Deficiency of fluid is caused by factors such as injury of fluid by heat, excessive depletion and insufficient production. 1. Heat injures the fluid: for example, the external infection of dry heat, burns the fluid and causes fluid deficiency. 2. Excessive depletion: for example, patients due to vomiting and diarrhea, sweating, excessive urination, or chronic illnesses that lead to excessive depletion of fluid, showing dryness and astringency and other signs of fluid deficiency. 3. Generation of insufficient: due to drinking too little water, or visceral gas deficiency, visceral tissue loss of moistening, functional impairment so that insufficient production of fluid, which leads to the performance of fluid deficiency. Fluid deficiency may also have other reasons, it is recommended that patients need to go to the hospital in a timely manner when discomfort occurs, by the Chinese medicine practitioner to identify the evidence to be treated, to avoid blind use of medication to produce adverse effects.