What is Pulmonary Fibrosis?


What does "pulmonary fibrosis" mean?

The word “pulmonary” means lung and the word “fibrosis” means scar tissue— similar to scars that form on the skin from an old injury or surgery. Pulmonary fibrosis (PF) is a process that causes lung scarring, in which fibrotic tissue blocks the movement of oxygen from inside the tiny air sacs in the lungs into the bloodstream. Low oxygen levels (and the stiff scar tissue itself) can cause people who have pulmonary fibrosis to feel short of breath, particularly when walking and exercising.

Interstitial lung disease and pulmonary fibrosis

Pulmonary fibrosis isn’t just one disease. It is a family of more than 200 different lung diseases that all look very much alike. The PF family of lung diseases is part of an even larger group of diseases called interstitial lung diseases (also known as ILD), which includes all of the diseases that have inflammation and/or lung scarring. In ILDs, it is the walls of the air sacs of the lung, and the tissue and space around these air sacs, where the injury and damage occur. Some interstitial lung diseases don’t include lung scarring. When an interstitial lung disease does include scar tissue in the lung, we call it pulmonary fibrosis.


Pulmonary fibrosis and interstitial lung disease statistics

No one is certain how many people are affected by PF. One recent study estimated that idiopathic pulmonary fibrosis (or IPF, which is just one of more than 200 types of PF) affects 1 out of 200 adults over the age of 70 in the United States. There are over 250,000 Americans living with PF today. Approximately 50,000 new cases are diagnosed each year and as many as 40,000 Americans die from IPF each year.

Causes of PF

When a person is diagnosed with pulmonary fibrosis (PF), sometimes there is a clear association with another illness, or the lung scarring (fibrosis) is the result of a side effect from a medication, radiation treatments to the chest, or an environmental or occupational exposure known to cause PF. Pulmonary fibrosis that is associated with another disease, such as scleroderma or rheumatoid arthritis, would be referred to as pulmonary fibrosis secondary to scleroderma or secondary to rheumatoid arthritis. When the cause of the disease is not known, the term “idiopathic” is used. There are multiple forms of ILD that are idiopathic, but idiopathic pulmonary fibrosis (IPF) is the most common of the idiopathic types of ILD. There are also some patients who have a form of PF that runs in families, which affects from 3-20% of people who are diagnosed with PF.

Progression of pulmonary fibrosis

The clinical course of PF is highly variable and often difficult to predict. It is important for a PF patient to have an accurate diagnosis because their treatments, disease management and prognosis may vary depending on the type of pulmonary fibrosis they have. Even among patients with similar diagnoses, some may experience rapid progression of their disease while others can remain at the same level of functioning for a longer time. Many types of PF can be complicated by episodes of sudden declines in lung function and oxygen levels, known as acute exacerbation, from which most patients do not fully recover. These events can sometimes result in other problems such as heart failure, high blood pressure in the lungs (pulmonary hypertension) and other co-morbidities (diseases).

As the lung scarring in PF progresses, breathing becomes more difficult with increased demand for higher flows of oxygen. This demand for more oxygen may cause increased breathlessness, particularly with activity, and anxiety. Patients may also experience an increase in other associated symptoms as their disease progresses such as cough, fatigue, and deconditioning.

What researchers are doing to help

The Pulmonary Fibrosis Foundation is leading the fight by funding promising research and we need your help. 

One of our key research programs is the PFF Community Registry. We invite eligible participants to join by completing a series of simple surveys. Your survey responses will be used by researchers to better understand how PF and ILD progress over time, respond to treatments, and how the diseases affect individuals. The more individuals who join and provide responses, the closer we come to a cure.

Eligible participants include:

  • Patients living with PF and ILD
  • Lung transplant recipients who have had PF or ILD
  • Caregivers and biological family members of patients with PF or ILD, including those who have passed away

Enrolling in the PFF Community Registry is entirely online. All you need is internet access. Learn more about this groundbreaking program by visiting the PFF Community Registry homepage

map showing people all over the United States

Educational Materials

Find reliable information and trusted resources that can help you learn about pulmonary fibrosis and live better with PF.


  • Pulmonary Fibrosis Quick Facts

    This one-page document provides quick facts about pulmonary fibrosis, including symptoms, causes, treatment options, and more.
    View Full Details
  • Pulmonary Fibrosis Information Guide

    Our comprehensive guide provides reliable information about pulmonary fibrosis, the diagnostic process, treatment options, and more.
    View Full Details

PFF Help Center

For those living with pulmonary fibrosis, obtaining the most accurate and current information can be a frustrating and challenging task. Let us help you find your answers.


Find a doctor or a PF support group

The Pulmonary Fibrosis Foundation is pleased to offer this search tool to help you find expert pulmonologists (lung doctors) and support groups in your area. Each medical center listed is an official PFF Care Center Network site, providing expert care for people living with pulmonary fibrosis. Further, more than 150 PF support groups are welcoming new members, with many of them meeting virtually. You may also join one of the PFF's four official support groups on Zoom.

To quickly find resources in your area, use the search feature below by entering your zip code. Use the checkboxes to filter results.

Please email help@pulmonaryfibrosis.org or call 844.TalkPFF with any further questions.