Da Huang Gan Cao Tang (Rhubarb and Liquorice Decoction) dà huáng gān cǎo tāng · 大黄甘草汤

Safety. Two ingredients: 大黄 (rhubarb root and rhizome) and 甘草 (liquorice root). Two. Quantities, preparation and method of taking are deliberately not listed here. The line: 食已即吐者，大黄甘草汤主之 — for one who vomits as soon as food has gone down, this formula governs. Set it beside 大半夏汤 in the same batch and the contrast is the clearest thing on the page. 大半夏汤 is for food that comes back hours later; this one is for food that comes back at once. One is a stomach that has not emptied. The other is a stomach that will not accept. The classical text put them in the same chapter and separated them by a single character of timing, and that separation is still the useful part. Vomiting immediately after eating has a modern differential that includes gastric outlet obstruction, achalasia and severe reflux, hyperemesis of pregnancy, and — in infants — hypertrophic pyloric stenosis, whose hallmark is projectile vomiting in a hungry infant in the first weeks of life. This library does not sort that list and does not tell anyone which one they have. It says that a symptom carrying a named differential belongs to a clinician, and it says so in the same breath as the classical record. Now the two ingredients, and this is the reason the entry exists. Both of them lead to the same place. 大黄 is an anthraquinone stimulant laxative: it acts by irritating the bowel, and chronic use is associated with dependence, with melanosis coli, and with potassium loss. 甘草 contains glycyrrhizin, which produces a pseudo-aldosterone state — sodium retention, potassium loss, rising blood pressure — and the potassium loss is the mechanism that turns dangerous when liquorice is combined with digoxin or with a diuretic. Put the two in the same pot and there are two independent routes to hypokalaemia arriving together. Low potassium is not a laboratory curiosity: the fatal mechanism is ventricular arrhythmia. A stimulant laxative is also the wrong direction in obstruction — a point this library made in the previous batch and repeats here because it repeats in life. Rhubarb leaf, incidentally, carries oxalate; this formula uses the root. There is Chinese-language clinical literature on 大黄甘草汤, in postoperative nausea and in reflux-like pictures; small, limited methods. Recorded as existing; not recorded as established. Two ingredients — and the shortest safety paragraph on the page is the one about the heart.