Treatment may be directed at removing the fluid, preventing it from accumulating again, or addressing the underlying cause of the fluid buildup.

Therapeutic thoracentesis may be done if the fluid collection is large and causing pressure, shortness of breath, or other breathing problems, such as low oxygen levels. Removing the fluid allows the lung to expand, making breathing easier. Treating the underlying cause of the effusion then becomes the goal.

For example, pleural effusions caused by congestive heart failure are treated with diuretics (water pills) and other medications that treat heart failure. Pleural effusions caused by infection are treated with appropriate antibiotics. In people with cancer or infections, the effusion is often treated by using a chest tube for several days to drain the fluid. Chemotherapy, radiation therapy, surgery, or instilling medication into the chest that prevents re-accumulation of fluid after drainage may be used in some cases.

The expected outcome depends upon the underlying disease.

• A lung surrounded by excess fluid for a long time may collapse.
• Pleural fluid that becomes infected may turn into an abscess, called an empyema, which requires prolonged drainage with a chest tube placed into the fluid.
• Pneumothorax (air within the chest cavity) can be a complication of the thoracentesis procedure.

Call your health care provider if you have symptoms of pleural effusion.

Call your provider or go to the emergency room if shortness of breath or difficulty breathing occurs immediately after thoracentesis.