柴胡（半斤味甘平） 黄芩（三两味苦寒） 芍药（三两味酸微寒） 半夏（半升
洗味辛温） 生姜（五两切味辛温） 枳实（四枚炙味苦寒） 大枣（十二枚擘甘温）
大黄（二两味苦寒）
上七味。以水一斗二升。煮取六升。去滓。再煎。温服一升。日三服。一方用大黄
二两。若不加大黄。恐不为大柴胡汤也。
柴胡黄芩之苦。入心而折热。枳实芍药之酸苦。涌泄而扶阴。辛者、散也。半夏之
辛。以散逆气。辛甘、和也。姜枣之辛甘。以和荣卫。
成氏云。方有缓急轻重。医当临时斟酌。如大满大实。坚有燥屎者。非驶剂则不能
泄。是以有大小承气之峻也。如不至大坚满。惟邪热甚而攻下者。又非承气汤之可投。
必也轻缓之剂。乃大柴胡汤。用以逐邪热也。是知大柴胡为下剂之缓者。
伤寒十三日不解。胸胁满而呕。日晡所发潮热。已而微利。此本柴胡证。下之而不
得利。今反利者。知医以丸药下之。非其治也。潮热者。实也。先宜小柴胡汤以解外。
后以柴胡加芒硝汤主之。
伤寒十三日再传经尽。当解之时也。若不解。胸胁满而呕者。邪气犹在表里之间。
此为柴胡汤证。若以柴胡汤下之。则更无潮热自利。医反以丸药下之。虚其肠胃。
邪气乘虚入腑。日晡所发潮热。热已而利也。潮热虽为热实。然胸胁之邪未已。故先与
小柴胡汤以解外。后以柴胡加芒硝。以下胃热。
Chai Hu (Bupleuri Radix, Ban Zhi) (half jin, sweet flavor, neutral nature), Huang Qin (Scutellariae Radix, San Liang) (three liang, bitter flavor, cold nature), Shao Yao (Paeoniae Radix, San Liang) (three liang, sour flavor, slightly cold nature), Ban Xia (Pinelliae Rhizoma, Ban Sheng, washed) (half sheng, pungent flavor, warm nature), Sheng Jiang (Zingiberis Rhizoma Recens, Wu Liang, sliced) (five liang, pungent flavor, warm nature), Zhi Shi (Aurantii Fructus Immaturus, Si Mei, roasted) (four pieces, bitter flavor, cold nature), Da Zao (Jujubae Fructus, Shi Er Mei, split) (twelve pieces, sweet flavor, warm nature), Da Huang (Rhei Radix et Rhizoma, Liang Er) (two liang, bitter flavor, cold nature).
The above seven herbs. Boil with one dou and two sheng of water. Decoct to obtain six sheng. Remove the dregs. Re-decoct. Take one sheng warm each time. Administer three times daily. In another version, Da Huang is used in an amount of two liang. If Da Huang is not added, it arguably cannot be called Da Chai Hu Tang.
The bitter properties of Chai Hu and Huang Qin enter the Heart channel to reduce heat. The sour and bitter properties of Zhi Shi and Shao Yao induce vomiting and purgation to support Yin. Pungent substances disperse. The pungency of Ban Xia disperses rebellious Qi. Pungent and sweet flavors harmonize. The pungent and sweet properties of Sheng Jiang and Da Zao harmonize Ying Wei (Nutritive and Defensive Qi).
Cheng Wuji stated: Formulas vary in their mildness, urgency, weight, and lightness; physicians should exercise discretion according to circumstances. If there is severe fullness and solidity with dry feces, only a potent agent can purge them; hence the existence of the harsh formulas Da Cheng Qi Tang and Xiao Cheng Qi Tang. If there is no severe hardness or fullness, but only excessive pathogenic heat requiring purgation, Cheng Qi Tangs are not suitable. One must use a mild and gentle formula, which is Da Chai Hu Tang, used to drive out pathogenic heat. Thus, it is known that Da Chai Hu Tang is a mild purgative among purgative formulas.
In Tai Yang disease lasting thirteen days without resolution, if there is chest and hypochondriac fullness with vomiting, tidal fever occurring at dusk, followed by slight diarrhea, this was originally a Xiao Chai Hu Tang syndrome. After incorrect purgation, diarrhea did not cease. Now, since there is diarrhea, it is known that the physician used pill-based purgatives, which was not the correct treatment. Tidal fever indicates excess heat. First, administer Xiao Chai Hu Tang to resolve the exterior. Subsequently, treat with Chai Hu Jia Mang Xiao Tang as the primary formula.
After thirteen days of Tai Yang disease, when the pathogen has completed its transmission through the meridians, it should resolve. If it does not resolve, and there is chest and hypochondriac fullness with vomiting, the pathogen remains between the exterior and interior. This is a Xiao Chai Hu Tang syndrome. If treated with Xiao Chai Hu Tang via purgation, there would be no tidal fever or spontaneous diarrhea. However, the physician incorrectly used pill-based purgatives, weakening the stomach and intestines. Pathogenic factors entered the fu organs taking advantage of the deficiency. Tidal fever occurs at dusk, and diarrhea follows the subsidence of heat. Although tidal fever indicates heat excess, the pathogen in the chest and hypochondrium has not yet resolved. Therefore, first administer Xiao Chai Hu Tang to resolve the exterior, then use Chai Hu Jia Mang Xiao Tang to purge gastric heat.