Oedema is a build up of fluid in the body which causes the affected tissue to become swollen.

The swelling can occur in one particular part of the body or may be more general, depending on the cause.

Fluid can accumulate under the skin – most commonly causing swelling of the lower legs and ankles – or in one of the body's internal organs, such as the lungs.

As well as swelling or puffiness of the skin, oedema can also cause:

  • skin discolouration
  • areas of skin that temporarily hold the imprint of your finger when pressed (known as pitting oedema)
  • aching, tender limbs
  • stiff joints
  • weight gain

Types of oedema

Oedema is most common in the feet and ankles. This is known as peripheral oedema.

Other types of oedema include:

  • cerebral oedema – affecting the brain
  • pulmonary oedema – affecting the lungs
  • macular oedema – affecting the eyes

Idiopathic oedema is a term used to describe cases of oedema where a cause can't be found.

Causes of oedema

It's normal to have some swelling in your legs at the end of the day, particularly if you've been sitting or standing for long periods.

Oedema is often a symptom of an underlying health condition. It can occur as a result of the following conditions or treatments:

Immobility and standing for long periods are the two most common causes of oedema in the legs.

Other possible causes include:

Treating oedema

Oedema is often temporary and clears up by itself. For example, if you've been standing up for too long on a hot day, your ankles may swell up until you get the chance to put your feet up and rest.

If oedema doesn't go away by itself, see your GP. They'll try and find out if there's an underlying cause which needs to be treated. This could involve taking medication or following some advice, such as:

  • losing weight (if you're overweight)
  • taking regular exercise, such as walking, swimming or cycling
  • raising your legs three to four times a day to improve your circulation
  • avoiding standing for long periods of time

If an underlying condition is causing the fluid imbalance, it should clear up after the condition has been diagnosed and treated.


Lymphoedema is swelling in the legs caused by a blockage in the lymphatic system, or an inherited condition.

The lymphatic system consists of a series of lymph nodes (glands) connected by a network of vessels (lymphatics), similar to blood vessels.

Fluid surrounding body tissues usually drains into nearby lymph vessels so it can be transported back into the blood. However, if the lymph vessels are blocked, the fluid can't be reabsorbed and will build up in the tissue.

Unlike oedema, lymphoedema is a long-term condition that can cause discomfort, pain and a loss of mobility.

It can't be cured, but it can be controlled using a number of treatments, including:

  • compression stockings
  • skin care
  • lymphatic massage
  • elevation

Read more about lymphoedema.

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Selected links

NHS Direct Wales links

Heart failure

High blood pressure


External links

Sodium test (Lab Tests Online UK)

Idiopathic Oedema (Patient UK)

Health Challenge Wales - Food

Lymphoedema Support Network

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The information on this page has been adapted by NHS Wales from original content supplied by NHS Choices.
Last Updated: 19/09/2016 08:34:57