Herba Lycopi — Lycopus lucidus Turcz. var. hirtus Regel (family Lamiaceae), the dried aerial parts
Nature and flavour. Bitter and acrid, slightly warm. Liver and Spleen systems.
A marsh plant used as a blood mover, and one of the few in this group that the texts also credit with moving water. It quickens the blood, regulates the menses and dispels stasis, promotes urination and reduces swelling, and it is recorded for irregular or suppressed menstruation, for abdominal pain after childbirth attributed to retained stasis, and for oedema and difficult urination. The combination is the point: where the classical description is of stasis and water together, this is the herb that gets named. Its reputation in Western herbal literature is a separate matter and is addressed in the caution below. The traditional uses are recorded; the modern clinical evidence for them is limited and is not established.
性味归经。苦、辛，微温。归肝、脾经。
一味生于湿地的活血药，也是本批中少数被古籍同时认为能行水的一味。功能活血调经、祛瘀、利水消肿；记载用于月经不调、经闭，产后瘀滞所致的腹痛，以及水肿与小便不利。妙处正在这个组合：凡古典描述为瘀与水并见者，古籍点名的往往就是它。它在西方草药文献中的声誉是另一回事，写在下面提示里。上述传统用途有文献记载，其现代临床证据有限，尚未被证实。
两个名字相近的品种不能互替：中医的泽兰是 Lycopus（地笋属），而佩兰是 Eupatorium fortunei，二者传统用途不同、安全性也不同。购买须认拉丁名。作为活血药，孕期禁用；月经过多及合用抗凝、抗血小板药时同样谨慎。另有一条来自西方草药文献的顾虑：其近缘的 Lycopus 属植物（欧美所称 bugleweed）在传统上被认为作用于甲状腺，现代西方资料将其列为甲状腺功能减退、孕期与哺乳期应回避的品种。那是从中国本草不同的另一套传统，但属是同一个；有甲状腺疾病或正在服用甲状腺药物者，未经其主治医生知情不得使用。水肿是有原因的 —— 心、肾、肝、静脉 —— 一味利尿草药解决不了，这些需要诊断。任何使用都须在合格执业者监督下进行；本页刻意不回答「该用多少」。