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Pneumothorax (collapsed lung)

A pneumothorax is when air gets into the space between the outside of your lung and the inside of your chest wall, your ribcage. 

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What is a pneumothorax?

A pneumothorax is a collapsed lung.

A pneumothorax is when air gets into the space between the outside of your lung and the inside of your chest wall, your ribcage. A small pneumothorax may cause few or no symptoms. A large pneumothorax can squash the lung and cause it to collapse.

A pneumothorax can be small and get better with time. Or, it can be large and require urgent treatment. This depends on how much air gets trapped in the chest and if you have an existing lung condition.

Pneumothorax diagram of lungs

The air that builds up usually comes from a tear on the outside of the lung. But air can also come from outside your body if you have a chest injury.

If the tear is small, it will close as the lung collapses down so only a small amount of air can escape. If there is a larger hole, then the lung may collapse down completely.

If air continues to get into the pleural space as someone breathes, this can start to compress the other lung and heart. This is called a tension pneumothorax and can be life-threatening. Emergency treatment is needed to release the trapped air.

If someone becomes breathless with sudden chest pain, dial 999.

What causes a pneumothorax?

Primary spontaneous pneumothorax

This is when a pneumothorax develops in an otherwise healthy person, for no apparent reason. It’s the most common type of pneumothorax and happens most often in healthy young adults.

Primary spontaneous pneumothoraxes occur due to a small tear on the outer part of the lung. It’s not always clear why this happens but is probably due to an area of weakness when the lung is developing, like a small blister. Air escapes from the lung but gets trapped between the lung and the chest wall.

Secondary spontaneous pneumothorax

This is when a pneumothorax develops in someone who has an existing lung condition, usually chronic obstructive pulmonary disease (COPD). It’s more likely to occur if the condition weakens the edge of the lung, making it more likely to tear. Other lung conditions that may do this are:

Other causes of a pneumothorax

Pneumothorax can be caused by a chest injury, such as a car crash. It can also happen by accident during a medical procedure, when a needle is inserted into the chest. Acupuncture needles can cause a pneumothorax if they puncture the lining of the lung.

Pneumothorax can also occur after endobronchial valve placement to treat emphysema, or other surgery to the lung.

Who is at risk of a pneumothorax?

It’s more likely for men to have a pneumothorax than women. A primary spontaneous pneumothorax is more likely to happen in tall, thin people.

You’re more likely to have a pneumothorax if:

  • you have an existing lung condition
  • you smoke
  • you have had a pneumothorax in the past

If you’ve had a pneumothorax, stopping smoking will reduce the risk of it happening again.

What are the symptoms of a pneumothorax?

Symptoms include:

  • sudden, sharp stabbing pain on one side of the chest that gets worse when you breathe in
  • feeling breathless

You’ll usually be diagnosed by a chest X-ray. Sometimes you’ll also have a CT scan of your chest.

How is a pneumothorax treated?

The treatment of a pneumothorax depends on its size, and whether it’s expanding, as well as what has caused it. The aim is to relieve the pressure on your lung to allow it to re-expand.

If the pneumothorax is small, and the tear in your lung is small, the leak usually heals itself in a few days and the trapped air is gradually absorbed by your body. You can use over-the-counter painkillers if the pain is bad. You may have an X-ray after a week or so to check the pneumothorax has gone.

If a pneumothorax is causing breathlessness, you may be given oxygen.

The excess air may be removed by:

  • inserting a needle into the air-filled space and sucking the air out through a very thin tube using a syringe. This is called aspiration.
  • using a chest drain. This is a flexible plastic tube that’s inserted through the chest wall, after the area is numbed. The drain allows air out but not back in, so your lung can re-inflate. The tube is secured and stays in place until the air leak has resolved and the lung re-inflated. You will have to stay in hospital until it has resolved. On average, this is around 2 – 5 days, but it can be longer.

Pneumothorax diagram with chest tube

If a pneumothorax occurs more than once on the same side or an air leak persists despite aspiration or a chest drain, you might need to have a small operation. This will seal the weak areas on the edge of the lung where the air leaks are happening. This surgery may also involve a form of pleurodesis, where the lung is stuck to the inside of the chest wall, to make sure the lung can’t collapse again.

Flying and diving with a pneumothorax

Flying with a pneumothorax can be dangerous. This is because air in the pleural space in your chest will expand at the lower cabin pressure during the flight. This can compress the lung and can be dangerous. It’s important to wait until your doctor says it is safe before flying. This is usually a month after the pneumothorax happens and after a chest X-ray confirms it has been treated successfully.

You should not scuba dive if you have had a pneumothorax because of the risk of your lung collapsing again underwater. In some cases, surgical treatment can remove this risk. Ask your health care professional for more information.

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Download our pneumothorax information (517KB, PDF)

Last medically reviewed: October 2019. Due for review: September 2022

This information uses the best available medical evidence and was produced with the support of people living with lung conditions. Find out how we produce our information. If you’d like to see our references get in touch.