Xiao Wuchen Tang: Treating Stomach Pain and Hematochezia

Xiao Wuchen Tang (“Minor Black and Chen Fragrance Decoction”) comes from the Shaoxing supplementary formulas of the Taiping Huimin Heji Jufang. It is composed of: Wuyao (Lindera root, pith removed) ten liang (300 g), Gancao (Licorice, stir-fried) one liang (30 g, skin and hairs removed, dried), and Xiangfu (Cyperus) twenty liang (600 g). Powder the three herbs together. Each dose: take one qian (3 g), add a little salt (or none), and infuse with boiling water (taken as a powder infusion), at any time, twice daily.

This formula harmonizes the middle and quickens qi. It treats stabbing epigastric and abdominal pain and hematochezia caused by unsmooth qi movement. Wuyao and Xiangfu in the formula both move qi and stop pain; they are pungent, bitter and warm, aromatic and drying, and act specifically in the qi portion, being able to diffuse and disperse. Used together, they excel at removing qi stagnation and stopping pain. But both Wuyao and Xiangfu are warm-drying substances, and must be assisted by a mild, harmonizing, moderate herb like sweet Gancao, so they do not become overly warm-drying and attack the body’s righteous qi. However, Gancao supplements the middle and boosts qi, and its cloying nature may obstruct the diaphragm; if used in too large a dose it will worsen qi stagnation. Hence in this formula Gancao is used at only one-twentieth the dose of Xiangfu and one-tenth that of Wuyao. Moreover, the Gancao is processed by stir-frying, not honey-frying; honey-fried Gancao is made with honey and is more cloying than raw Gancao, whereas stir-fried Gancao reduces the cloying side effect.

This Xiao Wuchen Tang in the Taiping Huimin Heji Jufang is actually a “decocted powder” taken as a soup, with each dose only 3 g — not a large actual dose. Xiao Wuchen Tang can be used for acute or chronic gastroenteritis presenting with qi-stagnation stomach pain and bloody stool, and to relieve pain in patients with cholecystitis, gallstones, chronic hepatitis, gastric cancer, liver cancer, gallbladder cancer or cholangiocarcinoma. Modern pharmacology shows that Wuyao, Xiangfu and Gancao each have some analgesic effect; used together the analgesic effect is better.

Xiao Wuchen Tang has a simple composition and is convenient to use; it is a relatively ideal formula for qi-stagnation stomach pain. It can speed intestinal peristalsis and promote gastric emptying. If a patient has long-standing gastric distension, stomach pain and bloody stool, Xiao Wuchen Tang may be processed into pills the size of a parasol-tree seed; take 10–15 pills with plain water, 2–3 times daily.