Oedema, also known as dropsy, is the medical term for fluid retention in the body.
The build-up of fluid causes affected tissue to become swollen. The swelling can occur in one particular part of the body – for example, as the result of an injury – or it can be more general.
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 or weight loss
- raised blood pressure and pulse rate
Types of oedema
Oedema can occur anywhere in the body but it's most common in the feet and ankles, where it 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 where doctors are unable to find a cause.
What causes oedema?
Oedema is often a symptom of an underlying health condition. It can occur as a result of 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 (hypertension)
- the contraceptive pill
Oedema that occurs in the leg may be caused by:
Oedema can also sometimes occur as a result of:
- being immobile for long periods
- hot weather
- exposure to high altitudes
- burns to the skin
Lymphoedema is a common cause of fluid build-up in the body's tissues. It occurs when the lymphatic system is damaged or disrupted.
The lymphatic system is a series of glands (lymph nodes) around the body connected by a network of vessels similar to blood vessels. Fluid surrounding body tissues usually drains into nearby lymph vessels so it can be transported away and back into the blood.
However, if the lymphatic vessels are blocked, excess fluid cannot be re-absorbed and will build up in tissue.
Read more about lymphoedema.
How is oedema treated?
Oedema usually clears up when the underlying condition causing the fluid imbalance is diagnosed and treated.
Your doctor may recommend some things you can do yourself to reduce fluid retention, including:
- losing weight (if you are overweight)
- taking regular exercise, such as walking, swimming and cycling
- raising your legs three-to-four times a day to improve your circulation
- avoiding standing for long periods of time
Diuretics are a type of medication that may also be prescribed to help reduce fluid build-up. They work by increasing the amount of urine you produce.
Not everyone can use diuretics and in some cases they can make things worse. They are mainly used to treat people who develop oedema as a result of heart failure.