Source 出处 · Wenbing Tiaobian · Doses are not given here: they are set by a licensed practitioner for the individual.
Safety. Zeng Ye Cheng Qi Tang is Zeng Ye Tang with two purgatives added. The three sweet, moistening roots — 玄参, 麦冬, 细生地 — are the fluid-increasing half; 大黄 and 芒硝 are the purging half. The classical image is 增水行舟: raise the water and the boat floats. It is one of the more self-explanatory names in the tradition, and the indication it is recorded for is also the sharpest thing about it.
That indication is 下之不通 — the person has already been purged, and it did not work. Today, having already purged without result is a reason to stop and look rather than to escalate. The things that make a bowel fail to move after a purge include mechanical obstruction from tumour, adhesion, volvulus or hernia, faecal impaction with overflow diarrhoea that mimics the opposite problem, toxic megacolon, paralytic ileus after surgery or from medicine, and severe colonic stricture from inflammatory bowel disease or ischaemia. Adding a stronger stimulant purgative to a mechanical obstruction is the wrong direction, and it is one of the few places in herbal literature where a classical indication translates directly into a modern imaging request.
Even where the cause is ordinary constipation, the modern sequence differs. New-onset constipation after roughly fifty is an indication for colorectal cancer screening; the rest of the list is hypothyroidism, hypercalcaemia, diabetes, Parkinson's disease, depression, immobility, low fluid and fibre intake, irritable bowel syndrome, and medicine — opioids, anticholinergics, calcium channel blockers, iron, and some antidepressants among them. One item on that list is an emergency rather than a differential: constipation with back pain, saddle anaesthesia, or new bladder or bowel incontinence can be cord or cauda equina compression, and that is a same-day scan.
The two added ingredients each carry their own weight. 大黄 is rhubarb, an anthraquinone stimulant laxative; this class is no longer first-line for ordinary constipation, long-term use is associated with melanosis coli and with potassium loss, and European regulators have restricted anthraquinone laxatives to short-term use for that reason. Rhubarb root also contains tannins, which is why a purge with it can be followed by the opposite problem. 芒硝 is hydrated sodium sulphate — Glauber's salt — and that is a genuine sodium load, relevant in heart failure, hypertension and kidney disease; osmotic purgatives and bowel preparations have caused acute kidney injury and severe electrolyte disturbance, which is the mechanism to take seriously rather than the purgation itself. 芒硝 is also not 硝石, which is potassium nitrate, saltpetre.
One point of classification is worth keeping: the three-ingredient version without the purgatives is Zeng Ye Tang, and it is already in this library. The difference between the two is exactly the two ingredients that make this one a purgative formula rather than a moistening one. This entry documents the composition and the reasoning. It is not guidance for anyone with a bowel that has stopped working.
增液承气汤就是**增液汤再加两味攻下药**。三味甘润的根 —— 玄参、麦冬、细生地 —— 是「增液」的一半，大黄与芒硝是「承气」的一半。古典取象是**增水行舟**：水涨起来，船自己就走了。这是传统里字面最清楚的方名之一，而它被记录的适应症，恰恰是全方最值得说的一点。
这个适应症是**下之不通** —— 已经下过了，没通。今天，**已经攻下而无效是停下来检查的理由，而不是加大的理由**。攻下之后仍不通的原因包括：肿瘤、粘连、肠扭转或疝造成的**机械性肠梗阻**；**粪便嵌塞伴溢液性腹泻**（表现与便秘相反，极易误判）；中毒性巨结肠；术后或药物引起的麻痹性肠梗阻；炎症性肠病或缺血造成的严重肠腔狭窄。**往机械性梗阻上再加一味刺激性泻药是反向操作**，这也是本草文献里少数几个「古典适应症可以直接翻译成现代影像检查申请」的地方。
即便确实是普通便秘，今天的顺序也不同。**五十岁前后新发的便秘是结直肠癌筛查指征**；其余一长串是：甲状腺功能减退、高钙血症、糖尿病、帕金森病、抑郁、长期卧床、饮水与膳食纤维不足、肠易激综合征，以及药物（阿片类、抗胆碱药、钙通道阻滞剂、铁剂与部分抗抑郁药都在其中）。这一串里有一项不是鉴别而是急症：**便秘伴背痛、鞍区麻木、或新出现的大小便失禁**，可能是脊髓或马尾受压，属于当天就要做影像的情况。
后加的两味各自都有分量。**大黄**是蒽醌类刺激性泻药：这一类已不是普通便秘的一线选择，长期使用与**结肠黑变病**及**失钾**相关，欧洲监管机构据此把蒽醌类泻药限制为短期使用；大黄根同时含**鞣质**，这也是用它可以先泻后秘的原因。**芒硝**是**含水硫酸钠**，即一次真实的**钠负荷**，在心衰、高血压、肾病中都不是中性事件；渗透性泻药与肠道准备制剂曾引起**急性肾损伤**与严重电解质紊乱 —— 要认真对待的是这个机制，而不是「泻得干净」这件事。另：**芒硝不是硝石**（硝酸钾）。
还有一点分类值得保留：**去掉两味攻下药的三味方就是增液汤**，本库已另立条目。两方之差，正是使之成为「泻下剂」而非「润燥剂」的那两味。本条记录的是组成与其思路，它不是给「肠道不动了」的人的指引。