Purgative method in Shang Han Lun

Purgative method (Xia Fa –下法) was one of eight methods （八法）in Shang Han Lun （伤寒论 Treatise on Cold Damage and Miscellaneous Disease）by Zhang Zhong-jing （张仲景） in the East Han Dynasty (3rd century AD).
This method functions in relieving constipation and eliminating indigested food-excessive heat from the gastrointestinal tract, and was mainly used for treatment of the yang ming fu zheng (the yang brightness fu-organ syndrome).
Under this method in Shang Han Lun, there are 5 main formulae for different indications in yang ming fu zheng (阳明腑证yang brightness fu-organ syndrome) – they are Tiaowei Chengqi Tang (调胃承气汤 Stomach-Regulating Purgative Decoction), Xiao Chengqi Tang （小承气汤 Minor Purgative Decoction）, Da Chengqi Tang （大承气汤 Major Purgative Decoction）, Maziren Wan （麻子仁丸 Hemp Seed Pill） and Guan Chang Fa（灌肠法Enema for Constipation）. There are also a number of formulae that combine purgative method with other methods. In this article, we will discuss the 5 formulae listed above, and then another 3 formulae that combine purgative with other methods.