Edema is the result of tiny blood vessels in the body leaking fluid that eventually builds up in the surrounding tissues, explains Mayo Clinic. The blood vessels may begin to leak for a variety of reasons, including staying in one position for too long, premenstrual symptoms and pregnancy.
Certain medications, such as high blood pressure medications, nonsteroidal anti-inflammatory drugs, estrogens and thiazolidinediones, can also cause the blood vessels to leak fluid, according to Mayo Clinic. Edema can also result from congestive heart failure, cirrhosis, kidney disease, and weakness or damage to veins in the legs. Mild cases of edema typically go away naturally; however, medical treatment is sometimes necessary for more severe edema.