Edema is swelling caused by too much fluid trapped in the body's tissues. Edema can affect any part of the body. But it's more likely to show up in the legs and feet.
Medicines and pregnancy can cause edema. It also can be the result of a disease, such as congestive heart failure, kidney disease, venous insufficiency or cirrhosis of the liver.
Wearing compression garments and reducing salt in the diet often relieves edema. When a disease causes edema, the disease needs treatment, as well.
Symptoms of edema include:

Swelling of the foot, ankle and leg can be bad enough to leave a dimple, also known as a pit, in the skin after pressing on the area. This swelling, called edema, is the result of too much fluid in the tissues. Congestive heart failure or the vein not working well, also known as venous insufficiency, is often the cause.
Make an appointment to see a healthcare professional for swelling, stretched or shiny skin, or skin that holds a dimple after being pressed. See a healthcare professional right away for:
These can be signs of fluid buildup in the lungs, also known as pulmonary edema. It can be life-threatening and needs quick treatment.
After sitting for a long time, such as on a long flight, call your healthcare professional if you get leg pain and swelling that won't go away. Especially if the pain and swelling is on one side, these can be symptoms of a blood clot deep in the vein, also known as deep vein thrombosis, or DVT.
Edema occurs when tiny blood vessels in the body, also known as capillaries, leak fluid. The fluid builds up in nearby tissues. The leak leads to swelling.
Causes of mild edema include:
Edema also can be a side effect of some medicines. These include:
Sometimes edema can be a sign of a more serious condition. Illnesses that can cause edema include:
Congestive heart failure. Congestive heart failure causes one or both of the heart's lower chambers stop pumping blood well. As a result, blood can back up in the legs, ankles and feet, causing edema. It also can cause swelling in the stomach area. Congestive heart failure may cause fluid to build up in the lungs too. Known as pulmonary edema, this can lead to shortness of breath.
The following increases the risk of edema:
If left untreated, edema can cause: