Pulmonary fibrosis is a serious lung condition where the tissue around and between the tiny air sacs in your lungs becomes damaged, thickened, and scarred, making it increasingly difficult to breathe deeply and get enough oxygen to your body.
Understanding Pulmonary Fibrosis
When doctors talk about pulmonary fibrosis, they are describing a process where scar tissue builds up in the lungs. The word “pulmonary” refers to the lungs, while “fibrosis” means scarring—similar to the scars that might form on your skin after an injury or surgery. This scarring happens in a space called the interstitium, which is the tissue between the air sacs and blood vessels in your lungs.[1][3]
The condition is part of a larger family of more than 200 diseases known as interstitial lung diseases, or ILDs. What makes pulmonary fibrosis particularly challenging is that the scarred tissue becomes thick and stiff, preventing your lungs from expanding and contracting as they should. Over time, this stiffness makes it harder for oxygen to pass from your lungs into your bloodstream, leaving your body with less oxygen than it needs to function properly.[3][6]
How Common Is Pulmonary Fibrosis
Pulmonary fibrosis affects millions of people worldwide. At least 5 million people globally are living with this condition, though the exact number may be higher because many cases go undiagnosed or are mistaken for other lung problems.[7]
The condition is more common in certain groups of people. Most cases are diagnosed in middle-aged and older adults, typically those around 70 to 75 years old. It is rare in people under 50, and even more uncommon in children and infants. Men are more likely to develop pulmonary fibrosis than women. The disease also appears to run in families in some cases, with about 1 in 20 people with pulmonary fibrosis having another family member with the condition.[1][2][13]
What Causes Pulmonary Fibrosis
The exact cause of pulmonary fibrosis remains unclear in many cases, which is why the term “idiopathic” is used so often. However, researchers believe that the condition develops when the lungs do not heal properly after damage or inflammation. Instead of repairing themselves normally, the lungs form scar tissue.[2][5]
When a cause can be identified, it usually falls into one of several categories. Environmental exposures are a common trigger. Breathing in harmful substances over long periods—such as asbestos, silica dust, metal dust, or coal dust—can damage the lungs and lead to scarring. People who work in industries like mining, construction, or manufacturing may be at higher risk due to these exposures.[2][7]
Certain medications and medical treatments can also cause pulmonary fibrosis. Drugs such as amiodarone (used for heart rhythm problems), nitrofurantoin (an antibiotic), methotrexate (used for autoimmune diseases), and chemotherapy drugs like bleomycin have been linked to lung scarring. Radiation therapy to the chest, often used to treat cancer, can also damage lung tissue.[2][7]
Autoimmune and connective tissue diseases can lead to pulmonary fibrosis as well. Conditions such as rheumatoid arthritis, lupus, and scleroderma cause the body’s immune system to mistakenly attack healthy tissues, including the lungs. This ongoing attack can result in inflammation and scarring.[2]
Infections, particularly viral infections, and certain inflammatory conditions like sarcoidosis have also been associated with the development of pulmonary fibrosis. In some cases, the condition may result from hypersensitivity pneumonitis, which is an allergic reaction to inhaled dusts containing mold, bacteria, or bird feathers and droppings.[2][7]
Some researchers believe that in idiopathic pulmonary fibrosis, lung cells age too quickly. These aging cells are unable to repair damage normally and instead cause scar tissue to form. Factors that cause lung cells to age faster—such as genetics, environmental exposures, and other risk factors—can increase the likelihood of developing pulmonary fibrosis.[6]
Who Is at Risk
While pulmonary fibrosis can develop in anyone, certain factors increase the likelihood of developing the condition. Age is one of the most significant risk factors. People aged 65 and older are much more likely to be diagnosed with pulmonary fibrosis than younger individuals.[2][8]
Men are at higher risk than women. Smoking or having a history of smoking greatly increases the chances of developing lung scarring. Even if someone has quit smoking, the damage caused by years of tobacco use can still contribute to the development of pulmonary fibrosis.[2][8]
People with a family history of pulmonary fibrosis are also at increased risk. Genetic factors appear to play a role in some cases, with certain mutations in genes that encode proteins important for lung health being identified in families with a history of the disease. For example, mutations in surfactant protein C and genes related to telomerase have been found in some patients.[2][7]
Occupational exposures are another major risk factor. People who work in jobs where they regularly breathe in dust, gases, or chemical fumes—such as farmers, construction workers, hairdressers, or metal workers—have a higher risk. Exposure to substances like wood dust, metal particles, silica, coal, and aerosol sprays can all damage the lungs over time.[8]
Gastroesophageal reflux disease, commonly known as GERD, is also associated with pulmonary fibrosis. When stomach acid repeatedly flows back into the esophagus, tiny amounts of stomach content can sometimes be inhaled into the lungs, potentially causing damage.[8]
Recognizing the Symptoms
The symptoms of pulmonary fibrosis tend to develop gradually and worsen over time. Many people initially ignore their symptoms, blaming them on aging, being out of shape, or having a cold that just won’t go away. However, these symptoms are not normal and should not be dismissed.[1][13]
Shortness of breath is the most common symptom. At first, you might only notice it during physical activity or exercise. You might feel winded after climbing stairs or walking quickly. As the disease progresses, breathlessness can occur even during light activities like getting dressed, talking, or eating. Eventually, some people feel short of breath even when resting.[1][2]
A persistent dry cough is another hallmark symptom. This cough does not produce mucus and does not go away with typical cough remedies. It can be chronic and frustrating, sometimes triggering fits of coughing that disrupt sleep and daily activities.[1][2]
Extreme tiredness and fatigue are common. People with pulmonary fibrosis often feel exhausted even after minimal effort. This fatigue is partly due to the body not getting enough oxygen. Weight loss that is not intentional can also occur, along with loss of appetite.[1][2]
Aching muscles and joints may develop, making it uncomfortable to move or stay active. Some people also experience a condition called clubbing, where the tips of the fingers or toes become widened and rounded. The nails may appear curved and bulging. Clubbing is a visible sign that the body is not getting enough oxygen over a long period.[1][2]
In some cases, the skin around the lips, eyes, or nails may take on a bluish, gray, or white tint, a condition known as cyanosis. This occurs when oxygen levels in the blood are very low.[2]
Can Pulmonary Fibrosis Be Prevented
Not all cases of pulmonary fibrosis can be prevented, especially when the cause is unknown. However, there are steps people can take to reduce their risk or slow the progression of the disease if they are already at risk.[8]
If you smoke, quitting is one of the most important things you can do for your lung health. Smoking damages the lungs and increases the risk of many lung diseases, including pulmonary fibrosis. Even if you have already been diagnosed, stopping smoking can help slow the disease’s progression.[2]
Avoiding exposure to harmful substances is also crucial. If you work in an environment where you are exposed to dust, fumes, or chemicals, follow occupational safety guidelines carefully. Use proper protective equipment such as masks, respirators, and ventilation systems. If possible, limit the amount of time you spend in environments with poor air quality.[8]
Managing other health conditions can also help. If you have GERD, treating it effectively may reduce the risk of stomach acid damaging your lungs. If you have an autoimmune disease, working closely with your doctor to control inflammation may help protect your lungs.[2]
Staying up to date with vaccinations, particularly for flu and pneumonia, can help prevent lung infections that might worsen pulmonary fibrosis. Eating a balanced diet, staying physically active within your limits, and maintaining a healthy weight can all support overall lung health.[8]
How the Lungs Are Affected
To understand what happens in pulmonary fibrosis, it helps to know how healthy lungs work. Your lungs are made up of a network of tubes that carry air into small sacs called alveoli. These sacs are surrounded by tiny blood vessels. Oxygen from the air you breathe moves from the alveoli into the blood, while carbon dioxide moves from the blood into the alveoli to be exhaled. The space between the alveoli and the blood vessels, known as the interstitium, contains cells that help the lungs function properly.[6]
In pulmonary fibrosis, the interstitium becomes scarred and thickened. This makes the lungs stiff and less stretchy. Stiff lungs cannot expand and contract easily, so it becomes harder to take deep breaths. The thickened tissue also acts as a barrier, making it more difficult for oxygen to pass from the alveoli into the bloodstream. As a result, less oxygen is available for the body to use, leading to symptoms like shortness of breath and fatigue.[1][6]
The scarring process in pulmonary fibrosis can occur through two main mechanisms. In some types of interstitial lung disease, inflammation is the starting point. When something irritates or injures the lungs—such as an autoimmune attack or inhaled dust—the body responds with inflammation. If this inflammation is prolonged or severe, it can lead to scarring.[5][6]
In other cases, particularly idiopathic pulmonary fibrosis, the problem may be that lung cells age too quickly. Normally, when lung cells are damaged, they are replaced by new, healthy cells. But in pulmonary fibrosis, aging cells cannot repair damage properly. Instead of creating new healthy tissue, they produce scar tissue. This faulty repair process is thought to be driven by genetic factors, environmental exposures, and other risk factors that cause cells to age prematurely.[6]
As the disease progresses, the scarred lung tissues have a hard time getting oxygen to the rest of the body. This forces the heart to work harder to pump blood through the lungs. Over time, this extra strain can lead to complications such as pulmonary hypertension (high blood pressure in the lungs), heart failure, and respiratory failure. The scarred, fragile lung tissue is also more prone to collapse and infections.[2][7]
