Zhu Ya Zao

Gleditsia sinensis Lam. (Fabaceae) is a deciduous tree native to China, reaching 15-30 m, with stout branched thorns on the trunk and pinnately compound leaves. It produces large, dark brown leguminous pods, but the medicinal Zhu Ya Zao (literally 'pig-tooth pod') consists of the small, abortive, sickle-shaped underdeveloped pods, only 5-10 cm long, used in traditional Chinese medicine. The pods are rich in triterpenoid saponins (gleditsia saponins), which are strongly irritant and surface-active. In TCM, Zhu Ya Zao is acrid, warm, and slightly toxic; it enters the lung and large intestine channels to forcefully dispel phlegm, open the orifices, and induce sneezing or vomiting in patients with phlegm obstruction, sudden loss of consciousness, or wind-stroke. It is used cautiously and rarely in modern practice due to its strong action.