Source 出处 · Shanghan Lun · Doses are not given here: they are set by a licensed practitioner for the individual.
Safety. Gancao Xiexin Tang is Banxia Xiexin Tang with the liquorice increased. One ingredient, in a larger share, is the entire difference — and because that ingredient is liquorice, it is also the safety headline of the formula.
The classical line describes focal distension that is full and hard, dry retching, restlessness and an inability to settle, and diarrhoea so frequent that the text counts it, with food passing undigested and audible rumbling in the abdomen. The Jingui Yaolüe uses the same formula name for 狐惑, a condition described as ulceration of the throat, the eyes and the genitals. Modern readers habitually map that description onto Behçet's disease; the mapping is suggestive and is repeated in the Chinese literature, but it is an interpretation of a symptom description, not a demonstrated equivalence, and this library does not settle the question.
Take the bowel picture first. Diarrhoea that runs for weeks and passes undigested food is, in any contemporary guidance, an indication for investigation rather than for tonic support. The standard workup for chronic diarrhoea (conventionally more than four weeks) covers bile acid diarrhoea, coeliac disease, inflammatory bowel disease, microscopic colitis, pancreatic exocrine insufficiency, hyperthyroidism, Clostridioides difficile, diabetic enteropathy, small intestinal bacterial overgrowth, and a long medication list that includes metformin, proton pump inhibitors, non-steroidal anti-inflammatory drugs, antibiotics, SGLT2 inhibitors, magnesium-containing preparations, and the GLP-1 receptor agonists now in wide use. The immediate danger in that state is not the diagnosis but the fluid and potassium loss — and that is exactly the danger liquorice amplifies. A person who is losing potassium from the bowel and taking a formula whose defining change is more liquorice is moving in the wrong direction on the single electrolyte that matters most.
Liquorice deserves the detail. Glycyrrhizin inhibits 11β-hydroxysteroid dehydrogenase type 2, so cortisol acts at the mineralocorticoid receptor and the body behaves as though it were receiving aldosterone: sodium and water retention, hypertension, and potassium wasting. Published case reports describe hypokalaemic hypertension, oedema, hypokalaemic myopathy, and rhabdomyolysis, and case series exist for people who were simply eating liquorice confectionery regularly. The risk is materially higher alongside thiazide or loop diuretics, digoxin, or any other potassium-lowering agent — hypokalaemia is the mechanism by which digoxin toxicity becomes dangerous. Because 甘草 is the one ingredient this formula deliberately raises, it is the formula in this family where that interaction deserves to be said plainly.
Take the ulcer picture second. Recurrent oral ulceration together with genital ulceration has its own differential: Behçet's disease, herpes simplex, inflammatory bowel disease, reactive arthritis, systemic lupus erythematosus, nutritional deficiency (iron, folate, vitamin B12), and drug-induced ulceration — nicorandil and non-steroidal anti-inflammatory drugs are the classic examples. One presentation must not be handled by correspondence or by self-treatment: acute, widespread painful oral erosions with skin lesions, blistering, mucosal involvement elsewhere, or fever could be erythema multiforme or Stevens-Johnson syndrome, and that is an emergency. Recurrent oral ulceration that does not heal within a few weeks also needs to be looked at directly, because oral squamous carcinoma can present that way.
The remaining identities repeat across this family: 半夏 is used only in processed form because the unprepared tuber irritates mucous membranes; 黄连 (Coptis) is not 胡黄连 (Picrorhiza) and carries berberine, a documented CYP and P-glycoprotein inhibitor that displaces bilirubin, which is why it is avoided in jaundiced newborns and in pregnancy and breastfeeding; 黄芩 (Scutellaria baicalensis) is not American skullcap, and skullcap-labelled supplements have been reported in liver-injury case series involving adulteration or misidentification; 人参 is Panax ginseng, distinct from 党参 and 西洋参; 干姜 is dried Zingiber officinale, not 高良姜; 大枣 is a dried fruit and a genuine sugar load. This entry records what a classical text did with a difficult convalescent picture. It is not a plan for chronic diarrhoea, and it is not a plan for ulceration.
甘草泻心汤就是半夏泻心汤加重了甘草。**一味药、加量使用，就是全部的差别** —— 而因为这一味是甘草，它也同时成了本方的安全头条。
条文描写的是**心下痞硬而满、干呕、心烦不得安**，以及腹泻频繁到条文要计数、**谷不化**（食物不化）、腹中雷鸣。《金匮要略》以同一个方名治**狐惑**，描述为咽喉、眼目与前阴的蚀烂。现代读者习惯把这段描述对应到白塞病；这个对应在中文文献里被反复提及、也有提示性，但它是**对一组症状描述的解释，不是已被证明的等同关系**，本库不裁决这个问题。
先看肠道那一半。**持续数周、完谷不化的腹泻**，在任何当代临床指引里都是**检查指征**而不是进补指征。慢性腹泻（通常指超过四周）的常规检查路径包括：胆汁酸性腹泻、乳糜泻、炎症性肠病、显微镜下结肠炎、胰腺外分泌功能不全、甲状腺功能亢进、艰难拟梭菌感染、糖尿病性肠病、小肠细菌过度生长，以及一长串药物 —— 二甲双胍、质子泵抑制剂、非甾体抗炎药、抗生素、SGLT2 抑制剂、含镁制剂，以及今天广泛使用的 GLP-1 受体激动剂。这种状态下最紧迫的危险**不是诊断，而是水与钾的丢失** —— 而这恰恰是甘草会放大的那个危险。一个正在从肠道丢钾的人，服一张把甘草特意加重的方子，是在最要紧的那一项电解质上往错的方向走。
甘草值得写细一点。**甘草酸抑制 11β-羟基类固醇脱氢酶 2 型**，于是皮质醇作用于盐皮质激素受体，身体表现得像是接到了醛固酮：钠水潴留、血压升高、排钾。公开的病例报告描述了低钾性高血压、水肿、低钾性肌病乃至横纹肌溶解，也有仅仅长期食用甘草糖果的病例系列。**与噻嗪类或袢利尿剂、地高辛或任何其它降钾因素并用时风险明显升高** —— 低钾正是使地高辛中毒变得致命的机制。因为甘草是本方**唯一特意加重**的一味，这是这一族里最该把这件事说清的一方。
再看蚀烂那一半。**复发性口腔溃疡合并外阴溃疡**有它自己的鉴别清单：白塞病、单纯疱疹、炎症性肠病、反应性关节炎、系统性红斑狼疮、营养缺乏（铁、叶酸、维生素 B12），以及药物性溃疡 —— 尼可地尔与非甾体抗炎药是最典型的两个例子。其中有一种表现**不能靠通信或自行处理**：急性、广泛、疼痛的口腔糜烂伴皮损、水疱、其它部位黏膜受累或发热，可能是多形性红斑或 Stevens-Johnson 综合征，**那是急症**。超过数周不愈的复发性口腔溃疡也需要当面看，因为口腔鳞癌可以这样起病。
其余辨物与本族各方相同：**半夏**只用炮制品，生品刺激黏膜；**黄连**（Coptis）不是**胡黄连**（Picrorhiza），含小檗碱 —— 已被证实的 CYP 与 P-糖蛋白抑制剂，且置换胆红素，故黄疸新生儿不宜、孕期与哺乳期回避；**黄芩**（Scutellaria baicalensis）不是美黄芩，标称黄芩属的补充剂有肝损伤病例报道且常牵涉掺伪与误判；**人参**是 Panax ginseng，与**党参**、**西洋参**不同物；**干姜**是姜的干燥根茎，不是**高良姜**；**大枣**是干果，是一次真实的糖负荷。
本条记录的是一部古典文献如何处理一个棘手的病后局面。它不是慢性腹泻的方案，也不是溃疡的方案。