The exogenous pathogenic factors of the disease include wind, dampness or sore infection while the internal causes include the congenitally weak physique or acquired weak constitution. If the body resistance is weak, pathogenic factors will stay inside the body and impair viscera, causing the dysfunctions of the lung, spleen and kidney; if the lung qi is stagnated, the lung will fail to dredge water passage; if the spleen qi is stagnated, the spleen will fail to promote the transportation and distribution of water.

If the kidney qi is deficient, the kidney will fail to promote the transformation of qi and normal water metabolism; if the triple energizer fails to regulate water flow and the urinary bladder will fail to store and excrete urine, water and dampness will not circulate normally and accumulate in the skin and muscle, giving rise to edema. Therefore, the pathogenesis of edema can be summarized as "The primary cause lies in the kidney, the secondry cause in the lung and the treatment in the spleen."