. intermedia Schrenk et C.A.Mey. or E. equisetina Bunge (family Ephedraceae). Not the stem: the stem is a different drug (麻黄) with the opposite traditional direction.
Nature and flavour. Sweet and astringent, neutral. Heart and Lung systems.
A teaching example of how much the part of the plant matters. The stem of Ephedra is the classical diaphoretic that drives sweating outward; the root is the classical drug for arresting it. The sources record the root for spontaneous sweating, for night sweating, and for the sweating of deficiency states, and this opposition — one plant, two directions — is repeated across the classical texts. Modern phytochemistry supports the direction of the distinction in a general way: the root carries a different alkaloid profile and a lower total alkaloid content than the aerial stem. That is a relative statement about chemistry, not a statement that the root is inert, and it should not be read as a safety guarantee.
性味归经。甘、涩，平。归心、肺经。
说明「药用部位差多少」的教科书式例子。麻黄的茎是古典发汗药，把汗往外推；麻黄的根是古典止汗药。文献记载其根用于自汗、盗汗与虚证之汗，这种「同一株植物、两个方向」的对举在古典文本里反复出现。现代植物化学大体支持这种区分的方向：根部所含生物碱谱与地上茎不同，总生物碱含量也较低。这是关于化学组成的相对陈述，不等于说根是惰性的，更不能当作安全保证来读。
麻黄属在全球多地受法律管制，这是首先要写的话。麻黄碱与其它麻黄属生物碱属于受管制物质：美国 FDA 于 2004 年终止麻黄碱类膳食补充剂的销售，麻黄属原材料仍属 DEA 管制与 FDA 限制的商品；在中国，麻黄属植物材料与麻黄碱类制剂同样纳入易制毒化学品管理。因此跨境携带麻黄属材料不是小事。高血压、心脏病或心律失常、甲状腺功能亢进、青光眼、前列腺肥大伴排尿犹豫、失眠者，不应服用任何形式的麻黄属材料，根也包括在内；与单胺氧化酶抑制剂、兴奋剂、减充血剂、咖啡因及降压药的相互作用风险是真实的。绝不可把它写成或当作兴奋剂、减重用品来卖——那正是导致脑卒中、心肌梗死与猝死个案报告的用途，且并非传统用法。孕期、哺乳期与儿童不宜。