Semen Vaccariae — Vaccaria hispanica (Mill.) Rauschert (family Caryophyllaceae), the dried ripe seed
Nature and flavour. Bitter, neutral. Liver and Stomach systems.
The name is a joke that the classical sources repeat with obvious relish: 王不留行 means the king does not let it linger, and the seed is described as one that moves and does not stay. It quickens the blood and frees the menses, promotes lactation, disperses swellings and settles pain, and it is recorded for amenorrhoea and difficult menstruation, for scanty or absent milk after childbirth, for breast abscess and painful swellings, and in the older literature for painful urinary difficulty. There is a second life for this seed that involves no swallowing at all: it is the object most commonly taped to ear points in auricular acupressure, chosen because it is small, round, hard and cheap — a physical pellet pressed against a point, not a medicine taken into the body. The traditional internal uses are recorded; the modern clinical evidence for them is limited and is not established.
性味归经。苦，平。归肝、胃经。
这味药的名字是个双关，古籍引述时显然乐在其中：王不留行即「王命亦不能留其行」，说的是它走而不守。功能活血通经、下乳、消肿止痛；记载用于经闭、经行不畅，产后乳少或乳汁不下，乳痈与肿痛，古文献亦载其治小便淋痛。这粒种子还有第二种完全不涉及内服的用途：它是耳穴贴压最常用的压丸 —— 只因它小而圆、硬且便宜 —— 那是压在穴位上的一粒实物，不是吃进身体的药。上述传统内服用途有文献记载，其现代临床证据有限，尚未被证实。
这是本草中孕期禁忌写得最明确的一味：它走血，古籍并将它与临产联系起来，故孕妇绝不可用。月经过多或有出血倾向者同样不宜；与抗凝药、抗血小板药同用须由执业医生判断，不是可以自行决定的事。下乳是多数人认识这味药的缘由，也正是最需要一句实话的用途：传统记载虽长，现代临床证据有限且尚未被证实；而乳汁不足有可以查证的常见原因 —— 含接、频次、甲状腺功能、胎盘残留 —— 不是一味种子能解决的，应当先查这些。哺乳期安全性未经现代研究确立：服药的是母亲，暴露的是婴儿。种子小而硬，对幼儿是呛噎隐患，家中存有耳穴压丸的尤其要注意。购买须认拉丁名：王不留行与麦蓝菜在流通中混用，已有其它种子冒充本品。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」。