Pleural effusion

Key facts

Pleural effusion is a build-up of fluid in the space around your lungs.
Symptoms of a pleural effusion include breathlessness, chest pain and a cough.
There are many possible causes of pleural effusion, such as a chest infection or heart failure.
To diagnose pleural effusion, your doctor may use a needle to remove some fluid from around your lungs to be tested.
Treatment of pleural effusion depends on what is causing it — it may include antibiotics or draining the fluid from around your lungs.

What is a pleural effusion?

Pleural effusion is a build-up of fluid around your lungs. A pleural effusion is not a disease itself — it’s usually a symptom of an underlying condition.

There is a lining on the outside of your lungs and a lining on the inside of your chest wall — these are known as your pleural membranes. It’s normal for the space between these membranes to contain a small amount of fluid called pleural fluid.

This fluid helps your lungs and chest wall move smoothly during breathing. A build-up of fluid in this space is known as a pleural effusion.

Illustration of human lung anatomy with plueral effusion (build-up of fluid in the pleural space). — Plueral effusion (fluid between pleural space).

What are the symptoms of a pleural effusion?

Depending on the cause and the size of the pleural effusion, you might have:

difficulty breathing, which may be worse when lying down
a feeling of pressure in your lungs
a cough
a fever (a temperature of 38℃ or higher)
a sharp pain in your chest, which may get worse when taking a deep breath or coughing

Many people who have a pleural effusion have no symptoms.

CHECK YOUR SYMPTOMS — Use the Symptom Checker and find out if you need to seek medical help.

What causes a pleural effusion?

A pleural effusion develops when more fluid builds up around your lungs than normal.

Pleural effusion can be caused by:

heart failure (a condition where your heart doesn't pump blood as well as it should)
a chest infection , such as pneumonia
cancer
pulmonary embolism (a blood clot in the lungs)
kidney disease
liver cirrhosis (scarring of the liver)
a chest injury

A pleural effusion can also occur after chest surgery or if you are taking certain medicines.

When should I see my doctor?

If you have sudden chest pain or difficulty breathing, call triple zero (000) and ask for an ambulance.

See your doctor if you have symptoms such as:

shortness of breath
chest pain
a cough that does not go away
unexplained weight loss

When to seek urgent care

Seek urgent medical care if you have:

severe or worsening shortness of breath
signs of infection, such as a fever or feeling very unwell
signs of a collapsed lung, such as sudden chest pain or difficulty breathing

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Preparing for an appointment? See our tips on questions to ask your doctor.

How is a pleural effusion diagnosed?

To diagnose a pleural effusion, your doctor will ask about your symptoms and medical history. They will also examine your chest — this may involve listening to your breathing with a stethoscope and tapping on your chest.

Your doctor may organise for you to have other tests such as:

A procedure called a pleural tap can be used to test the fluid around your lungs. This involves using a needle to take a small sample of the fluid. A pleural tap can help confirm the cause of pleural effusion.

FIND A HEALTH SERVICE — The Service Finder can help you find doctors, pharmacies, hospitals and other health services.

How is a pleural effusion treated?

The treatment of pleural effusion depends on:

the cause
how severe it is
your symptoms

If your pleural effusion is small and not causing any symptoms, your doctor might leave it alone while treating the underlying cause, such as heart failure or infection. Treating the cause will often make the pleural effusion disappear.

If your pleural effusion is larger or causing symptoms, your doctor may recommend draining it. The fluid can be drained with a needle inserted through your chest wall. You may need to stay in hospital for a few days after the pleural effusion is drained. You may also benefit from:

oxygen therapy
physiotherapy — this may include breathing exercises and gentle movement

If your pleural effusion keeps coming back, your doctor may recommend a procedure called pleurodesis. A pleurodesis attaches the outside of your lungs to the inside of your chest wall to help stop pleural effusion recurring. Ask your doctor if this procedure is right for you.

What are the complications of a pleural effusion?

If a pleural effusion is left untreated, it can cause complications such as:

scarring of the lining of your lungs
a trapped lung — this is when scar tissue affects how well your lungs work

While complications are rare, draining the fluid from around your lungs can sometimes cause:

pulmonary oedema (a build-up of fluid in the lungs) — this can occur when the pleural effusion is drained too quickly
pneumothorax (air in the pleural space)

Your doctor will take care to avoid these complications as much as possible.

Can a pleural effusion be prevented?

It's possible to help lower your chance of developing a pleural effusion. You can:

get vaccinated against respiratory diseases — this can help prevent pneumonia
quit smoking or vaping
maintain a healthy bodyweight and have a balanced diet — this can help reduce your risk of heart disease
make sure chronic diseases are well managed — this includes diseases such as hypertension (high blood pressure) and diabetes

Resources and support

Visit the Lung Foundation Australia (Opens in new tab) page for more information on:

You can also call the healthdirect helpline on 1800 022 222 (known as NURSE-ON-CALL in Victoria). A registered nurse is available to speak with you 24 hours a day, 7 days a week.