2. Changes in Drug Combinations

2. Changes in Drug Combinations

In formulas, adjusting the combination of herbs can alter the primary function of the formula. For example, Mahuang Tang is a specialized formula for treating wind-cold with exterior symptoms; the formula only achieves this effect when Gui Zhi is combined with Mahuang. If gypsum is combined with Mahuang, it treats exterior cold with internal heat; if Aconite is combined with Mahuang, it treats exterior cold with internal deficiency. Similarly, when a condition is characterized by internal heat and excess, we should employ a downward method—Rhubarb is the main herb. If internal heat is severe and the stomach feels full, with heart discomfort and abdominal distension, and constipation, then Rhabarbar is combined with Mang Xiao to use salty cold to release heat and attack excess, as in the Cheng Qi Tang; if the stomach is full and the heat is not severe, with a feeling of fullness in the lower abdomen and abdominal distension, then Rhabarbar is combined with Zhishi and Houpo to disperse the accumulation, as in the Xiao Cheng Qi Tang; if both heat and accumulation are present, and the patient experiences fullness, bloating, dryness, and excess, then a combination of Niu Xiao, Huang, Houpo, and Sheng is necessary, as in the Da Cheng Qi Tang. Furthermore, a single herb can exhibit completely different effects depending on how it is combined with other herbs—for example, when Mahuang is combined with Gui Zhi, it clears the exterior; when Mahuang is combined with Apricot Kernel, it stops coughing; when Mahuang is combined with Gypsum, it has a diuretic effect.