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GlossarySuccess Chemistry Staff


Edema refers to the increased accumulation of fluid (water, lymph) in the tissue of the body, outside of cells and blood vessels. Normally, about two-thirds of body water is in cells, while the remaining third is made up of tissues (25 percent) and vessels (8 percent). In edema, this ratio shifts in favor of the tissue.

The Short version:

  • The causes of edema may vary.

  • Edema, depending on its cause, can be divided into different forms.

  • Symptoms of water retention in the tissues are swelling.

  • The treatment of edema depends on the underlying disease.

Edema can occur in a specific location, for example, only on a lower leg or the whole body. From a temporal perspective, the fluid can accumulate very suddenly (acute), repeatedly (relapsing) or permanently (chronically)

How does edema develop?

The causes of edema can be very different and still lead to the same appearance. Edema may be due to the following factors:

  • an increase in pressure in the capillaries (the smallest blood vessels in the body)

  • a reduced concentration of albumin (a protein produced by the liver that, among other things, binds water)

  • a combination of these two mechanisms

  • damage to the vessel shell

The following diseases and medicines can lead to such changes:

  • Heart failure (right heart failure, left heart failure)

  • Renal dysfunction, renal insufficiency

  • cirrhosis

  • Venous insufficiency (chronic venous insufficiency, CVI) on the leg

  • Malnutrition or digestive disorders (inflammatory bowel disease, celiac disease )

  • allergies

  • A deposit

  • Hypothyroidism

  • Disorders of the lymph

  • Hormonal disorders/changes (hyperaldosteronism, Cushing's syndrome, pregnancy, before menstruation)

  • Medicines (non-steroidal anti-inflammatory drugs, antihypertensives, estrogens)

Sometimes no identifiable cause can be determined. After excluding all other causes, one then speaks of idiopathic edema.

Special forms of edema

There are special forms of edema, which are usually differentiated by the cause:

brain edema

Increase in the volume and pressure in the brain. The causes of this increase may be different (including tumors, bleeding, meningitis complications)

eyelid edema

Swelling of the eyelids. Can be caused by insect bites, eye inflammation, and allergies.


Edema due to weak lymphatic vessels. Most severe swelling, hardly noticeable in late stages. It is differentiated between the primary (innate) and secondary (acquired, among other things by tumors, inflammations, operations) lymphedema.

Angio-edema or Quincke's edema

Is caused by an allergy. Swelling of the facial area (lips, eyelids) and gastrointestinal tract is typical. May also occur in inheritable form.

Reinke's edema

Fluid accumulation in the vocal folds by long-term stimuli such as smoking, particulate matter or overstressing the vocal cords.


Pregnancy can lead to water retention. These may be physiological ("normal"), but also due to kidney disease or pregnancy-related hypertension.


Water retention often under the skin due to hypothyroidism, typically on the tibia.

hunger edema

Edema caused by a diet-related lack of protein (eg fasting, low-protein diet, zero diet), which manifests itself above all as ascites (edema in the abdomen).

pulmonary edema

Water accumulation in the lungs, which is often caused by left heart failure. May also be caused by other causes, such as infections, medications, toxins, ingestion of fluids into the respiratory tract.

macular edema

Water retention in the retina in the area of the macula. The macula, also called a yellow spot, is the area of the sharpest vision.


Water retention in the mucous membrane of the larynx, which can also affect the vocal folds. Medications, infections, allergies, and injuries can cause glottic edema. Generalized edema of the unborn child, which may be due to various diseases (maternal and child blood group incompatibility, heart defects, infections).

nuchal translucency

From the 11th to the 14th week of pregnancy the unborn child has edema in the neck area that is completely normal up to a certain size. An enlargement is associated with an increased likelihood of chromosome disorders or malformations.


Atypical symmetric accumulation of adipose tissue laterally on the hips and thighs and upper arms, later also on the lower legs, forearms, and neck; colloquially called "saddle pants syndrome". Occurs mainly in women. The primary cause is damage to the lymphatic system.

What symptoms cause edema?

Edema is swellings that are either confined to one area or can occur all over the body.

Depending on the cause of the edema, there are different types of swelling and additional symptoms:

right heart failure

Bilateral swelling of the feet, ankles and later on the shins. Water retention in the abdomen (ascites) possible. In bedridden patients, fluid accumulation may also occur around the sacrum in accordance with gravity.

left ventricular failure

Often the cause of pulmonary edema. Shortness of breath, rapid pulse, coughing up of foamy mucus, partly with bloody fluid. The skin may be pale and bluish due to the lack of oxygen while rattling breath sounds.


Typical for liver cirrhosis is in addition to generalized swelling water retention in the stomach (ascites).

Venous insufficiency, thrombosis (blood clots)

Unilateral swelling of the lower leg and/or ankle/foot.

Renal dysfunction

Often swelling in the face and around the eyes. If the disease progresses, fluid in the abdomen (ascites) or in the chest (pulmonary edema) may accumulate.


Swelling usually on the ankles, ankle, and legs. They can harden, which is often associated with a feeling of tension and pain. The toes are swollen ("box toe"). In secondary lymphoedema (due to tumors or infections) spread from the trunk towards the extremities.

Allergy (angiogenic or quincke edema)

Common in the facial area (lips, eyelids) and gastrointestinal tract. Tension and itching on the affected areas.

How do doctors make a diagnosis?

Edema is usually recognized by a good "clinical look". Together with a thorough anamnesis and a manual examination of the swelling, it is then usually possible to clarify the causes of the edema.

The doctor examines where the edema occurs, what the skin looks like and what the swelling is like: is the edema compressible, painful, does it form dents?

Of particular importance is the questions about medications taken and long-standing illnesses of internal organs and injuries.

In case of ambiguity, laboratory examinations (blood, urine) and examinations with equipment (eg ultrasound, X-ray, magnetic resonance) can be added.

How is edema treated?

The treatment of edema depends on the underlying disease. Apart from angioedema and acute pulmonary edema - two life-threatening forms of edema that require immediate treatment - fluid retention should not be too rapid, leaving enough room for treatment.

Generally, generalized edema is usually treated with a diuretic and a low-fluid and low-salt diet. Weight, kidney values, urinary excretion and electrolytes should be kept in mind. If the cause is known, the treatment depends on the underlying disease:

underlying diseasetreatment methodsright heart failureDiuretic, possibly nitrates (preload reduction)left ventricular failureDiuretic, ACE inhibitors, possibly aldosterone antagonists, beta blockerscirrhosisdiureticThrombosis (blood clots)Compression stockings, elevation, dissolution (lysis) or surgical removal of the clot venous insufficiencyVariceal surgeryAllergy (angiogenic or quincke edema)Antihistamines & SteroidsRenal dysfunctionDiuretic (loop diuretics)

Treatment for lymphatic disorders

  • Complex physical decongestive therapy (KPE): lymphatic drainage , compression therapy  with compression stockings or replacement bandages, decongestant movement and respiratory therapy, skin care

  • Physiotherapy, apparatus intermittent compression, thermotherapy

  • Medications are used to treat the complications: antibiotics, antihistamines, cortisone, diuretics under certain circumstances.

  • In the operative treatment, an interrupted lymphatic system can be restored, the lymph can be derived by other means (establishing a connection between the lymph and veins) and diseased tissue can be removed.

  • Clinical-psychological treatment with possibility of continuation outside of hospitalization

Prognosis and disease course of edema

The prognosis depends very much on the underlying disease. If the underlying disease can be treated well, usually the edema disappears again.