Indications for Da Chaihu Tang (Major Bupleurum Decoction)

Da Chaihu Tang is a classic renowned formula from Zhang Zhongjing's Shanghan Lun (Treatise on Cold Damage). It is composed of "Chaihu (Bupleuri Radix) half a jin, Huangqin (Scutellariae Radix) three liang, Shaoyao (Paeoniae Radix) three liang, Banxia (Pinelliae Rhizoma) half a sheng (washed), Shengjiang (Zingiberis Rhizoma recens) five liang (sliced), Zhishi (Aurantii Fructus immaturus) four pieces, Dazao (Jujubae Fructus) twelve pieces, Dahuang (Rhei Radix et Rhizoma) two liang." Here the jin and liang are Han-dynasty units of measure. A Han-dynasty jin is roughly equivalent to about 250 grams today; a Han jin weighed sixteen liang, so one liang is about 15 modern grams.

However, today we generally do not use Zhang Zhongjing's dosages. The commonly recommended safe modern dosage is: Chaihu 12 g, Huangqin 6 g, Baishao (Paeoniae Alba Radix) 6 g, Fabanxia (prepared Pinellia) 6 g, Shengjiang 10 g, Zhishi 6 g, Dazao 4 pieces, Dahuang 6 g. Although Zhang Zhongjing's amounts look large, the patient took only one-sixth of the decoction each time. In practice this is similar to our modern dose, because when we prescribe this formula today, one package is drunk only once — just the first decoction, without a second boiling.

The Dahuang here should be raw Dahuang and added late (houxia). Dahuang does not tolerate prolonged boiling; if cooked too long its active constituents are destroyed. After the other herbs are done, add the Dahuang and boil for another five minutes. Da Chaihu Tang belongs to the harmonizing (he-fa) category of TCM formulas. Generally, for this type of formula, after straining out the herb residue, the remaining decoction should be brought to a boil again before drinking.

In Zhang Zhongjing's Shanghan Lun there are three passages concerning Da Chaihu Tang: 1. "In a Taiyang disease that has passed the channel stage for over ten days, purgation has been used two or three times inappropriately; four to five days later, if the Chaihu pattern is still present, first give Xiao Chaihu Tang. If vomiting does not stop, there is epigastric tension and depressed irritability, the condition has not resolved; giving Da Chaihu Tang and purging will cure it." 2. "In cold damage of over ten days, with heat bind in the interior and alternating chills and fever, give Da Chaihu Tang." 3. "In cold damage with fever, sweating that does not resolve the condition, a hard fullness in the chest, vomiting and diarrhea, Da Chaihu Tang governs."

From these three passages we can see that Da Chaihu Tang treats both constipation in Shaoyang disease and vomiting with diarrhea in Shaoyang disease. The first passage: after a Taiyang disease was wrongly treated with purgation, the patient developed the Xiao Chaihu Tang pattern of Shaoyang disease (alternating chills and fever, fullness and discomfort in the chest and hypochondrium, subdued mood and no desire to eat). After treatment with Xiao Chaihu Tang, vomiting continued, there was epigastric cramping discomfort and emotional irritability — this is the situation for Da Chaihu Tang. The second passage: a patient with cold damage (fever and aversion to cold) for over ten days develops heat bind in the interior with constipation, along with alternating chills and fever (the common saying of feeling now cold, now hot); this also calls for Da Chaihu Tang. The third passage: the patient first has chills and fever; after sweating (whether spontaneous or induced by the doctor with diaphoretics), the symptoms do not ease or disappear (sweating without resolution), there is epigastric fullness and discomfort, with both vomiting and diarrhea — again, Da Chaihu Tang is indicated.

Da Chaihu Tang is made by taking Xiao Chaihu Tang, removing Renshen (Ginseng Radix) and Gancao (Glycyrrhizae Radix), and adding Zhishi, Dahuang, and Shaoyao. Da and Xiao Chaihu Tangs, as well as Chaihu plus Mangxiao Tang (Xiao Chaihu Tang plus Mirabilitum), are the classic TCM formulas for treating Shaoyang disease. Among them, Da Chaihu Tang has traditionally been considered the treatment for the combined Shaoyang-Yangming pattern — that is, when the patient simultaneously has the Shaoyang pattern of "alternating chills and fever, fullness and discomfort in the chest, epigastrium and hypochondrium, subdued mood with poor appetite (most patients also have a bitter taste in the mouth)," and the Yangfu bowel-real pattern.

In the ancient edition of Shanghan Lun this formula did not contain Dahuang, but there is a note after the formula: "One version adds Dahuang two liang; if Dahuang is not added, I fear it is not really Da Chaihu Tang." Dahuang has a purgative action. It can treat the Yangming bowel-real pattern of "heat bind in the interior" — constipation — and, following the TCM principle of "treating obstruction by obstruction" (tongyin tongyong), can also use purgation to stop diarrhea, treating digestive diseases such as diarrhea and vomiting.

In Zhang Zhongjing's Shanghan Lun, Da Chaihu Tang was taken three times a day. I personally do not use it this way. When I prescribe Da Chaihu Tang, I usually have the patient take it once (one package, just the first decoction) and observe for eight hours. For constipation, observe whether bowel movement occurs within those eight hours; for vomiting and diarrhea, observe whether they continue. If after eight hours the symptoms have not eased, give another package. If symptoms ease within the eight-hour observation period, Dahuang must be omitted in subsequent doses — otherwise diarrhea will result. This formula should not be used for long; once the patient's symptoms ease, it should be stopped.

Da Chaihu Tang is now used for hepatobiliary diseases. Patients with cholecystitis, gallstones, gallbladder polyps, or hepatitis who present with the above symptoms respond well to Da Chaihu Tang. In the formula, Zhishi moves qi and stops pain, and Baishao softens the liver and stops pain, so the formula also has good antispasmodic and analgesic effects; modern use for biliary colic caused by hepatobiliary disease is very effective.

It should be noted that TCM formulas are prescribed based on the patient's symptoms, not on Western disease names. If a patient has one of the above diseases but lacks the indications for Da Chaihu Tang, the formula is not appropriate. Conversely, even if the patient does not have the above diseases but has other conditions — such as gastric or duodenal ulcer, food poisoning, and so on — as long as the indications for Da Chaihu Tang are present, the formula may be used. Patients often come to me holding Western disease names and asking how to use Chinese medicine; this approach is a waste of time. The decision to use a particular formula should be based on detailed symptoms.