Interstitial Lung Disease

“Interstitial lung disease” (ILD) is a term for a group of conditions that cause inflammation and scarring in your lungs. ILD is the result of damage to the tissues between the small air sacs in your lungs (alveoli) and the blood vessels around them. This tissue is sometimes referred to as the intersitium or parenchyma.

The damage in ILD makes it hard for your lungs to get oxygen from the air to deliver to your tissues and to get carbon dioxide out of your body. This makes it hard to breathe. You might have a chronic cough or feel tired all the time. As damage gets worse, you can have life-threatening complications, like lung infections and respiratory failure.

Interstitial lung disease is different from conditions like COPD and asthma. These can have similar symptoms, but they affect your airways.

ILD is also called diffuse parenchymal lung disease (DPLD).

What are examples of interstitial lung disease?

Examples include:

• Idiopathic pulmonary fibrosis, the most common type of interstitial lung disease
• Diseases caused by exposures to harmful substances, like asbestosis and silicosis
• Chronic hypersensitivity pneumonitis, a severe type of allergic reaction to certain substances you inhale
• Radiation pneumonitis, inflammation from radiation therapy
• Nonspecific interstitial pneumonia, inflammation often caused by connective tissue disease

Symptoms of interstitial lung disease

Common symptoms of interstitial lung disease include:

• Shortness of breath that gets worse with physical activity or exertion
• Dry cough
• Fatigue
• Chest discomfort

Symptoms are usually mild at first, but get worse over months or years. You may have additional symptoms depending on the underlying cause of ILD.

Interstitial lung disease causes

Healthcare providers usually describe the causes of interstitial lung disease as known or unknown. A known cause is when ILD happens because of another health condition you have or something you were exposed to, like certain medications, radiation or harmful substances.

Known causes of interstitial lung disease include:

• Connective tissue disease, including rheumatoid arthritis (RA), lupus and scleroderma
• Granulomatous disease, like sarcoidosis
• Chronic inflammation from something you inhale, including molds, fungi, bacteria, and bits of bird feathers or droppings (poop)
• Medications or medical treatments, including amiodarone, nitrofurantoin, methotrexate and radiation therapy
• Toxic substances you could inhale, like asbestos, silica, tobacco and beryllium

An unknown cause is when you don’t have another health condition or exposures that caused ILD. This is called idiopathic interstitial pneumonia. There are many types. The most common is idiopathic pulmonary fibrosis.

Risk factors

You’re more likely to develop interstitial lung disease if you:

• Are over 70
• Smoke or used to smoke
• Have a history of certain illnesses or conditions, like hepatitis C, tuberculosis, pneumonia, COPD or connective tissue disease
• Work around substances that can irritate your lungs, like asbestos, silica, molds, fungi or bacteria
• Have had chest radiation

Complications

In severe cases of interstitial lung disease, you can have life-threatening complications, including:

• High blood pressure in your lungs
• Collapsed lung
• Lung infections
• Respiratory failure
• Lung cancer

How doctors diagnose interstitial lung disease

Healthcare providers diagnose interstitial lung disease by:

• Examining you
• Listening to your lungs for any unusual sounds
• Getting images of your lungs
• Testing your lung function

They might ask you about:

• Your medical history and any ongoing conditions
• Medications you’re taking or have taken in the past
• Whether anyone in your family has certain conditions or connective tissue diseases
• If your work or hobbies expose you to potential causes of ILD

Tests

Tests your provider may recommend include:

• Pulmonary function tests: These are breathing or exercise tests that check how well your lungs are working.
• Imaging tests: X-rays or high-resolution CT scans can provide pictures of your lungs.
• Blood tests: Your provider will test a sample of your blood for signs of known causes of ILD. Arterial blood gas tests can also check how well your lungs are working.
• Bronchoscopy: Your provider might use a thin tube (bronchoscope) to get a closer look at your airways.
• Biopsy: Your provider might take a small sample of tissue from your lungs. They’ll send the sample to a lab to help identify the type of ILD.

How is interstitial lung disease treated?

Treatment for ILD usually focuses on treating the underlying disease and improving your symptoms. This could include medications to reduce inflammation or slow down the disease. Your provider may also recommend treatments that can help improve your quality of life.

Treatments could include:

• Corticosteroids: Drugs like prednisone can help reduce inflammation.
• Anti-fibrotic drugs: These medications can slow down lung scarring. They include pirfenidone, nintedanib and nerandomilast.
• Cytotoxic or Immunosuppressive drugs: These medications can reduce inflammation and scarring often caused by autoimmune or connective tissue diseases. They include cyclophosphamide, azathioprine and mycophenolate mofetil.
• Biologic drugs: These medications are also used to treat autoimmune or connective tissue diseases, depending on the type. They help reduce inflammation. They include rituximab and tocilizumab.
• Treatment for GERD: Gastroesophageal reflux disease (GERD)can make ILD worse. Your provider may prescribe medications to keep stomach acid down.
• Pulmonary rehabilitation: Physical activity can help decrease how hard your lungs have to work on a regular basis, making breathing easier.
• Oxygen therapy: Your provider will prescribe oxygen if you don’t have enough getting to your blood or tissues.
• Lung transplant: Some people with severe cases of ILD are eligible for lung transplant.

When should I see my healthcare provider?

See your healthcare provider if you have symptoms that have gotten worse over time, an ongoing dry cough or shortness of breath that gets worse with exercise. The outlook for interstitial lung disease is best if treated as soon as possible.

What can I expect if I have interstitial lung disease?

Some forms of ILD aren’t reversible. Medications can help bring down inflammation depending on the type of ILD. And you might be able to slow down or prevent further damage.

How you and your healthcare provider treat ILD depends on the cause. For example:

• If you have an occupational exposure or hypersensitivity pneumonitis, you may need to take extra precautions if you work around certain substances. Your provider may recommend avoiding exposure to anything that can cause more inflammation.
• If you have another health condition causing inflammation, like an autoimmune or connective tissue disease, treating it might help prevent further damage.
• If the cause is unknown, your healthcare provider will treat your symptoms and recommend ways to lower your risk for further damage.

What’s the life expectancy for interstitial lung disease?

The life expectancy for interstitial lung disease depends on the cause and severity. Some people with mild ILD live their lives as usual without treatment or with minimal treatment. Your outlook (prognosis) is better if the damage isn’t getting worse.

For people with the most severe and rapidly worsening forms of interstitial lung disease, life expectancy may be as low as three to five years after diagnosis.

Can ILD be prevented?

Many causes of interstitial lung disease aren’t preventable. You can reduce your risk by managing underlying conditions and avoiding breathing in harmful substances.

• Avoid working around harmful substances, like asbestos, metal dusts or chemicals. Wear a respirator (a mask that filters particles from the air) if you must be around them.
• Avoid or wear a respirator when working around things that can cause chronic inflammation, like hay, grain, bird droppings or feathers, and heating and cooling systems.
• If you have a connective tissue disease or sarcoidosis, talk to your healthcare provider about ways to manage it to help prevent ILD.
• Don’t smoke or quit smoking.