Signs of edema include:

• Swelling or puffiness of the tissue directly under your skin, especially in your legs or arms
• Stretched or shiny skin
• Skin that retains a dimple (pits), after being pressed for several seconds
• Increased abdominal size

Edema occurs when tiny blood vessels in your body (capillaries) leak fluid. The fluid builds up in surrounding tissues, leading to swelling.

Mild cases of edema may result from:

• Sitting or staying in one position for too long
• Eating too much salty food
• Having premenstrual signs and symptoms
• Being pregnant

Edema can also be a side effect of some medications, including:

• High blood pressure medications
• Nonsteroidal anti-inflammatory drugs
• Steroid drugs
• Estrogens
• Certain diabetes medications called thiazolidinediones

In some cases, however, edema may be a sign of a more serious underlying medical condition. Several diseases and conditions may cause edema, including:

• Congestive heart failure. If you have congestive heart failure, one or both of your heart's lower chambers lose their ability to pump blood effectively. As a result, blood can back up in your legs, ankles and feet, causing edema. Congestive heart failure can also cause swelling in your abdomen. Sometimes, this condition can cause fluid to accumulate in your lungs (pulmonary edema), which can lead to shortness of breath.
• Cirrhosis. Fluid may accumulate in your abdominal cavity (ascites) and in your legs as a result of liver damage (cirrhosis).
• Kidney disease. When you have kidney disease, extra fluid and sodium in your circulation may cause edema. The edema associated with kidney disease usually occurs in your legs and around your eyes.
• Kidney damage. Damage to the tiny, filtering blood vessels in your kidneys can result in nephrotic syndrome. In nephrotic syndrome, declining levels of protein (albumin) in your blood can lead to fluid accumulation and edema.
• Weakness or damage to veins in your legs. If you have chronic venous insufficiency, the one-way valves in your leg veins are weakened or damaged, which allows blood to pool in your leg veins and causes swelling. Sudden onset of swelling in one leg accompanied by pain in your calf muscle can be due to a blood clot (deep vein thrombosis, or DVT) in one of your leg veins. If this occurs, seek medical help immediately.
• Inadequate lymphatic system. Your body's lymphatic system helps clear excess fluid from tissues. If this system is damaged — for example, by cancer surgery — the lymph nodes and lymph vessels draining an area may not work correctly, and edema can occur.
• Severe, long-term protein deficiency. An extreme lack (deficiency), of protein in your diet over a long period of time can lead to fluid accumulation and edema.

If you are pregnant, your body retains more sodium and water than usual due to the fluid needed by the fetus and placenta. This can increase your risk of developing edema.

Your risk of edema may be increased if you take certain medications, including:

• High blood pressure medications
• Nonsteroidal anti-inflammatory drugs
• Steroid drugs
• Estrogens
• Certain diabetes medications called thiazolidinediones

A chronic illness — such as congestive heart failure or liver or kidney disease — can increase your risk of edema. Also, surgery can sometimes obstruct a lymph node, leading to swelling in an arm or leg, usually on just one side.

If left untreated, edema can cause:

• Increasingly painful swelling
• Difficulty walking
• Stiffness
• Stretched skin, which can become itchy and uncomfortable
• Increased risk of infection in the swollen area
• Scarring between layers of tissue
• Decreased blood circulation
• Decreased elasticity of arteries, veins, joints and muscles
• Increased risk of skin ulcers