Edema is swelling that occurs when too much fluid becomes trapped in the tissues of the body, particularly the skin.

There are different causes and types of edema. Pulmonary edema, for example, affects the lungs, while pedal edema causes swelling in the feet.

Edema usually starts slowly, but onset can be sudden. It is a common problem, but it can also be the sign of a serious condition.

This MNT Knowledge Center article will explain what edema is and how to recognize it, as as the different types and treatments of edema. The article will also look at possible complications of the condition.

Fast facts on edema

Here are some key points about edema. More detail is in the main article.

-Edema happens when excess fluid stays within the body’s tissues.
-There is usually an underlying disease or condition.
-Symptoms depend on the cause, and they normally develop gradually.
-Medications are available to treat edema.

What is edema?

Edema refers to swelling and puffiness in different areas of the body.

It most often occurs in the skin, especially on the hands, arms, ankles, legs, and feet. However, it can also affect the muscles, bowels, lungs, eyes, and brain.

The condition mainly occurs in older adults and women who are pregnant, but anyone can experience edema.

Symptoms

Symptoms depend on the underlying cause, but swelling, tightness, and pain are common.

A person with edema may notice:

-swollen, stretched, and shiny skin
-skin that retains a dimple after being pressed for a few seconds
-puffiness of the ankles, face, or eyes
-aching body parts and stiff joints
-weight gain or loss
-fuller hand and neck veins
-higher pulse rate and blood pressure
-headache
-abdominal pain
-changes in bowel habits
-nausea and vomiting
-confusion and lethargy
-visual abnormalities

Symptoms depend on the underlying cause, the type of edema, and where the edema is located.

Treatment

Treatment will depend on the cause of edema.

Diuretics are a type of medication. They help get rid of excess fluid by increasing the rate of urine production by the kidneys. Different types work in different ways.

A doctor will recommend a specific treatment for macular edema, pulmonary edema, and other types of edema.

Alternative remedies

Some self-care techniques can help prevent or reduce edema.

These include:

-cutting down salt consumption
-losing weight, if appropriate
-doing regular exercise
-raising the legs when possible to improve circulation
-wearing supporting stockings, which are available to purchase online
-not sitting or standing still for too long
-getting up and walking about regularly when traveling
-avoiding extremes of temperature, such as hot baths, showers, and saunas
-dressing warmly in cold weather

A masseuse or physical therapist may help remove the fluid by stroking firmly in the direction of the heart.

Oxygen may be used to treat some kinds of edema. An individual with cardiogenic pulmonary edema may need additional oxygen if they have difficulty taking in enough oxygen.

Oxygen delivered through the nose may improve poor vision caused by diabetic macular edema.

Hyperbaric oxygen therapy (HBOT) has been found to increase the risk of pulmonary edema.

Types

There are many types of edema. Each one can indicate a range of further health conditions. Here are some types.

Peripheral edema: This affects the feet ankles, legs, hands, and arms. Signs include swelling, puffiness, and difficulty moving a part of the body.

Pulmonary edema: Excess fluid collects in the lungs, making breathing difficult. This can result from either congestive heart failure or acute lung injury. It is a serious condition, it can be a medical emergency, and it can lead to respiratory failure and death.

Cerebral edema: This occurs in the brain. It can happen for a range of reasons, many of which are potentially life-threatening. Symptoms include headache, neck pain or stiffness, whole or partial vision loss, change in consciousness or mental state, nausea, vomiting, and dizziness.

Macular edema: This is a serious complication of diabetic retinopathy. Swelling occurs in the macula, the part of the eye that enables detailed, central vision. The person may notice changes to their central vision and how they see colors.

Edema can occur in other locations as well, but those mentioned above are the most common. It can indicate one of many serious health conditions. It is important to check with a doctor if you are concerned about any kind of swelling.

Causes

Edema can result from circulatory problems, infection, tissue death, malnutrition, kidney disease, total body fluid overload, and electrolyte problems.

There are many possible causes of edema, including:

Heart failure

If one or both of the lower chambers of the heart cannot pump blood properly, the blood can accumulate in the limbs, causing edema.

Kidney disease or kidney damage

A person with a kidney disorder may not be able to eliminate enough fluid and sodium from the blood. This puts pressure on the blood vessels, which causes some of the liquid to leak out. Swelling can occur around the legs and eyes.

Damage to the glomeruli, the capillaries in the kidneys that filter waste and excess fluids from the blood, can result in nephrotic syndrome. One symptom of this is a low level of the protein albumin in the blood. This can lead to edema.

Liver disease

Cirrhosis affects liver function. It can lead to changes in the secretion of hormones and fluid-regulating chemicals and reduced protein production. This causes fluid to leak out of blood vessels into surrounding tissue.

Cirrhosis also increases pressure within the portal vein, the large vein that carries blood from the intestines, spleen, and pancreas, into the liver. Edema can result in the legs and the abdominal cavity.

Certain medications

Some medications increase the risk:

-vasodilators, or drugs that open blood vessels
-calcium channel blockers
-non-steroidal anti-inflammatory drugs (NSAIDs)
-estrogens
-some chemotherapy drugs
-some diabetes drugs, such as thiazolidinediones (TZDs)

Pregnancy

During pregnancy, the body releases hormones that encourage fluid retention, and a woman tends to retain more sodium and water than usual. The face, hands, lower limbs, and feet may swell.

When a woman is resting in a reclined position during pregnancy, the enlarged uterus can press on a vein known as the inferior vena cava. This can obstruct the femoral veins, leading to edema.

During pregnancy, the blood clots more easily. This can increase the risk of deep venous thrombosis (DVT), another cause of edema.

Eclampsia, which results from pregnancy-induced hypertension, or high blood pressure, can also cause edema.

Dietary factors

A number of dietary factors impact the risk of edema, such as:

consuming too much salt, in people who are susceptible to developing edema
malnutrition, where edema can result from low protein levels in the blood
a low consumption of vitamin B 1, B 6, and B 5

Diabetes

Complications of diabetes include:

cardiovascular disease
acute renal failure
acute liver failure
protein-losing enteropathy, an intestinal condition that causes protein loss
These, and certain medications for diabetes, can result in edema.

Diabetic macular edema is the swelling of the retina in diabetes.

Conditions affecting the brain

Some causes of swelling in the brain include:

Head injury: A blow to the head may result in an accumulation of fluids in the brain.

Stroke: A major stroke can result in brain swelling.

Brain tumor: A brain tumor will accumulate water around itself, especially as it builds new blood vessels.

Allergies

Some foods and insect bites may cause edema of the face or skin in people who are allergic or sensitive to them. Severe swelling can be a sign of anaphylaxis. Swelling in the throat can close a person’s airway, so they cannot breathe. This is a medical emergency.

Problems with the extremities

A blood clot: Any blockage, such as a clot in a vein, can prevent blood from flowing. As pressure increases in the vein, fluids start to leak into the surrounding tissue, causing edema.

Varicose veins: These usually occur because valves become damaged. Pressure increases in the veins, and they start to bulge. The pressure also increases the risk of fluids leaking into the surrounding tissue.

A cyst, growth, or tumor: Any lump can cause edema if it presses against a lymph duct or a vein. As pressure builds up, fluids can leak into surrounding tissue.

Lymphedema: The lymphatic system helps remove excess fluid from tissues. Any damage to this system, such as surgery, infection, or tumor, can result in edema.

Miscellaneous conditions

Prolonged immobility: People who are immobilized for a long time can develop edema in their skin. This can be due both to fluid pooling in gravity dependent areas and the release of antidiuretic hormone from the pituitary.

High altitude: This, combined with physical exertion, can increase the risk. Acute mountain sickness can lead to high-altitude pulmonary edema or high-altitude cerebral edema.

Burns and sunburn: The skin reacts to a burn by retaining fluid. This causes localized swelling.

Infection or inflammation: Any tissue that is infected or inflamed can become swollen. This is usually most noticeable in the skin.

Menstruation and pre-menstruation: Hormone levels fluctuate during the menstrual cycle. During the days before menstrual bleeding, levels of progesterone are lower, and this may cause fluid retention.

The contraceptive pill: Any medication that includes estrogen can cause fluid retention. It is not uncommon for women to put on weight when they first start using the pill.

Menopause: Around menopause, hormone fluctuations can cause fluid retention. Hormone replacement therapy (HRT) can also trigger edema.

Thyroid disease: Hormonal imbalances associated with thyroid problems can lead to edema.

Complications

Untreated edema can lead to:

-painful swelling, with pain that gets worse
-stiffness and difficulty walking
-stretched and itchy skin
-infection in the area of swelling
-scarring between the layers of tissue
-poor blood circulation
-loss of elasticity in arteries, veins, and joints
-ulcerats on the skin

Any underlying disease or condition needs treatment to prevent it from becoming more serious.

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