Source 出处 · Shanghan Lun · Doses are not given here: they are set by a licensed practitioner for the individual.
Safety. The Shanghan Lun introduces this with a word that has caused a great deal of commentary, pi yue, usually rendered as spleen constraint. The description is precise in an unexpected way: the patient's urine is frequent, yet the stool is hard and difficult, and the text says that in this case a purge should not be applied. The classical explanation is that the fluid has been diverted to the bladder, so the intestine is dry, and the reading is genuinely interesting because it explains a counterintuitive clinical observation - a person who is urinating a great deal and cannot open his bowels - by moving a single substance, fluid, from one place to another. Whether that mechanism is one a modern reader can accept as stated is another matter, and this entry is not going to settle it; what it will say is that the observation itself, frequent urination alongside hard stool, is real and worth noticing, and that the pair today points in several directions at once, including diabetes mellitus with polyuria, hypercalcaemia, and the diuretic effect of a medicine the patient has not mentioned.
The formula is the type case of the moistening purge, which is the branch of the purging method aimed at dryness rather than at heat: an oily seed to moisten, a small amount of the purgative to move, and qi-moving and descending pairs behind them. It is also, practically, the formula most people have heard of for constipation in older adults, in pregnancy and after childbirth, and in anyone recovering from illness, which is precisely why the safety half of this entry has to be written carefully rather than briefly.
Start with the red flags, because chronic constipation is a symptom with a long differential and a short list of things that must not be missed. New constipation beginning after middle age without an obvious cause is a reason to exclude colorectal cancer, and so is constipation accompanied by blood in the stool, unexplained weight loss, iron-deficiency anaemia, or a change in stool calibre that persists. Constipation also has a long medication list behind it - opioids first, then anticholinergics, calcium channel blockers, iron, some antacids, several antidepressants and antipsychotics, and over-the-counter antihistamines - and thyroid disease, hypercalcaemia, hypokalaemia, pregnancy, Parkinson's disease, spinal cord lesions and depression each appear on it. In older adults, the presentation that most reliably fools everyone is faecal impaction presenting as overflow diarrhoea, treated as diarrhoea, and made worse. And acute constipation with abdominal distension, vomiting and no passage of wind is obstruction until imaging says otherwise, which is a different and more urgent thing altogether.
On the materials. Hemp seed is Cannabis sativa seed, and it is worth being exact about what that does and does not mean. The seed is a food, is low in the psychoactive constituents that come from the flowering tops, and is used for its oil and protein; it is not a way to consume cannabis. What it can do, however, is produce a positive urine test for cannabinoid metabolites in some people, and that consequence falls on the person who ate it rather than on the plant. Peony brings the shao yao ambiguity that appears throughout this knowledge base: white peony root and red peony root are handled differently in practice and the name alone does not settle which is meant. Bitter orange brings p-synephrine, and extracts of it drew regulatory attention in the years after ephedra alkaloids left the supplement market in the United States, with cardiovascular adverse events reported for stimulant combinations; zhi shi and zhi ke are not the same item. Rhubarb is an anthraquinone stimulant laxative, and although it appears here in a supporting role, repeated use over time still brings dependence, fluid and potassium loss, and melanosis coli - which is the reason a moistening formula containing a stimulant is not automatically a gentle long-term option. Magnolia bark is the same conservation-sensitive Magnolia officinalis described in Xiao Cheng Qi Tang. Apricot kernel contains amygdalin, which releases cyanide on hydrolysis, and poisoning from it is reported repeatedly and disproportionately in children and with unprocessed kernels; the sweet kernel sold as food is a different item. Finally, laxatives of any kind are not a good idea in pregnancy or breastfeeding without a clinician's involvement, because the choice among them matters and because dehydration and electrolyte shifts do not stay contained to the person taking them.
The honest summary: this is the classic formula for the dry type of constipation, the old observation behind it is worth knowing, and the modern list behind constipation is long enough that starting with it rather than with the formula is the safer order.
《伤寒论》用了一个引来大量注释的词来介绍此方：脾约。它的描写有一种出人意料的精确：病人小便数，大便却硬而难解，而原文说这种情况不可用攻下。古典解释是津液被偏渗到膀胱，所以肠道失润；这个读法确实有意思，因为它用一个东西——津液——从一处移到另一处，解释了一个反直觉的临床观察：一个人小便很多，同时又解不出大便。至于这个机制现代读者能否照字面接受是另一回事，本条不打算裁决它；本站要说的是：那个观察本身——小便频数伴大便硬——是真的，值得留意，而且这一对症状今天同时指向好几个方向，其中包括多尿的糖尿病、高钙血症，以及某种患者没有提起的药物的利尿作用。
此方是润下法的样本方，而润下是攻下法里对准「燥」而不是对准「热」的那一支：一味油润的种子来润，少量泻下药来行，后面跟着行气与降气的一对。它在实践上也确实是多数人听说过的、用于老年人便秘、孕期产后便秘以及病后体弱者便秘的那一首方——这也正是为什么本条的安全部分必须写得仔细而不是简短。
先从红旗开始，因为慢性便秘是一个鉴别清单很长、而绝不能漏掉的条目很短的症状。中年后无明确原因新发的便秘，是排除结直肠癌的理由；便秘伴便血、不明原因的体重下降、缺铁性贫血，或粪便变细且持续存在，同样是。便秘背后还有一张长长的药物清单——阿片类居首，其后是抗胆碱药、钙通道阻滞剂、铁剂、某些抗酸药、若干抗抑郁药与抗精神病药，以及药店自购的抗组胺药；甲状腺疾病、高钙血症、低钾血症、妊娠、帕金森病、脊髓病变与抑郁也各在其列。在老年人身上最可靠地骗过所有人的，是表现为溢液性腹泻的粪便嵌塞：被当成腹泻处理，并被越弄越糟。而急性便秘伴腹胀、呕吐、不排气，在影像作出别的判定之前就是梗阻，那是一件不同而且更急的事。
单味药：火麻仁是大麻（Cannabis sativa）的种子，值得把「是什么、不是什么」说准。种子是食物，源自花穗的精神活性成分在它里面含量很低，人们用的是它的油与蛋白；它不是一种摄入大麻的方式。但它能做的一件事是：在部分人身上让尿液的 cannabinoid 代谢物检测呈阳性——而这个后果落在吃它的人身上，不落在植物身上。芍药带来本站处处出现的那个歧义：白芍与赤芍在实践中用法不同，光凭名字不能决定指的是哪一个。枳实带来对辛弗林问题；在麻黄碱类生物碱退出美国补充剂市场之后的那些年里，苦橙提取物受到监管关注，兴奋剂组合的心血管不良事件有报告；而枳实与枳壳不是同一味。大黄是蒽醌类刺激性泻药，虽然在这里只是辅佐，但反复久服仍会带来依赖、水与钾的丢失与结肠黑变病——这正是为什么一首含刺激性泻药的润下方并不自动等于温和的长期选择。厚朴就是小承气汤那条里提到的、来源敏感的 Magnolia officinalis。杏仁含苦杏仁苷，水解后释放氰化物，中毒报告反复出现，且以儿童与未经处理的种仁不成比例地居多；作为食物出售的甜杏仁是另一回事。最后：孕期与哺乳期在没有医生参与的情况下不宜使用任何一类泻药，因为选哪一种大有讲究，而脱水与电解质紊乱不会只停留在服药的人身上。
诚实的概括是：这是燥型便秘的经典方，它背后的那个旧观察值得知道，而便秘背后的现代清单长到足以让人——先从它、再从方子开始，是更安全的顺序。