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Pulmonary fibrosis

What is pulmonary fibrosis?

On this page we explain what pulmonary fibrosis means and what an interstitial lung disease (ILD) is. We also discuss the outlook of pulmonary fibrosis and explain how pulmonary fibrosis can affect your breathing. 

On this page:

What is pulmonary fibrosis?

Pulmonary fibrosis is the buildup of scar tissue in your lungs. It makes breathing increasingly difficult.     

Some types of pulmonary fibrosis have an identifiable cause. But for many types, a definite cause cannot be found. 

Although we do not always know what causes pulmonary fibrosis, we do know it is not a form of cancer or cystic fibrosis, and it’s not contagious. Read more about the causes of pulmonary fibrosis.

  • pulmonary: it affects your lungs
  • fibrosis: the name for a build-up of scar tissue, which makes your lungs stiff. You might hear ‘fibrosis’ used to mean hardening

What are interstitial lung diseases?

Interstitial lung disease (ILD) is the name for a group of lung conditions that damage the lung tissue. There are more than 200 different ILDs.

Interstitial lung diseases cause scarring in your lungs (pulmonary fibrosis), inflammation in your lungs or a mix of both. Some mostly cause scarring. Some mostly cause inflammation. Often there is a combination of scarring and inflammation. It’s important to know what the major cause of your symptoms is to help your health care team decide the best treatment for you. 

Interstitial: affects your ‘interstitium’, the network of tissue that supports the air sacs in your lungs

Our information covers the ILDs seen most often:

What’s the outlook?

Most forms of pulmonary fibrosis tend to get worse over time. The likelihood of this happening and how quickly it happens varies with the type of pulmonary fibrosis, but also from person to person. This makes it difficult to predict exactly how fast symptoms may progress and change. The aim of treatment is to slow down this rate of change. The chance of success depends on the exact diagnosis and how well you can tolerate treatment. You will be monitored and have regular tests of your lung function to look for changes.

In some people, pulmonary fibrosis progresses very quickly, while for others their condition remains stable for many years. Some conditions progress at a steady rate. In others, apparently stable conditions can change suddenly. This sudden worsening of symptoms is called an exacerbation. 

There are no defined stages in pulmonary fibrosis, but doctors may talk about mild, moderate, severe, or end-stage fibrosis.

Questions about diagnosis, treatment and outlook?

The treatment and outlook for different types of pulmonary fibrosis varies considerably. If you’re not sure about your diagnosis, check with your doctor or nurse for the exact name of your lung condition. 

If you are unsure what to ask your health care professional when you have, or could have, pulmonary fibrosis, try reading this helpful list. It suggests questions to ask about diagnosis, treatments and much more.

How does pulmonary fibrosis affect your breathing?

All kinds of pulmonary fibrosis cause scarring in your lungs that make breathing more difficult. Scarring makes your lungs stiffer and less elastic so they’re less able to move and take oxygen from the air you breathe.  

How do you breathe?

Each time you breathe in, you draw air into your nose or mouth, down through your throat and into your windpipe. Your windpipe splits into two smaller air tubes called bronchi, which go to your lungs. The air passes down the bronchi, which divide again and again, into thousands of smaller airways called bronchioles. 

The bronchioles have many small air sacs, called alveoli. Inside the air sacs, oxygen moves across paper-thin walls to the capillaries - tiny blood vessels - and into your blood. The air sacs also pick up the waste gas, carbon dioxide from your blood, ready for you to breathe it out.  

Diagram of the lungs, airways, bronchioles, and air sacs

How does pulmonary fibrosis change your breathing?

If you have pulmonary fibrosis, scarring affects the air sacs in your lungs. The air sacs are supported by the ‘interstitium’, a network of supporting tissue. Scarring happens in the gaps between and around the air sacs and limits the amount of oxygen that gets into the blood.

Air sacs of the lungs in pulmonary fibrosis

As scarring increases, your lungs are less able to expand to allow you to take deep breaths and the level of oxygen in your blood can start to drop. Breathing may feel like harder work and you can feel breathless from everyday activities like walking.   

Need help managing breathlessness? Take a look at our online information – it’s got different techniques and positions you can try when you’re feeling short of breath.

Next: Causes of pulmonary fibrosis

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Last medically reviewed: June 2022. Due for review: June 2025

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.