Three Xiexin Decoctions from the Shanghan Lun for Epigastric Distension and Persistent Diarrhea
Banxia Xiexin Tang, Shengjiang Xiexin Tang, and Gancao Xiexin Tang in Zhang Zhongjing's Treatise on Cold Damage (Shanghan Lun) are three formulas for digestive tract diseases.
Original text from the Shanghan Lun:
"When cold damage has lasted five or six days and there is vomiting with fever, the Chaihu Tang pattern is present; if other drugs are used to precipitate and the Chaihu pattern remains, administer Chaihu Tang again. Although precipitation has been used, this is not a reversal; there will be steaming, shaking, and then resolution through sweating. If there is fullness below the heart with hard pain, this is chest bind, treated by Daxianxiong Tang. If there is only fullness without pain, this is pi (glomus); Chaihu is not appropriate—Banxia Xiexin Tang is suitable. Banxia Xiexin Tang: Banxia (Pinelliae Rhizoma) half sheng (washed), Huangqin (Scutellariae Radix), Ganjiang (Zingiberis Rhizoma), Renshen (Ginseng Radix) each 3 liang, Huanglian (Coptidis Rhizoma) 1 liang, Dazao (Jujubae Fructus) 12 pieces (broken), Gancao (Glycyrrhizae Radix) 3 liang (honey-fried). Boil these seven herbs in one dou of water to six sheng, strain, then decoct again to three sheng; take one sheng warm three times a day."
"After cold damage with sweating has resolved, if there is disharmony in the stomach, glomus and hardness below the heart, dry eructation with food odor, water qi beneath the hypochondria, rumbling in the abdomen, and diarrhea, Shengjiang Xiexin Tang governs. Shengjiang Xiexin Tang: Shengjiang (Zingiberis Rhizoma recens) 4 liang (sliced), Gancao 3 liang (honey-fried), Renshen 3 liang, Ganjiang 1 liang, Huangqin 3 liang, Banxia half sheng (washed), Huanglian 1 liang, Dazao 12 pieces (broken). Boil these eight herbs in one dou of water to six sheng, strain, then decoct to three sheng; take one sheng warm three times a day."
"When cold damage or wind-strike is mistakenly treated by precipitation, with the patient experiencing diarrhea dozens of times a day, undigested food, rumbling in the abdomen, glomus and hardness with fullness below the heart, dry retching, vexation and unease, the physician seeing the glomus below the heart thinks the disease is not resolved and precipitates again, making the glomus worse. This is not heat bind, but simply deficiency in the stomach with hostile qi rising upward, hence the hardness. Gancao Xiexin Tang governs. Gancao 4 liang (honey-fried), Huangqin 3 liang, Banxia half sheng (washed), Dazao 12 pieces (broken), Huanglian 1 liang, Ganjiang 3 liang. Boil these six herbs in one dou of water to six sheng, strain, then decoct to three sheng; take one sheng warm three times a day."
These three formulas are very similar. Later physicians held that Gancao Xiexin Tang also requires Renshen 3 liang, but the original text does not list it, and the passage explicitly says only six herbs; adding Renshen would make seven, contradicting the context. So this is not adopted for now.
The decocting method for all three differs from ordinary TCM decoctions: first boil with one dou (ten sheng) of water down to six sheng, strain out the dregs, then decoct the strained liquid alone down to three sheng. The sheng and dou here are Han-dynasty units, not modern ones. One Han dou can be converted to about 1000 ml today; one Han liang to about 3–5 g; Banxia is commonly used at 6–10 g. So when preparing these formulas, one may soak them in 1 liter of purified water for 10 minutes, then boil over strong then gentle heat to about 600 ml, strain, then decoct the liquid alone to 300 ml, taking about 100 ml three times a day. Both Chaihu Tang and the Xiexin Tangs belong to TCM "harmonizing" methods; by TCM decocting convention, harmonizing formulas are prepared this way—first boil and strain, then decoct the strained liquid.
From the original text of the Shanghan Lun, the symptoms of these three formulas resemble modern acute gastroenteritis. "Glomus and hardness below the heart" means epigastric and abdominal fullness and discomfort; "rumbling in the abdomen" is borborygmus; "undigested food" means the patient passes food unchanged, i.e., indigestion; "dry eructation with food odor" means dry retching with a foul, rotten breath; "water qi beneath the hypochondria" means fluid accumulation in the gastric or abdominal cavity producing a splashing sound; "vexation and unease" means vexation and insomnia. These symptoms are common in digestive tract diseases, especially acute gastroenteritis.
The Shanghan Lun is thus a book of great clinical value. Zhang Zhongjing described symptoms in meticulous detail. TCM formula selection emphasizes pattern differentiation, and the key to pattern differentiation lies in collecting the patient's various signs. Clinicians today are very familiar with these symptoms; reading such passages, one has great confidence in Zhang Zhongjing's clinical experience—he was not guessing, but summarizing from real practice.
Huanglian (Coptis), used in all three formulas, has had its antidiarrheal active ingredient berberine extracted by modern pharmaceutical companies and made into berberine tablets for diarrhea and vomiting from acute gastroenteritis; it works reasonably well, though it is now classified as a Western drug.
But in my experience, berberine alone sometimes fails to solve the patient's problem; one must choose one of these three Xiexin Tang formulas and decoct it for better effect, especially for patients with long-persisting diarrhea. Some patients never fully recover on berberine alone but improve much faster after taking a Xiexin Tang.
The Huangqin and Banxia used in Xiexin Tang are important herbs for fever and vomiting; Ganjiang warms the interior and dispels cold; Renshen fortifies the spleen and stomach; Dazao both strengthens the spleen and stomach and harmonizes the flavor of the formula; Shengjiang not only enhances Banxia's antiemetic effect but also has a strong diuretic action.
Gancao Xiexin Tang is the base formula; the other two are modifications built on it. If the patient feels nauseated and wants to vomit, Banxia Xiexin Tang is more suitable. If the patient is nauseated with obvious succussion sounds, Shengjiang Xiexin Tang should be chosen.
Gancao Xiexin Tang is also used to treat "huo-hu disease," now called Behcet's disease or Behcet syndrome, a chronic systemic vasculitic inflammatory disorder. It is persistent and recurrent and can affect multiple organs, including the mouth, skin, joints and muscles, eyes, blood vessels, heart, lungs, and nervous system. Clinical signs include recurrent oral and genital ulcers, skin rashes, erythema nodosum of the lower limbs, ocular iritis, esophageal ulcers, small or large intestinal ulcers, and joint swelling and pain. Cancer patients after radiotherapy and chemotherapy also show similar symptoms, and these three Xiexin Tang formulas are also effective.
In another of Zhang Zhongjing's works, Essential Prescriptions from the Golden Cabinet, there is this passage: "Huo-hu disease resembles cold damage; the person is taciturn and wants to sleep but cannot close the eyes, restless lying and rising; erosion of the throat is called huo, erosion of the privy parts is called hu. The patient does not want to eat or drink and hates the smell of food; the face now red, now black, now white; when erosion is in the upper part, the voice is hoarse—Gancao Xiexin Tang governs." These symptoms resemble Behcet's disease but also some mental disorders; the very name "huo-hu" is related to mental illness. The Japanese text Kanpo Igaku by Tsumura Shinjin records cases in which Japanese Kampo doctors used Gancao Xiexin Tang for various mental disorders; one female patient had a very strange symptom—sleepwalking every night, and dancing while sleepwalking—who recovered after taking Gancao Xiexin Tang.
Clearly, Gancao Xiexin Tang is not limited to gastroenteritis; as long as the patient's clinical symptoms match the formula pattern, it is very effective. We must inherit such ancient therapeutic experience and not deny its practicality merely because it is old.
According to Zhang Zhongjing, the patients suited to the three Xiexin Tangs developed epigastric distending pain and persistent diarrhea during the course of febrile "cold damage" or "wind-strike," either due to mistaken treatment or disease progression. But as Professor Hu Xishao noted, sometimes it is not mistaken treatment; more likely the patient already had a weak stomach, so digestive reactions appear after cold damage or wind-strike. We now know that after some viruses or bacteria infect the body, besides causing fever they also attack the digestive and nervous systems.
Some patients also have food allergies; ancient doctors did not understand this well and attributed diarrhea to mistaken treatment, but that is not really so.
For example, Europeans are descendants of nomadic peoples whose diet drove a genetic mutation: they still produce lactase to digest lactose as adults, so drinking milk causes no problem. Fewer than 30% of East Asians carry this mutation, so the remaining 70% may develop diarrhea and other adverse reactions after drinking milk.
Other people, also through genetic mutation, have especially high alcohol dehydrogenase levels and can drink enormous amounts. But not everyone is like this; some have low alcohol dehydrogenase levels and cannot touch even alcoholic drinks.
Such patients easily develop abdominal distension and diarrhea from drinking milk or alcohol, and they can be treated with Xiexin Tang.