Simo Tang: The Representative TCM Formula for Qi Stagnation and Abdominal Distension

In Volume 2 of the Revised Yan’s Formulas to Aid the Living (Chongding Yan’s Jisheng Fang) there is a formula called “Simo Tang” (Four-Ground Decoction), the representative TCM formula for treating qi stagnation with abdominal distension. It is composed of equal parts of Renshen (Ginseng), Binglang (Areca nut), Chenxiang (Aquilaria wood) and Tiantai Wuyao (Lindera root). Because the herbs are ground by vigorous grinding in water and taken warm, it is named “Four-Ground Decoction.”

Simo Tang belongs to the qi-regulating formulas of TCM. Its functions are to break up stagnation and downbear counterflow, and to supplement qi and support the zheng (healthy qi). It Indicates impairment by the seven emotions, panting and shortness of breath, fullness and oppression in the chest and diaphragm, glomus and fullness below the heart, and inability to eat. The original text notes its preparation: “Take the above four herbs, grind each vigorously in water to obtain 300 ml, boil three to five times, and take warm; or it is even better to take with Yangzheng Dan.”

Yangzheng Dan is also an ancient formula, but because it uses highly toxic herbs of poor safety such as mercury, it has now been abandoned. For patients with deficiency and more severe panting, Yangzheng Dan may be replaced by other medicines, such as Jinkui Shenqi Wan or Guipi Wan.

The symptoms described for Simo Tang closely resemble the clinical pictures of what modern medicine calls bronchial asthma, pulmonary emphysema, chronic obstructive pulmonary disease, chronic gastritis, chronic cholecystitis, chronic hepatitis, and some psychiatric disorders. Hence today this formula is often used for the above diseases when they present with chest and diaphragmatic fullness, panting and shortness of breath. It may also be used as adjunctive therapy for respiratory or digestive tumors presenting with the above symptoms, or for such symptoms arising after radiotherapy or chemotherapy.

In Simo Tang, Binglang, Chenxiang and Tiantai Wuyao all treat qi stagnation, while Renshen supplements qi. This combined approach of supplementation and dissipation embodies the TCM spirit of eliminating pathogenic factors without forgetting to support healthy qi. Because of its remarkable efficacy, Simo Tang has always been valued. Today, pharmacies commonly stock the ready-made Chinese patent medicine Simo Tang Oral Liquid.

Simo Tang also has several common modifications. If the patient is robust with excess qi and severe qi binding, presenting with sudden syncope after great anger and abdominal fullness and distension, remove Renshen and add Muxiang (Aucklandia) and Zhishi (Immature bitter orange) to move qi and break binding; this is called Wumo Tang (Five-Ground Decoction). If qi stagnation causes constipation with abdominal fullness or distending pain, add Zhishi and Dahuang (Rhubarb) to loosen the bowels and guide stagnation; this is Liumo Tang (Six-Ground Decoction). If qi stagnation attacks the stomach with poor appetite, add on the basis of Simo Tang Jiao Shanzha (charred Hawthorn), Jiao Shenqu (charred Medicated leaven), Chao Jineijin (fried Chicken gizzard lining), Chao Guya (fried rice sprout) and Chao Maiya (fried barley sprout) to digest food and harmonize the stomach. If qi depression is severe with palpitations and insomnia, add Suanzaoren (Sour jujube seed), Baiziren (Biota seed), Longgu (Dragon bone), Muli (Oyster shell), Hehuanhua (Albizia flower), Yejiaoteng (Polygonum multiflorum vine), Lingzhi (Reishi) and Fushen (Poria with hostwood) to calm the spirit and aid sleep; Simo Tang may also be combined with Ganmai Dazao Tang. If panting is severe, combine Simo Tang with Sanzi Yangqin Tang to downbear qi and calm wheezing. If qi surges upward to strike the heart, add Guizhi (Cinnamon twig), Xuanfuhua (Inula) and Daizheshi (Hematite) to pacify surging qi and downbear counterflow. For patients with postoperative intestinal adhesions and incomplete intestinal obstruction, this formula may be modified with Yanhusuo (Corydalis), Chuanlianzi (Melia), Xiatianwu (Corydalis decumbens), Baishao (White peony) and Laifuzi (Radish seed) to smooth qi, open the abdomen and stop pain, or used together with Muxiang Shunqi Wan. For patients with severe qi stagnation and constipation, Simo Tang may be combined with Da Chengqi Tang, Xiao Chengqi Tang, Tiaowei Chengqi Tang or Zengye Chengqi Tang.

Simo Tang may also be decocted; for adults the usual decoction dose is 6–10 g of each herb. When the above accompanying symptoms are present, the dose of each herb may be adjusted according to the patient’s specific response.