Pleural effusion

Pleural effusion is a collection of fluid around your lungs. Your provider has to get rid of this fluid with medicine or a procedure. Also, they need to diagnose and treat the condition that caused pleural effusion. Treatments range from medicine to surgery. Pleural effusion can happen more than once. Your outlook depends on what caused it.


Excess fluid collecting between the layers of your pleura is pleural effusion.
Pleural effusion is the buildup of too much fluid between the layers of your pleura around your lungs.

What is pleural effusion?

Pleural effusion, which some people call “water on the lungs,” is the buildup of excess fluid between the layers of the pleura outside your lungs. The pleura are thin membranes that line your lungs and the inside of your chest cavity.

Normally, everyone has a small amount of fluid in their pleura. This fluid acts as a natural lubricant and makes it easier for your lungs to move when you breathe. But with pleural effusion, you have too much fluid around your lungs. This means your body is producing too much of the fluid or not absorbing enough of the fluid it makes.

Types of pleural effusion

Healthcare providers split pleural effusion into two types, depending on the kind of fluid around your lungs.

Excess fluid may be:

  • Protein-poor and watery (transudative). Fluid of this kind comes from cirrhosis or heart failure, for example. This type of pleural effusion happens when there’s an increase in pressure from the fluid.
  • Protein-rich (exudative). Fluid of this kind comes from cancer or an infection, for example. This type of pleural effusion happens because too much fluid is getting through your smallest blood vessels or your lymphatic system isn’t draining enough.

Treatment varies by type and cause.

How common is pleural effusion?

Pleural effusions are very common. Healthcare providers find pleural effusions in about 1.5 million people in the United States each year.


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Symptoms and Causes

What are the symptoms of pleural effusion?

You may have unrelated symptoms due to the disease or condition that caused pleural effusion. Pleural effusion symptoms include:

  • Chest pain. Coughing or deep breathing makes it worse.
  • Dyspnea (shortness of breath, or difficult, labored breathing).
  • Orthopnea (the inability to breathe easily unless you’re sitting up straight or standing up straight).

Some people with pleural effusion have no symptoms. They find out they have pleural effusion when they have a chest X-ray for another reason.

What causes pleural effusion?

There are many causes of pleural effusion, and some people have more than one.

Depending on the cause, the excess fluid may be either protein-poor (transudative) or protein-rich (exudative). These two categories help providers determine the cause of the pleural effusion. A pulmonary embolism (PE) can fall under either category.

The most common causes of transudative (watery fluid) pleural effusions include:

Common causes of exudative (protein-rich fluid) pleural effusions include:

Less common causes of pleural effusion include:

In some cases, the fluid itself may have malignant (cancerous) cells or may be a direct result of chemotherapy.

What are the risk factors for pleural effusion?

Risk factors for pleural effusion include:

  • Medical conditions that cause it.
  • Tobacco products.
  • Exposure to asbestos.

What are the complications of pleural effusion?

Pleural effusion can lead to:

  • An infection that becomes an abscess.
  • Scarring around the lungs.
  • Damage to your lungs.

Diagnosis and Tests

How is pleural effusion diagnosed?

A provider will ask you about your medical history. They’ll ask what other illnesses you have and when your symptoms started. They’ll do a physical exam, which includes listening to your lungs when you breathe. Next, they’ll order tests.

What tests will be done to diagnose pleural effusion?

Healthcare providers use these tests to diagnose and evaluate pleural effusion:

If less invasive tests don’t diagnose pleural effusion, you may need a thoracoscopy. Thoracoscopy is a minimally invasive technique, also known as video-assisted thoracic surgery, or VATS. A provider performs this while you’re under general anesthesia. Thoracoscopy allows them to see and evaluate your pleura. Often, they’ll treat your effusion during the thoracoscopy.


Management and Treatment

How is pleural effusion treated?

Treatment of pleural effusion focuses on getting the excess fluid out and keeping it from collecting again. Providers choose pleural effusion treatment based on the underlying condition and whether the effusion is making it hard for you to breathe.


Providers use diuretics and other heart failure medications to treat pleural effusion from congestive heart failure or other medical causes. Some people need antibiotics. For a malignant effusion, you may also need treatment with chemotherapy, radiation therapy or a medication infusion within your chest.


A provider can use therapeutic thoracentesis or a chest tube to drain a pleural effusion that’s causing respiratory symptoms.

Even with drainage, you may have pleural effusions that are hard to control or that come back due to a malignancy. In this case, a provider puts a sclerosing agent (a type of drug that purposely creates scarring) into your pleural cavity through a chest tube. This causes fibrosis (excessive fibrous tissue) of the pleura (pleural sclerosis). This is 50% successful in preventing pleural effusions from happening again.


You may need surgery if drainage or pleural sclerosis don’t work. Your surgeon will carefully evaluate you and discuss the possible risks and benefits of surgical pleural effusion treatments.

The two types of surgery include:

  • Video-assisted thoracoscopic surgery (VATS). This minimally invasive approach uses one to three small (half-inch) incisions (cuts) in your chest. VATS can manage pleural effusions that are difficult to drain or that come back because of a tumor. A provider can insert sterile talc or an antibiotic during surgery to prevent fluid from building up again.
  • Thoracotomy (traditional, “open” thoracic surgery). A surgeon performs a thoracotomy through a 6-inch to 8-inch incision in your chest. They use this approach when you have an infection. A thoracotomy removes all of the fibrous tissue and helps clear out the infection from the pleural space. You’ll need chest tubes for two days to two weeks after surgery to keep draining fluid.

Complications/side effects of the treatment

Complications of treatment may include:

How long does it take to recover from this treatment?

You may need to take it easy for two days after a thoracentesis. If you have VATS, you may need to spend a few days in the hospital afterward. After a thoracotomy (open surgery), you’ll probably be in the hospital for a week.


How can I lower my risk of pleural effusion?

You may not be able to avoid the many causes of pleural effusion. But you can lower your risk of pleural effusions in these ways:

  • Avoiding tobacco products.
  • Avoiding asbestos.
  • Sticking to low-salt meals if your provider instructs you to.
  • Taking prescribed diuretics (water pills).
  • Limiting fluid intake if your provider tells you to.

Outlook / Prognosis

What can I expect if I have pleural effusion?

You may have follow-up X-rays after you receive treatment. Your provider will want to make sure the treatment worked well. You’ll also need treatment for the medical condition that caused pleural effusion.

The seriousness of your condition depends on:

  • The main cause of pleural effusion.
  • If it’s affecting your breathing.
  • If it responds well to treatment.

Outlook for pleural effusion

The outlook or prognosis varies depending on what caused your pleural effusion and what other conditions you have. For some people, pleural effusion treatment is successful. But pleural effusions can happen again. The outlook isn’t good when you have a pleural effusion from cancer. It’s also not good if you don’t get treatment for pleural effusion.

Living With

How do I take care of myself?

Some medical conditions that cause pleural effusion require long-term treatment. Be sure to talk with your provider about the best treatment for your chronic (long-term) condition. Then, stick to the treatment plan.

When should I see my healthcare provider?

Go to all your follow-up appointments to manage your chronic condition. Get immediate help if you’re having trouble breathing.

What questions should I ask my doctor?

You may want to ask your provider:

  • What caused my pleural effusion?
  • How often do I need follow-up appointments with you?
  • What are my chances of getting a pleural effusion again?
  • What are the long-term effects of my pleural effusion?

A note from Cleveland Clinic

So you have pleural effusion and you may not have even had symptoms. Diagnosing the cause of it is key. Once your provider knows the cause, they can take steps to treat it. Answering their questions can help them rule out some potential causes. It can be scary when you have trouble breathing, so don’t be afraid to ask questions about anything you want to understand better.


Medically Reviewed

Last reviewed by a Cleveland Clinic medical professional on 01/18/2023.

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