Peripheral Edema

Peripheral swelling, or peripheral edema, happens when fluid leaks out of small blood vessels and builds up in the tissue under the skin. Because of gravity, the swelling is more often seen in the ankles and lower legs, especially later in the day, and it can also appear in the hands, arms, or lower back in people who lie down for long periods. If pressing the skin for a few seconds leaves a dent, the swelling is called pitting edema. This page helps you recognize possible causes and warning signs; it is not meant for working out the cause on your own. Swelling that is limited to the legs is also covered on the Leg Swelling page.

One Side or Both Sides

The pattern of swelling gives an early clue. Swelling in one leg or one arm, especially if it appears suddenly, is painful, or feels warm, needs to be checked for a blood clot in a deep vein, a skin infection, or an injury. Clots in the deep veins are covered on the Deep Vein Thrombosis page. Swelling on both sides is more often linked to causes that affect the whole body or both legs at once.

Possible Causes

A common cause is leg vein valves that do not close tightly, so blood pools in the legs, covered on the Chronic Venous Insufficiency page. Medicines can also cause swelling, especially blood pressure medicines in the calcium channel blocker class, anti-inflammatory drugs, hormone medicines, and some diabetes medicines. Causes from other organs include heart failure, kidney disease, liver disease, a low level of the protein albumin, an underactive thyroid gland, and high pressure in the blood vessels of the lungs. Problems with lymph flow cause lymphedema, a firm swelling that does not improve easily when the legs are raised. Mild swelling can also appear during pregnancy, before a menstrual period, in hot weather, or after sitting for a long time while traveling.

The Connection to the Heart

In heart failure, the heart cannot pump blood smoothly, so the body holds on to salt and water. The swelling is usually in both legs and comes with shortness of breath during activity or when lying down, tiring easily, and rapid weight gain over a few days. Heart failure is covered on the Heart Failure page. Because swelling has many causes, diuretic medicines should not be used without a diagnosis: they do not fix causes in the veins, the lymphatic system, or other medicines, and they can affect the kidneys and electrolyte levels.

Your doctor will ask when the swelling started, whether it affects one or both sides, whether it hurts, and whether it improves when you raise your legs. Other symptoms such as shortness of breath, changes in how much you urinate, an enlarging abdomen, or yellowing skin help point toward the heart, kidneys, or liver. A list of all your medicines and supplements is also reviewed, because medicines are often the cause. During the physical exam, the doctor presses on the skin to look for a dent, checks the skin and leg veins, listens to the heart and lungs, and looks at the veins in the neck.

If one leg swells suddenly, the doctor may order a D-dimer test and a vein ultrasound to look for a blood clot. If the swelling is on both sides, blood and urine tests assess kidney function, liver function, albumin, protein in the urine, and thyroid function. If heart failure is suspected, the doctor checks NT-proBNP or BNP and orders an ECG and an echocardiogram. Duplex ultrasound also assesses leaky vein valves, while lymphoscintigraphy is used if a lymph flow problem is suspected.

Mild swelling in both feet after sitting or standing for a long time that goes away after sleep is usually not dangerous. If swelling comes with sudden shortness of breath, chest pain, or coughing up blood, go to the emergency room right away. Make an appointment with a doctor if you have any of the following.

• Swelling that lasts more than a few days or keeps getting worse
• Swelling in one leg or one arm, especially if it is painful or warm
• Swelling with shortness of breath during activity or when lying down, or rapid weight gain
• Swelling that appears after starting a new medicine
• Swelling with less urine, foamy urine, or an enlarging abdomen
• Skin on the legs that changes color, thickens, or develops sores