What causes edema? Diagnosis, prevention, and treatment

Medically reviewed by Leslie Greenberg, MD
Board-Certified Family Physician
Updated Jun 10, 2024  •  Published Aug 7, 2023
Fact Checked
In this article:

Overview: What is edema?

Edema is swelling caused by excess fluid in the body’s tissues. Usually, the body keeps fluids balanced between the blood, cells, and the spaces between cells. Fluid in the bloodstream passes into the tissues through small blood vessel walls. Fluids in the tissues circulate in and out of cells and back into the bloodstream through the lymphatic system. Excess fluid is eliminated primarily through the kidneys, though other organs are also involved. Edema occurs when any part of this mechanism—the circulatory system, the lymphatic system, or the kidneys—doesn’t work optimally, so fluid builds up in the spaces within soft tissues. Excess fluid can collect anywhere on the body, but it usually builds up in the feet, lower legs, and lower arms due to gravity. Healthcare professionals call this peripheral edema. Sometimes, only one part of the body or organ is affected, such as the lungs, brain, or eyes. These cases can be severe and life-threatening. 

RELATED: What causes swollen legs from the knee down? Related conditions and treatments

Key takeaways:

  • Edema is a common health condition that can affect anyone regardless of age, sex, race, or ethnicity. 

  • Edema is caused by heart failure, blood vessel problems, lymphatic system problems, kidney disease, liver disease, diabetes, thyroid disease, pregnancy, menopause, allergies, infections, injuries, medication side effects, prolonged immobility, high altitude, and diet.

  • Risk factors for edema include older age, female sex, low income, excess weight, hypertension, diabetes, a sedentary lifestyle, chronic illness, and limited mobility.

  • Symptoms of edema include swelling, puffiness, shiny and stretched skin, mild pain, leg heaviness, difficulty walking, and abdominal distension. Dimple formation caused by pressure is a telltale sign of edema. Excessive fluid in organs like the brain, eyes, or lungs will cause symptoms such as trouble breathing, coughing, mental changes, unconsciousness, and vision changes. 

  • Edema usually requires a medical diagnosis.

  • Edema generally does require treatment. Depending on the cause, it can sometimes resolve with or without treatment in a few days. More serious conditions that cause edema can be managed with treatment, and the swelling may improve, but the edema may likely be lifelong.

  • Treating edema may include lifestyle changes, dietary changes, compression stockings, diuretics, elevation of the legs, and treatments for the underlying medical condition.

  • Edema is partly preventable with regular physical activity and a healthy diet. Some causes of edema, such as heart failure, need chronic management to help rid the body of excessive fluid.

  • Use coupons for edema treatments, like Lasix (furosemide), torsemide, and hydrochlorothiazide, to save up to 80%.

What causes edema?

Edema is commonly due to problems with veins, water retention, increased flow of water out of the blood vessels, or problems with the circulation of fluids in the body’s tissues. 

One of the most common causes of edema is various blood vein problems that cause high blood pressure in the veins. These venous problems can be caused by:

Another common edema cause is retaining water. There’s just too much fluid in the body. Causes of water retention include:

Edema can also be caused when something goes wrong with the mechanism by which fluids pass from the bloodstream into the surrounding tissues. Causes include:

  • Malnutrition or poor diet (low protein)

  • Vitamin deficiencies

  • Burns

  • Allergic reactions (angioedema)

  • Injuries

  • Sepsis

  • Prolonged immobility

  • High altitude

  • Severe kidney disease (nephrotic syndrome)

  • Preeclampsia or eclampsia

  • Liver failure or liver cirrhosis

Sometimes the lymphatic system is blocked, so it cannot return fluids to the bloodstream. Healthcare providers call this lymphedema. Common causes are:

  • Lymph node cancer

  • Lymph node surgery

  • A parasite (worm) infection of the lymphatic vessels called filariasis 

Medications that are most likely to cause edema include:

Other drugs like nonsteroidal anti-inflammatory drugs (NSAIDs) or some types of antidepressants or diabetes medications can cause edema, but the probability is low. 

Risk factors for edema

Because there are so many edema causes, there are many risk factors because each cause of edema has its risk factors. The most common risk factors for edema include:

  • Older age

  • Female sex

  • Low income

  • Obesity

  • High blood pressure

  • Diabetes

  • Sedentary lifestyle

  • Limited mobility

  • Chronic illness

Is edema serious? When to see a doctor

Edema should be evaluated by a doctor. Look for symptoms such as swelling, stretched skin, shiny skin, or dimples that stay in place after pushing on the skin. The underlying cause may be a serious health problems like heart disease, kidney disease, or liver problems. Even if the cause isn’t serious, untreated peripheral edema can lead to complications such as skin ulcers, difficulty walking, itchy skin, stiffness, and an increased risk of infections.

When edema occurs in the brain, the lungs, or the eyes, emergency medical help is needed. Look for symptoms of shortness of breath, heartbeat changes, chest pain, confusion, loss of consciousness, or vision changes.

How is edema diagnosed?

A physician diagnoses the cause of edema through a medical history, physical exam, and other tests or imaging. There are many causes of edema, so expect the clinician to ask many questions. Be prepared to talk about other symptoms, current medical conditions, medications being taken, and activities. 

The clinician will look closely at any swollen areas during the physical exam. The physical characteristics of the swelling provide clues about the possible cause. The swelling may be localized (focal edema) or on both sides of the body (bilateral edema), or may be throughout the body (generalized edema). The diagnostician will also push a thumb or finger into the swollen area. This may leave a dimple (pitting edema), the skin may be firm, and no impression is left (non-pitting edema). Pitting often indicates blood vessel problems, heart problems, or kidney problems. Non-pitting edema is characteristic of allergic reactions or lymphatic system problems. However, the clinician will usually perform a thorough physical exam, including listening to the lungs and heart to look for other symptoms that point to a diagnosis.

Depending on the physical exam results, the clinician may order tests or imaging, including blood tests, chest X-rays, ultrasound, or an electrocardiogram (EKG). A specialist usually diagnoses and treats brain, lung, or retina swelling.

Is edema curable?

Many cases of edema resolve spontaneously in a few days or weeks. Some may require treatment, but healthcare providers focus on treating the underlying condition causing edema.

The following therapies are used to treat the most prevalent diseases that result in edema:

The most common treatments to reduce swelling due to edema include:

  • Elevation of the affected area or limb above the heart

  • Regularly scheduled moving or walking

  • Use of compression bandages or support stockings

  • Massaging the swollen area

  • Reducing salt in the diet

Sometimes, a healthcare provider may prescribe a diuretic (“water pill”). This drug increases the body’s elimination of water and helps rid the body of extra fluid.

How to prevent edema

Sometimes, edema is not preventable. People with heart failure, kidney disease, or cirrhosis may live with chronic swelling. Pregnant women may also have to endure extra swelling until the baby is born. However, there are ways to prevent edema that can also help manage the condition when edema cannot be prevented:

  • Reduce salt intake

  • Avoid sitting or lying down for prolonged periods—instead, get up and move regularly which helps the veins of the legs get blood and fluid back to the heart

The best way to prevent edema is to avoid the conditions that cause it. Learn about these medical conditions, such as heart failure, lung problems, liver problems, kidney disease, and venous insufficiency. For instance, one way to help prevent liver cirrhosis is to avoid alcohol and maintain a healthy weight. One effective way to help prevent lung problems is to quit smoking. Venous insufficiency can be partly prevented by regular physical activity and eating a healthy diet.

Most importantly, see a doctor

See a doctor if there’s unexplained swelling or other signs of edema. The extra fluid buildup may be insignificant and improve in a few days but it could also be a sign of a serious condition needing evaluation and treatment. Remember that some types of edema can’t be seen, such as swelling in the brain, the lungs, or the retina. They can only be suspected by the symptoms. Since they are potentially debilitating or life-threatening conditions, they need emergent treatment.

FAQs about edema causes

What causes pulmonary edema?

Pulmonary edema is a buildup of fluid in the lungs. It is commonly due to heart problems, including heart disease, heart attack, irregular heartbeats, and atrial fibrillation. Other possible causes include injury, infections, or shock.

What causes edema in the legs?

Swelling in the legs is called peripheral edema. There are dozens of possible causes of leg swelling. Problems with blood veins in the legs, such as blood clots or weak veins, are common causes of edema. Water retention is another likely cause. It can be due to various reasons, from excessive salt intake to kidney failure. If only one leg is swollen, the probable cause is a lymphatic obstruction or previous vein injury in that leg. It is only possible to know once a clinician makes a diagnosis.

What causes macular edema?

A buildup of fluid in the retina, called macular edema, can lead to permanent vision loss. Like other forms of edema, macular edema has many causes. The most common is damage to the small blood vessels in the retina due to long-standing uncontrolled diabetes. Other causes include blood clots or injuries. Some medications can cause macular edema, including topical epinephrine (for glaucoma), topical latanoprost (for glaucoma), or the breast cancer drug tamoxifen.

What’s next? Additional resources for people with edema

Test and diagnostics

Treatments

Scientific studies and clinical trials

Medically reviewed by Leslie Greenberg, MD
Board-Certified Family Physician

Leslie Greenberg, MD, is a board-certified practicing family physician with more than 25 years of doctoring experience. She was a psychology major at Northwestern University near Chicago, then graduated with an MD from the University of Nevada School of Medicine. She completed her family medicine residency at St. Joseph Hospital in Wichita, Kansas. She has trained more than 350 family medicine resident-physicians, been in private practice, and delivered babies for 22 years.

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