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Oedema is fluid retention. Oedema can be most easily seen around the feet and ankles, often after standing for long periods (peripheral oedema). After lying down for a while, the skin around the eyes may look puffy and swollen. In severe cases, oedema can also collect in the lungs causing shortness of breath.

Mild oedema is common and usually harmless. Oedema may be due to medication, allergies or more serious underlying disease.

Often no particular cause will be found. The most common causes are mentioned below.

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What is oedema?

Oedema is a collection of fluid in the spaces between cells of the body. Fluid leaks out of damaged cells. The fluid cannot be simply drained with a needle.

Types of oedema

Types of oedema include:

  • Idiopathic - no known cause. Seven out of ten women will have this at times.

  • Localised - fluid retention in a particular part of the body. It is usually due to injury or an allergic reaction.

  • Generalised - affects the whole body. It usually causes puffy ankles after standing and puffy eyes after lying down for a while. This may be due to an underlying heart condition.

  • Cerebral oedema - fluid on the brain, usually due to infection (meningitis) or a condition affecting the brain itself (stroke or brain tumour).

  • Pulmonary oedema - fluid on the lungs, usually due to heart disease.

  • Lymphoedema - a build-up of lymph fluid when lymph channels are damaged - eg, after breast cancer surgery. The lymphatic system drains fluid from more distant parts of the body eg, feet or hands. If the system is damaged (usually by surgery to remove cancer) then the drainage is less effective and oedema develops in the part of the body affected by the damage.

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What causes oedema?

Fluid retention (oedema) may be caused by many different conditions. Oedema may be due to spending a long time sitting or having to stay in bed (immobility). Varicose veins and pregnancy are also common causes of oedema. Oedema may also be caused by more serious conditions such as congestive heart failure, liver disease or kidney disease.

No known cause (idiopathic)

Idiopathic oedema is the term for fluid retention which is not caused by a known medical condition. It is most common in women and can sometimes get worse with age. It tends to be worse in hot weather and can develop/get worse during aeroplane flights. Although there is no cure for idiopathic oedema, having a healthy diet which is low in salt can make a significant difference. Reducing alcohol and caffeine can help. Drinking more water actually helps - even though this feels counter-intuitive, there is lots of evidence that drinking between two and three litres of water a day helps reduce oedema.

If overweight, losing weight can help to improve the oedema. Avoiding long periods of standing can also help. Regular exercise is very useful to encourage oedema to lessen. Tight clothes tend to make oedema worse but support stockings can be useful, particularly if having to stand for long periods.

Heart failure

An excess collection of watery fluid in the lungs (pulmonary oedema) is often caused by heart failure.

When the heart is unable to pump blood to the body efficiently, the amount of blood staying in the veins that take blood through the lungs to the left side of the heart increases. As the pressure in these blood vessels increases, fluid is pushed into the alveoli in the lungs. The fluid collects in the many air sacs (alveoli) of the lungs, making it difficult to breathe. This fluid reduces normal oxygen movement through the lungs.


Angio-oedema is a condition that can cause swelling of the deeper layers of the skin. These include the dermis and subcutaneous tissues. It also affects the tissues just under the lining of the airways, mouth and gut (the submucosal tissues).

In most cases there is no known cause and it is not clear why it occurs. This is called idiopathic angio-oedema. Although the cause is not clear, in up to half of cases there is a link to an autoimmune disorder. These include chronic urticaria, systemic lupus erythematosus (SLE) or having an underactive thyroid gland (thyroiditis, hypothyroidism). In some cases there are known triggers that can cause the release of histamine, which leads to tissue swelling of angio-oedema. These include allergic reactions.

Nephrotic syndrome

This is a condition where the kidneys start to leak protein, usually due to kidney disease. This causes symptoms including oedema around the eyes and of the feet and legs, frothy urine, loss of appetite and tiredness. It can be tested for with urine tests and blood tests.

Other possible causes of oedema include anaemia, pregnancy and some kidney diseases. A blood clot in a leg (deep vein thrombosis) can make the leg (with the blood clot) swell.

At a medical assessment for oedema, the important questions will be when the oedema started, how long it lasted for and whether there are any other symptoms, such as shortness of breath or pain. It is important to mention any new medication, including medications bought over-the-counter. An examination of the lungs, heart and blood pressure as well as the oedematous (swollen) area will usually be performed. Urine tests, blood tests, chest x-rays and further heart tests such as a ECG (heart tracing) or an echocardiogram (ultrasound scan of the heart) may be advised.

Oedema treatment

Treatment will depend on the likely cause of the fluid retention (oedema). . Treatments include:

Diuretics ("water pills") have often historically been used to manage the symptoms of oedema. They are very useful in oedema caused by heart failure as they help the heart to pump more effectively. However, diuretics can affect kidney function and make it worse. They should not be used in idiopathic oedema. Counter-intuitively, drinking more water helps reduce idiopathic oedema as the body tries to store water if it does not have enough, hence making oedema worse. There is evidence that using diuretics in idiopathic oedema actually causes worsening of the oedema over time.

How can I get rid of oedema fast?

There is no one-size-fits-all solution and no quick fix. Mild oedema (particularly of the legs and ankles) is often the result of lack of exercise so addressing these issues will help. Warm weather often makes the oedema worse. However, persistent oedema may need assessment by a clinician to detect the underlying cause .

How can I treat itching?

Itching with oedema can be due to several causes.

  • Mechanical stretching of the skin due to fluid retention can cause a local disturbance which results in itching. This usually settles once the oedema is treated.

  • Angio-oedema is often treated with antihistamine tablets and steroid tablets.

  • Varicose veins can cause a combination of oedema and an itchy rash known as varicose eczema. Making sure that the legs are raised when sitting down, keeping active and using moisturising cream regularly all can help. Steroid ointments are occasionally prescribed if the rash becomes very itchy.

What should you do next?

Urgent medical attention should be sought if experiencing severe shortness of breath or chest pain. Mild puffiness of the ankles that gets better overnight after lying down may not need any treatment but medical attention should still be sought to find out if there is an underlying cause.

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Who is affected by oedema?

Women are more prone than men to fluid retention (oedema). Female hormones (progesterone) tend to cause fluid retention so some women notice puffier ankles just before a period.

Oedema may occur for the first time at any age. Older people are more likely to develop oedema as they often sit for longer periods of time. Sedentary people of any age are more likely to develop oedema. Older people are more likely to have underlying heart or kidney conditions that may cause oedema.

For more information, see the separate leaflet called Swollen Legs.

Can oedema be prevented?

Any underlying cause of the fluid retention (oedema) should be addressed if possible. Idiopathic oedema has no specific cause and is very common.

What is the outlook (prognosis)?

This depends on the underlying cause. Oedema can be dangerous if untreated and if it is due to a serious underlying cause such as heart failure.

Further reading and references

Article history

The information on this page is written and peer reviewed by qualified clinicians.

  • Next review due: 11 Jul 2028
  • 13 Jul 2023 | Latest version

    Last updated by

    Dr Pippa Vincent, MRCGP

    Peer reviewed by

    Dr Colin Tidy, MRCGP
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