A pneumothorax (noo-moe-THOR-aks) is a collapsed lung. A pneumothorax occurs when air leaks into the space between your lung and chest wall. This air pushes on the outside of your lung and makes it collapse. Pneumothorax can be a complete lung collapse or a collapse of only a portion of the lung.

A pneumothorax can be caused by a blunt or penetrating chest injury, certain medical procedures, or damage from underlying lung disease. Or it may occur for no obvious reason. Symptoms usually include sudden chest pain and shortness of breath. On some occasions, a collapsed lung can be a life-threatening event.

Treatment for a pneumothorax usually involves inserting a needle or chest tube between the ribs to remove the excess air. However, a small pneumothorax may heal on its own.


The main symptoms of a pneumothorax are sudden chest pain and shortness of breath.

When to see a doctor

These symptoms can be caused by a variety of health problems, and some can be life-threatening, so seek medical attention. If your chest pain is severe or breathing becomes increasingly difficult, get immediate emergency care.


A pneumothorax can be caused by:

  • Chest injury. Any blunt or penetrating injury to your chest can cause lung collapse. Some injuries may happen during physical assaults or car crashes, while others may inadvertently occur during medical procedures that involve the insertion of a needle into the chest.
  • Lung disease. Damaged lung tissue is more likely to collapse. Lung damage can be caused by many types of underlying diseases, including chronic obstructive pulmonary disease (COPD), cystic fibrosis and pneumonia.
  • Ruptured air blisters. Small air blisters (blebs) can develop on the top of the lungs. These blebs sometimes burst — allowing air to leak into the space that surrounds the lungs.
  • Mechanical ventilation. A severe type of pneumothorax can occur in people who need mechanical assistance to breathe. The ventilator can create an imbalance of air pressure within the chest. The lung may collapse completely.

Risk factors

In general, men are far more likely to have a pneumothorax than are women. The type of pneumothorax caused by ruptured air blisters is most likely to occur in people between 20 and 40 years old, especially if the person is very tall and underweight.

Risk factors for a pneumothorax include:

  • Smoking. The risk increases with the length of time and the number of cigarettes smoked, even without emphysema.
  • Genetics. Certain types of pneumothorax appear to run in families.
  • Lung disease. Having an underlying lung disease — especially chronic obstructive pulmonary disease (COPD) — makes a collapsed lung more likely.
  • Mechanical ventilation. People who need mechanical ventilation to assist their breathing are at higher risk of pneumothorax.
  • Previous pneumothorax. Anyone who has had one pneumothorax is at increased risk of another.


Many people who have had one pneumothorax can have another, typically within one to two years of the first.

Sometimes air may continue to leak if the opening in the lung won't close. Surgery may be needed to close the air leak.