What Is Edema?

"Edema" is the medical term for swelling. Body parts swell from injury or inflammation. It can affect a small area or the entire body. Medications, pregnancy, infections, and many other medical problems can cause edema.

Edema happens when your small blood vessels leak fluid into nearby tissues. That extra fluid builds up, which makes the tissue swell. It can happen almost anywhere in the body.

Types of Edema

Peripheral edema. This usually affects the legs, feet, and ankles, but it can also happen in the arms. It could be a sign of problems with your circulatory system, lymph nodes, or kidneys.

Pedal edema. This happens when fluid gathers in your feet and lower legs. It’s more common if you’re older or pregnant. It can make it harder to move around in part because you may not have as much feeling in your feet.

Lymphedema. This swelling in the arms and legs is most often caused by damage to your lymph nodes, tissues that help filter germs and waste from your body. The damage may be the result of cancer treatments like surgery and radiation. The cancer itself can also block lymph nodes and lead to fluid buildup.

Pulmonary edema. When fluid collects in the air sacs in your lungs, you have pulmonary edema. That makes it hard for you to breathe, and it’s worse when you lie down. You may have a fast heartbeat, feel suffocated, and cough up a foamy spittle, sometimes with blood. If it happens suddenly, call 911.

Cerebral edema. This is a very serious condition in which fluid builds up in the brain. It can happen if you hit your head hard, if a blood vessel gets blocked or bursts, or you have a tumor or allergic reaction.

Macular edema. This happens when fluid builds up in a part of your eye called the macula, which is in the center of the retina, the light-sensitive tissue at the back of the eye. It happens when damaged blood vessels in the retina leak fluid into the area.

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Causes of Edema

Things like a twisted ankle, a bee sting, or a skin infection will cause edema. In some cases, like an infection, this may be helpful. More fluid from your blood vessels puts more infection-fighting white blood cells in the swollen area.

Edema can also come from other conditions or from when the balance of substances in your blood is off. For example:

Low albumin. Your doctor may call this hypoalbuminemia. Albumin and other proteins in the blood act like sponges to keep fluid in your blood vessels. Low albumin may contribute to edema, but it’s not usually the only cause.

Allergic reactions. Edema is a part of most allergic reactions. In response to the allergen, nearby blood vessels leak fluid into the affected area.

Obstruction of flow. If drainage of fluid from a part of your body is blocked, fluid can back up. A blood clot in the deep veins of your leg can cause leg edema. A tumor blocking the flow of blood or another fluid called lymph can cause edema.

Critical illness. Burns, life-threatening infections, or other critical illnesses can cause a reaction that allows fluid to leak into tissues almost everywhere. This can cause edema all over your body.

Congestive heart failure . When the heart weakens and pumps blood less effectively, fluid can slowly build up, creating leg edema. If fluid builds up quickly, you can get fluid in the lungs. If your heart failure is on the right side of your heart, edema can develop in the abdomen.

Liver disease. Severe liver disease, such as cirrhosis, causes you to retain fluid. Cirrhosis also leads to low levels of albumin and other proteins in your blood. Fluid leaks into the abdomen and can also cause leg edema.

Kidney disease. A kidney condition called nephrotic syndrome can cause severe leg edema and sometimes whole-body edema.

Pregnancy. Mild leg edema is common during pregnancy. But serious complications of pregnancy like deep vein thrombosis and preeclampsia can also cause edema.

Head trauma , low blood sodium (called hyponatremia), high altitudes, brain tumors, and a block in fluid drainage in the brain (known as hydrocephalus) can cause cerebral edema. So can headaches, confusion, unconsciousness, and coma.

Medications. Many medicines can cause edema, including:

When they cause swelling, usually it's mild leg edema.

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Symptoms of Edema

Your symptoms will depend on the amount of swelling you have and where you have it.

Edema in a small area from an infection or inflammation (like a mosquito bite) may cause no symptoms. On the other hand, a large allergic reaction (such as from a bee sting) may cause edema on your entire arm that can bring pain and limit your arm's movement.

Food allergies and allergic reactions to medicine may cause tongue or throat edema. This can be life-threatening if it interferes with your breathing.

Leg edema can make the legs feel heavy. This can affect walking. In edema and heart disease, for example, the legs may easily weigh an extra 5 or 10 pounds each. Severe leg edema can interfere with blood flow, leading to ulcers on the skin.

Pulmonary edema causes shortness of breath and sometimes low oxygen levels in the blood. Some people with pulmonary edema may have a cough.

There may be an indent or a “pit” that remains for a while after you push on the skin in some types of edema. This is called pitting edema. If the tissue springs back to its normal shape, it’s called non-pitting edema. It’s a symptom that may help your doctor figure out the cause of your edema.

Treatment of Edema

To treat edema, you often must treat its underlying cause. For example, you might take allergy medications to treat swelling from allergies.

Edema from a block in fluid drainage can sometimes be treated by getting the drainage flowing again. A blood clot in the leg is treated with blood thinners. They break down the clot and get drainage back to normal. A tumor that blocks blood or lymph can sometimes be shrunk or removed with surgery, chemotherapy, or radiation.

Leg edema related to congestive heart failure or liver disease can be treated with a diuretic (sometimes called a ''water pill'') like furosemide (Lasix). When you can pee more, fluid from the legs can flow back into the blood. Limiting how much sodium you eat can also help.

WebMD Medical Reference Reviewed by James Beckerman, MD, FACC on November 11, 2017

Sources

SOURCES:

American Family Physician: “Edema: Diagnosis and Management.”

Guyton, A.C. Textbook of Medical Physiology, 8th ed, Saunders, 1991.

Taylor, A.E. Circulation Research, 1981.

Mayo Clinic: “Pulmonary Edema,” “Lymphedema,” “Leg Swelling,” “Edema.”

Medicina: “Cerebral edema and its treatment."

MedlinePlus: "Edema."

Merck Manual: “Swelling During Late Pregnancy.”

National Eye Institute: “Facts About Macular Edema.”

University of Arizona Center on Aging: “Pedal Edema in Older Adults.”

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