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Oedema: definition, types and causes

Find out about the causes and symptoms of oedema, as well as treatment options to reduce swelling and improve your well-being.

What is oedema?

Oedema is a visible or palpable accumulation of fluid in the body's tissues. This swelling occurs in the interstitial spaces, i.e. the space between tissue cells(1).

Oedema can occur in several parts of the body, such as the legs, arms, face, abdomen, lungs (pulmonary oedema) or even the brain (cerebral oedema), with potentially serious consequences depending on its location(2).

A distinction must be made between oedema of local cause, which occurs in a limited area of the body, and generalised oedema, which affects several areas of the body and is often caused by systemic problems (fluid and sodium retention)(1). For example, a sprained ankle can lead to localised oedema around the ankle and heart failure can lead to fluid retention in the extremities(3).

How does oedema occur?

Oedema can occur for a variety of reasons, including disorders of the lymphatic system, fluid imbalances, heart or kidney problems, venous insufficiency or inflammatory reactions(1).

The mechanism of oedema formation often involves an imbalance between the forces that move fluids in and out of capillaries (small vessels that form a bridge between veins and arteries). When the filtration of liquids (the outflow of liquid from the capillaries) abnormally exceeds the capacity for reabsorption of liquids in these capillaries, the volume of interstitial liquid increases abnormally and causes oedema(4, 5).

What are the main types of oedema?

  • Peripheral oedema

    This is the accumulation of fluid in the legs, feet or arms, often caused by heart, kidney or vein disease. It can also result from chronic venous insufficiency, which prevents the blood from circulating properly and causes a build-up of fluid in the legs (6).

  • Lymphedema

    This type of oedema results from a malfunction of the lymphatic system, preventing lymph from draining properly. This leads to swelling, often of the limbs. Lymphedema can be primary (genetic) or secondary (caused by surgery, infection or trauma) (7).

  • Pulmonary oedema

    In this case, fluid accumulates in the lungs, making it difficult to breathe. This can be caused by heart failure, lung infections or severe allergic reactions. Pulmonary oedema is a medical emergency and requires immediate treatment (8).

  • Cerebral oedema

    This occurs in the brain, often after a head injury, stroke or tumour. This type of oedema can lead to a dangerous increase in intracranial pressure and requires rapid intervention to prevent permanent damage to the brain (9).

  • Inflammatory oedema

    This type is associated with an excessive immune response, such as infection or injury, and is often characterised by redness, pain and localised heat. It can also occur as part of an allergic reaction (10).

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What causes oedema?

There are many possible causes of oedema: circulatory, renal, hepatic and hormonal problems, as well as inflammatory and allergic disorders.

Causes linked to circulatory problems: These include heart failure(the heart does not pump blood efficiently, causing an accumulation of fluid, mainly in the lower limbs) and venous insufficiency, which results from inefficient venous return from the legs to the heart, causing swelling of the tissues.
Deep vein thrombosis, also known as phlebitis, is another example: a clot blocks a vein in the legs, causing localised oedema.

Renal causes: Such as nephrotic syndrome (excessive loss of protein in the urine, which promotes the accumulation of fluid in the tissues) and renal failure (when the kidneys do not filter the blood properly, leading to salt and water retention in the body).

Liver-related causes: e.g. cirrhosis of the liver.

Hormonal and nutritional causes (overproduction of aldosterone, premenstrual syndrome, pregnancy, protein deficiency, etc.).

Lymphatic causes: Including lymphoedema,

Inflammatory and allergic causes: Inflammation due to an injury, infection or insect bite makes the blood vessels more permeable, allowing fluid to pass to the tissues, which can also cause oedema. In an allergic reaction, the histamine released can cause rapid swelling of the affected area.

Medicinal causes: Examples include non-steroidal anti-inflammatory drugs (NSAIDs), corticosteroids, hormones such as oestrogen or oral contraceptives, and certain treatments for high blood pressure.

Pregnancy: Increased blood volume, pressure exerted by the uterus on the pelvic veins and hormonal changes favour water retention and the formation of oedema.

What are the symptoms and signs of oedema?

The symptoms of oedema can vary depending on the underlying cause and the location of the fluid accumulation. Here are a few signs to help guide you(1, 5, 12, 14):

Visible swelling: The main feature of oedema is visible swelling of the affected areas, such as the legs, arms, feet or other parts of the body. This swelling is due to the accumulation of fluid in the tissues. The skin may leave a finger mark after squeezing the limb (cup sign).

Tenderness, pain and/or discomfort: The oedema may cause pain (localised oedema), a feeling of heaviness in the swollen area or heat and therefore discomfort, particularly when the limbs are used or at the end of the day.

Changes to the skin: There may be changes to the temperature, colour and texture of the skin.

Reduced mobility: Severe oedema may limit mobility, especially when the lower limbs are affected. Patients may find it difficult to walk or perform normal movements because of the heaviness and pain.


These symptoms vary depending on the type, severity and cause of the oedema.

How is oedema treated?

Treatment and relief of oedema vary according to the underlying cause and the severity of the fluid accumulation. A qualified healthcare professional will be able to advise you on treatment options. This may include medicinal solutions such as diuretics, or non-medicinal solutions such as wearing compression garments, or physical and manual therapies to improve circulation and reduce swelling.


In cases of venous, lymphatic and traumatic oedema, compression is the treatment of choice.

FAQ about oedema

Our medical team answers the questions you may have.

  • Several therapeutic approaches can be used to deflate oedema, depending on the nature and location of the oedema. These may include medicinal solutions such as diuretics or non-medicinal solutions such as wearing compression garments, physical and manual therapies to improve circulation and reduce swelling, or limb elevation to promote venous and lymphatic return.

  1. Néphrologie, 9ème édition, 2020, Collège universitaire des enseignants de néphrologie, Editions Ellipses
  2. Kallash, M., & Mahan, J. (2020). Mechanisms and management of edema in pediatric nephrotic syndrome. Pediatric Nephrology, 36, 1719 - 1730. https://doi.org/10.1007/s00467-020-04779-x.
  3. Ciccarelli, M., Dawson, D., Falcão-Pires, I., Giacca, M., Hamdani, N., Heymans, S., Hooghiemstra, A., Leeuwis, A., Hermkens, D., Tocchetti, C., Velden, J., Zacchigna, S., & Thum, T. (2021). Reciprocal organ interactions during heart failure: a position paper from the ESC Working Group on Myocardial Function. Cardiovascular Research, 117, 2416 - 2433. https://doi.org/10.1093/cvr/cvab009.
  4. Principes d’anatomie et de physiologie, Tortora, Derrickson, 4ème édition, 2017, édition Deboeck
  5. Patel, H., Skok, C., & Demarco, A. (2022). Peripheral Edema: Evaluation and Management in Primary Care.. American family physician, 106 5, 557-564 .
  6. The Maudsley Practice Guidelines for Physical Health Conditions in Psychiatry. (s. d.). Chapter 7, peripheral oedema, Google Books., https://books.google.fr/books?hl=fr&lr=&id=V0gAEAAAQBAJ&oi=fnd&pg=PA59&dq=what+is+a+peripheral+oedema+%3F&ots=A56XQ5I0v8&sig=bHeWOiWftB7UtdLuprnnFmslcUc#v=onepage&q=what%20is%20a%20peripheral%20oedema%20%3F&f=false
  7. Grada, A., & Phillips, T. (2017). Lymphedema: Pathophysiology and clinical manifestations.. Journal of the American Academy of Dermatology, 77 6, 1009-1020 . https://doi.org/10.1016/j.jaad.2017.03.022.
  8. Barile, M. (2020). Pulmonary Edema: A Pictorial Review of Imaging Manifestations and Current Understanding of Mechanisms of Disease. European Journal of Radiology Open, 7. https://doi.org/10.1016/j.ejro.2020.100274.
  9. Michinaga, S., & Koyama, Y. (2015). Pathogenesis of Brain Edema and Investigation into Anti-Edema Drugs. International Journal of Molecular Sciences, 16, 9949 - 9975. https://doi.org/10.3390/ijms16059949.
  10. Reis, R., Santos, R., Rocha, B., & Lobosco, M. (2019). On the mathematical modeling of inflammatory edema formation. Comput. Math. Appl., 78, 2994-3006. https://doi.org/10.1016/J.CAMWA.2019.03.058.
  11. Koirala A, Pourafshar N, Daneshmand A, Wilcox CS, Mannemuddhu SS, Arora N. Etiology and Management of Edema: A Review. Adv Kidney Dis Health. 2023 Mar;30(2):110-123. doi: 10.1053/j.akdh.2022.12.002. PMID: 36868727.
  12. Trayes KP, Studdiford JS, Pickle S, Tully AS. Edema: diagnosis and management. Am Fam Physician. 2013 Jul 15;88(2):102-10. PMID: 23939641.
  13. Reis, R., Santos, R., Rocha, B., & Lobosco, M. (2019). On the mathematical modeling of inflammatory edema formation. Comput. Math. Appl., 78, 2994-3006. https://doi.org/10.1016/J.CAMWA.2019.03.058.
  14. Besharat, S., Grol-Prokopczyk, H., Gao, S., Feng, C., Akwaa, F., & Gewandter, J. (2021). Peripheral edema: A common and persistent health problem for older Americans. PLoS ONE, 16. https://doi.org/10.1371/journal.pone.0260742.