Chai hu, the chief herb, combined with the deputy herb, huang qin, vent the lesser yang, and also clear heat from the liver and gallbladder. Another deputy, zhi shi, which is a strong regulator of qi movement, breaks up qi stagnation and reduces focal distention and fullness in the chest and abdomen. Da huang, another deputy, drains heat excess and facilitates the flow of bile. When combined with the da huang, its ability to drain the clumping of heat in the interior is greatly strengthened. Shao yao and ban xia are the assistants in the formula. Shao yao nourishes the blood, softens the liver and treats abdominal pain and distention. Ban xia also can harmonize the stomach qi and direct rebellious stomach qi downward. Sheng jiang and da zao are chosen as the envoys in this formula. They regulate the nutritive and protective qi, and assist in the release of the pathogenic influence. So the main function of the formula is to drain heat excess in the gallbladder and stomach.