Leg Swelling

Leg swelling (leg edema) is when fluid builds up in the tissue under the skin of the lower legs, ankles, or tops of the feet. This swelling is not a disease in itself but a sign of another condition. The legs look bigger, shoes or socks feel tight and leave marks, and skin that is pressed for a few seconds may leave a dent. This page helps you recognize swelling patterns and know when to get checked, but it does not replace an examination by a doctor.

One Leg or Both Legs

The pattern of swelling helps the doctor look for the cause. Swelling in one leg, especially if it appears quickly and comes with pain, warmth, or redness, needs to be checked right away because it can be caused by a blood clot in a leg vein, which is covered on the Deep Vein Thrombosis page. Other causes of swelling in one leg are skin infection, injury, or a problem with the lymphatic vessels. Swelling in both legs more often comes from long-term vein problems, medicine side effects, or diseases that affect the whole body, such as heart failure, kidney disease, and liver disease.

The Link to the Heart

When the heart's pumping weakens or the right side of the heart is under strain, blood backs up in the veins and the pressure in them rises, so fluid seeps into the tissues. In heart failure, swelling in both legs usually comes with shortness of breath during activity or when lying down, tiring easily, and rapid weight gain. This condition is covered on the Heart Failure page. High pressure in the lung blood vessels and diseases of the sac around the heart can also cause leg swelling.

Causes Outside the Heart

A common cause is leg vein valves that do not close properly, so blood pools in the legs, which is covered on the Chronic Venous Insufficiency page. Medicines can also cause swelling, for example calcium channel blockers for blood pressure, nonsteroidal anti-inflammatory drugs, and corticosteroids. Do not stop your medicines on your own; talk to your doctor. Other causes include a low blood albumin level, an underactive thyroid gland, pregnancy, standing or sitting for a long time, and lymphedema. Swelling in other parts of the body, such as the hands, arms, or face, is covered on the Peripheral Edema page.

The doctor asks how long the swelling has been there, whether it is in one or both legs, whether it improves after sleep, and about other symptoms such as shortness of breath, pain, or changes in urination. A list of the medicines you take is also important. The physical examination checks whether the skin leaves a dent when pressed, the color and temperature of the skin, the leg pulses, the heart and lung sounds, and signs of fluid in the abdomen. If the swelling is in one leg, a vascular ultrasound is done to look for a clot in the deep veins, sometimes preceded by a D-dimer test. If the swelling is in both legs, blood tests assess kidney function, liver function, albumin, and thyroid, while a urine test looks for leaking protein. If a heart cause is suspected, an NT-proBNP test, an ECG, and echocardiography assess the heart's pumping, the valves, and the pressure in the lung blood vessels. A duplex ultrasound also assesses leaking vein valves in long-term vein problems.

Mild swelling in both legs after standing for a long time that goes away after rest is usually not dangerous. See a doctor if the swelling persists, increases, or comes with other symptoms. Go to the emergency room right away if a swollen leg comes with sudden shortness of breath or chest pain.

• Swelling in one leg, especially if it is painful, warm, or red
• Swelling in both legs with shortness of breath, tiring easily, or rapid weight gain
• Swelling that does not go down after a night's sleep
• Swelling with foamy urine, puffy eyes, or a swollen abdomen
• Swelling after starting a new medicine
• Sudden swelling during pregnancy, especially with a headache or blurred vision