Oedema is the medical term for fluid retention in the body. It was formerly known as dropsy or hydropsy and most commonly causes swelling of the hands, arms, feet, ankles and legs. The condition is called edema in American English.
Oedema occurs when there is a build-up of fluid (mainly water) in the body's tissues, causing swelling to occur in the affected area.
As well as swelling or puffiness of the skin, oedema can cause:
- skin discolouration
- fluid-filled areas of skin that temporarily hold the imprint of your finger when pressed (known as pitting oedema)
- aching, tender limbs
- stiff joints
- weight gain or weight loss
- raised blood pressure and pulse rate
Oedema is often a symptom of an underlying condition. It can also be caused by a variety of factors such as high salt intake in the diet or being immobile for long periods of time (see below).
A common cause of fluid build-up in the tissues is a condition called lymphoedema. It occurs when the lymphatic system is damaged or disrupted.
The lymphatic system is a series of glands (lymph nodes) throughout the body. They are connected by a network of vessels, much like blood vessels. Fluid surrounding the body tissues normally drains from the tissues into the nearby lymph vessels to be transported away and emptied back into the blood.
If the lymphatic vessels are not working properly, for example because they are blocked, excess fluid cannot be reabsorbed and builds up in the tissues.
Oedema can also be caused by the following conditions or treatments:
- kidney disease
- heart failure
- chronic lung disease
- thyroid disease
- liver disease
- medication, such as corticosteroids or medicine for high blood pressure
- the contraceptive pill
If it occurs in the leg, the cause may be any of the following:
- a blood clot
- varicose veins
- a growth or cyst
Oedema may also result from the following factors:
- a high intake of salt in the diet
- sitting or standing still for long periods of time
- hot weather
- exposure to high altitudes
- burns to the skin
When doctors cannot find an obvious cause for oedema, it is know as idiopathic oedema.
Where it occurs
Oedema can occur in any tissue in the body, but it most commonly affects the hands, arms, feet, ankles and legs (this is known as peripheral oedema).
Other types of oedema include cerebral oedema (affecting the brain), pulmonary oedema (affecting the lungs) and macular oedema (affecting the eyes).
Oedema is usually cured by diagnosing and treating the underlying condition causing the imbalance of fluids in your body.
Your GP may recommend some simple self-care techniques to reduce the build-up of fluid in your body, such as reducing your salt intake, losing weight (if you are overweight) and raising your legs three to four times a day to improve your circulation.
Drugs called diuretics may be prescribed to reduce the build-up of fluid in your tissues. Diuretics increase the amount you urinate and are not suitable if you are pregnant or have weakened valves in the veins of your legs.