It is a fluid swelling that accumulates beneath the skin, in the space where the Wei Qi circulates. You can identify it by the fovea sign: when pressing with the finger on the swollen area, the "impression" of the finger remains marked in the form of a hollow and it takes a little while to refill. Socks, for example, leave marks on the skin.

Edema mainly comes from Spleen-Yang deficiency, Lung or Kidney Yang deficiency. These three organs are involved in the transformation and transportation of the Body Fluids. Deficiency of any of them prevents proper transformation and causes the fluid to leave its normal pathways, invading the space between skin and muscles.

• If the deficiency is of Lung Yang, edema will mainly appear in the upper part like the face or hands.
• If it is due to Spleen-Yang deficiency, it is the middle part that will present edema, the abdomen.
• If the deficiency is in Kidney Yang, the lower part of the body is affected, like legs and ankles.