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Medically reviewed by Last updated on Mar 22, 2023.

What is a Pneumothorax?

Harvard Health Publishing

A pneumothorax is commonly known as a collapsed lung. Normally, the outer surface of the lung sits next to the inner surface of the chest wall. The lung and the chest wall are covered by thin membranes called pleura.

A collapsed lung occurs when air escapes from the lungs or leaks through the chest wall and enters the space between the two membranes (pleural cavity). As air builds up, it causes the nearby lung to collapse.

A collapsed lung may be caused by an injury to the lungs or chest wall, such as:

Occasionally, a lung will collapse without any direct injury to the lung or chest. This is called a spontaneous pneumothorax. This is more likely to happen in people with lung disease.

It is particularly common in emphysema, which causes air-filled sacs, called blebs, to form. When one of these sacs bursts, air is released into the pleural cavity, causing the lung to collapse. It also occurs in people with asthma, cystic fibrosis and pneumonia.

A spontaneous pneumothorax also can develop in people who don't have any obvious lung disease. It's most common in tall, thin men between the ages of 20 and 40 and smokers.

In most cases of pneumothorax, some air can move in and out through the tear in the lung or chest wall. If air can only move into the chest cavity, but not out, pressure builds up inside the pocket of trapped air. This is called a tension pneumothorax.

A tension pneumothorax can cause complete collapse of the nearby lung and can push the heart and major blood vessels to the other side of the chest. This is a life-threatening emergency. Tension pneumothorax most commonly occurs in people with penetrating chest injuries.


Symptoms of a collapsed lung include:


Your doctor may suspect you have a collapsed lung if you suddenly develop shortness of breath or chest pain, especially if you have had trauma to the chest. He or she will ask about your symptoms, your medical history and your smoking habits.

Your doctor will examine you, focusing on your general appearance, your vital signs (temperature, pulse, breath rate, blood pressure), and your lungs. The following signs can indicate that you have a collapsed lung:

A chest X-ray is the best way to confirm that you have a collapsed lung. The X-ray will show the collapsed lung as a dark area in the chest. A computed tomography (CT) scan may be needed to find a small collapsed area of a lung or for people with extensive lung disease.

Your doctor may check the oxygen level in your blood with a handheld device called a pulse oximeter or may draw blood from an artery in the wrist (an arterial blood gas test) to directly measure the levels of oxygen and carbon dioxide in your blood. He or she also may order an electrocardiogram (EKG), an electrical test of the heart.

Expected duration

Once the cause of a collapsed lung is treated, it usually will return to normal within 48 to 72 hours. Recovering from a collapsed lung may take up to several weeks.


Most cases of collapsed lung cannot be prevented. Quitting smoking can reduce your risk of developing the types of lung disease associated with this problem. Wearing your seat belt in the car and avoiding other activities that put you at risk of chest injuries can help you to avoid a collapsed lung caused by trauma.


A collapsed lung can be treated in several different ways. Your doctor will choose the right treatment based on several factors, including the size and location of the collapsed lung and your medical condition.

Treatment options include:

If you need to be admitted to the hospital for treatment, you will likely receive oxygen by nasal prongs or a mask for the first couple days.

You may be treated or observed for several days to make sure the collapsed lung re-expands. If you have had a serious chest injury or treatment does not expand your lung, your doctor will discuss the possibility of surgery to repair the lung and pleura. Sometimes damaged or scarred portions of lung are removed to allow the collapsed lung to heal. Traditional surgery requires the chest to be opened. But techniques using tiny cameras (thoracoscopy) are used more today because they result in less scarring and faster recovery times.

People with who keep developing a collapsed lung may need treatment to prevent it from happening again. Options include:

When to call a professional

Call your doctor if you have symptoms of a collapsed lung, especially if you have lung disease or have had a collapsed lung before. Even if your symptoms seem to improve, call your doctor. Some people with a collapsed lung notice that chest pain and shortness of breath improve in the first 24 hours, but the lung is still collapsed.


Once a collapsed lung has re-expanded and healed, there is usually no long-term effect on your health. However, up to 50% of people have a lung collapse again, especially within a few months of the first one. To decrease the risk of a second collapsed lung again:

Additional info

National Heart, Lung and Blood Institute (NHLBI)

American Lung Association

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.