Edema is the abnormal accumulation of fluid in the extracellular spaces and tissues of the body. It can be caused by a variety of factors, including inflammation, allergies, high sodium levels, reduced excretion of fluids, decreased osmotic pressure, and reduced venous and lymphatic drainage. In Chinese medicine, edema is caused by disruptions to the body's fluid metabolism and can be classified as yin or yang edema. Yang edema is acute and affects the upper body, while yin edema is chronic and affects the lower body. Treatment for edema in Chinese medicine focuses on addressing the underlying causes and restoring the normal movement of fluids in the body.