What Is Edema?

“Edema” is the medical term for swelling. Parts of the body 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 occurs when your small blood vessels leak fluid into nearby tissues. This extra fluid builds up, causing the tissue to swell. It can happen almost anywhere in the body.

What Are the Types of Edema?

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

Pedal edema. This happens when fluid collects in your feet and lower legs. It is more common if you are older or pregnant. It can make it harder to move around, partly because you may not have much feeling in your feet.

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

Pulmonary edema. You have pulmonary edema when fluid collects in the air sacs in your lungs. This makes it hard to breathe and gets worse when you lie down. You may have a fast heartbeat, feel as if you are suffocating and sometimes cough up foamy, bloody sputum. If it comes on suddenly, you should go to the hospital as an emergency.

Cerebral edema. This is a very serious condition caused by fluid buildup in the brain. It can happen when you hit your head hard, when a blood vessel becomes blocked or bursts, or when you have a tumor or an allergic reaction.

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

What Causes Edema?

Things such as a sprained ankle, a bee sting or a skin infection cause edema. In some cases, such as infection, this can be helpful. More fluid from your blood vessels brings more infection-fighting white blood cells to the swollen area. Edema can also result from other conditions or when the balance of substances in your blood is disturbed.

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 can contribute to edema, but it is usually not the only cause.

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

Obstruction of flow. If the drainage of fluid from a part of your body is blocked, the 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 of 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 throughout your body.

This can cause edema throughout your body.

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

Liver disease. Serious liver diseases such as cirrhosis cause 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 disorder called nephrotic syndrome can cause severe leg edema and sometimes edema throughout the body.

Pregnancy. Mild leg edema is common in pregnancy. However, serious complications of pregnancy, such as deep vein thrombosis and preeclampsia, can also cause edema.

Head trauma, low blood sodium (called hyponatremia), high altitudes, brain tumors and a blockage of fluid drainage in the brain (known as hydrocephalus) can cause cerebral edema. It can also cause headaches, confusion, loss of consciousness and coma.

Medications. Many medications can cause edema, including:

• NSAIDs (such as ibuprofen and naproxen)
• Calcium channel blockers
• Corticosteroids (such as prednisone and methylprednisolone)
• Pioglitazone and rosiglitazone
• Pramipexole

When they cause swelling, it is usually mild leg edema.

What Are the Symptoms of Edema?

Your symptoms will depend on how much swelling you have and where it is. Edema in a small area caused by infection or inflammation (such as a mosquito bite) may cause no symptoms at all. On the other hand, a large allergic reaction (such as a bee sting) can cause edema in your entire arm, which can be painful and limit the movement of your arm.

Food allergies and allergic reactions to medication can cause swelling of the tongue or throat. 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 with heart disease, for example, the legs can easily become 2 to 5 kg heavier each. Severe leg edema can interfere with blood flow, leading to skin ulcers. Pulmonary edema causes shortness of breath and sometimes low oxygen levels in the blood. Some people with pulmonary edema may have a cough. In some types of edema, pressing on the skin leaves a dent, or “pit,” that remains for a while. This is called pitting edema. If the tissue springs back to its normal shape, it is called non-pitting edema. This is a sign that can help your doctor understand the cause of your edema.

How Is Edema Treated?

To treat edema, you usually need to treat the underlying cause. For example, you can take allergy medication to treat swelling caused by allergies. Edema caused by a blockage in fluid drainage can sometimes be treated by getting the drainage flowing again. A blood clot in the leg is treated with blood thinners (anticoagulants). These medicines do not dissolve the clot directly; they stop it from growing and prevent new clots from forming, while the body gradually breaks down the clot itself. A tumor blocking blood or lymph can sometimes be shrunk or removed with surgery, chemotherapy or radiation.

Leg edema due to congestive heart failure or liver disease can be treated with a diuretic (sometimes called a ”water pill”) such as furosemide (Lasix). When you urinate more, fluid in the legs can flow back into the blood. Limiting how much sodium you eat can also help.