What Are Interstitial Lung Diseases?

Medically Reviewed By Luke Davis, MD
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Interstitial lung disease is a medical term describing a large group of lung diseases involving scarring of the lungs. The inflammation and scarring may make breathing more difficult.  There is an ever-growing list of potential causes; sometimes, the cause is never known.

Treatment of interstitial lung diseases (ILDs) may include lifestyle changes, medication, supplemental oxygen, and pulmonary rehabilitation. Sometimes, a lung transplant is necessary.  

This article discusses ILD causes and symptoms. It also discusses the diagnosis, treatment plan, and potential complications. Lastly, learn about the potential outlook for someone with an ILD. 

Interstitial lung diseases explained

blue lungs concept
Yaroslav Danylchenko/Stocksy United

Interstitial lung disease (ILD) is not a disease on its own but is an umbrella term describing over 200 diseases that cause lung scarring, or fibrosis. About 3 out of every 10,000 people receive an interstitial lung disease diagnosis each year, according to the National Heart, Lung, and Blood Institute (NHLBI). 

Your lungs are sponge-like sacs full of air passageways and tiny blood vessels. This allows for the gas exchange of carbon dioxide and oxygen. Healthy lungs are soft and flexible. They inflate easily when you inhale and deflate when you exhale. 

Fibrosis is the medical term for scarring. ILDs are a group of diseases that cause inflammation and scarring in the lungs, making them stiff and difficult to inflate. It also makes the gas exchange of carbon dioxide and oxygen more challenging. When this happens, your body has less oxygen and builds up harmful carbon dioxide. 

Learn more about how alveoli exchange gas here.

Causes of interstitial lung disease

Lung damage causes interstitial lung diseases (ILDs). It may come from:

  • inhaled environmental exposures
  • genetics
  • other medical conditions
  • unknown factors

It can be a combination of these factors as well. For example, a person’s genetic background may predispose them to ILD from inhaling dust at work.

Your body then attempts to repair the damage, but when the damage leads to ILD, the typical repair processes stop working correctly. Instead, scar tissue forms in the lungs. Scar tissue is thick and stiff, making air inflation difficult. You cannot reverse these changes. 

Anyone, including children, can get these lung diseases, says the American Lung Association (ALA). Certain factors increase the chance of developing an ILD. Doctors classify ILDs by the identifiable cause. Below is a summary of specific diseases.

Idiopathic pulmonary fibrosis

The largest category of ILDs is when scarring develops in the lungs for unknown reasons. The NHLBI defines this as idiopathic pulmonary fibrosis. It is more common in people in their 60s and 70s.

Idiopathic pulmonary fibrosis progresses differently for everyone. Sometimes scarring develops quickly and progresses rapidly. According to the American Thoracic Society, idiopathic pulmonary fibrosis shortens life expectancy.  

People with idiopathic pulmonary fibrosis may experience times when their symptoms suddenly become much more severe. 

Learn about idiopathic pulmonary fibrosis here.


You are more likely to develop an ILD if you have a close relative with one. You may carry specific gene variations or mutations that make your lungs more susceptible to developing scar tissue. 


Researchers know that smoking can cause ILD. It can also make the disease progress faster. Smoking is a common habit among people who develop ILD.

Exposure to hazardous materials

Long-term exposure to environmental or occupational materials can have damaging effects on the lungs.

Examples of hazardous materials include:

  • mineral dust:
    • silica
    • asbestos
    • coal mine dust
    • beryllium
    • hard metal
  • organic dust:
    • mold spores
    • air particles from bird droppings and feathers

Specific ILDs include:

  • Silicosis: Silica is a common mineral found in rocks and sand. It causes permanent lung damage over time. Occupations with potentially high silica exposure include stone countertop fabrication and ceramics manufacturing.
  • Asbestosis: Asbestos is a naturally occurring mineral found in insulation materials and fire retardants. It can cause lung scarring if inhaled in large amounts over long periods. 
  • Hypersensitivity pneumonitis: This is lung inflammation after exposure to something that causes an allergic reaction. It is rare, but sometimes hypersensitivity pneumonitis causes permanent lung scarring.

Health conditions

Certain health conditions increase the chance of developing an ILD. Conditions include:

Medical treatments or medication

Certain medical treatments like radiation, chemotherapy, and over 350 medications increase a person’s chance of lung damage, including ILD. According to the 2018 systematic review, DIILD accounted for 3–5% of prevalent ILD cases.

Symptoms of interstitial lung disease 

The most common symptom of ILD is a gradual onset of shortness of breath

A person experiencing early symptoms may notice they feel out of breath more quickly. They may sense the need to stop and catch their breath doing typical daily activities like laundry. 

Other early-onset symptoms may include:

It is important to see a medical professional as soon as you notice symptoms to prevent complications.

People with advanced ILD may have finger clubbing. The fingertips may enlarge and the fingernails turn down at the end. They may also have a bluish tint in their fingernails and toenails and around their lips and mouth. 

How do doctors diagnose interstitial lung disease?

A healthcare professional will first want to discuss your symptoms and review your medical history, including current medications, vitamins, and supplements. They will also inquire about your potential exposures, including those at home, work, or school. Knowing this information is key to the diagnosis.

During the exam, they will check your vital signs, including your oxygen saturation level, and listen to your lungs with a stethoscope. Lung fibrosis can cause high-pitched crackles — sounds that come from the small airways (bronchioles and smaller) snapping open as you breathe in.

They may order diagnostic tests and refer you to a pulmonologist, a physician who specializes in lung conditions.

In general, tests for pulmonary fibrosis may include: 

  • lung function tests, to evaluate lung capacity and the severity of the disease
  • blood tests, to check organ function and any underlying autoimmune causes
  • imaging tests, to look for scarring:
  • lung biopsy, to verify the diagnosis

Your and your doctor will discuss the test results and create a treatment plan.

What is the treatment for interstitial lung disease?

The goal of treatment is to prevent further damage and relieve your symptoms as much as possible. Your treatment depends on the type and stage of ILD. 

Lifestyle changes

If you smoke, it is very important to stop smoking, as it increases lung damage. Talk with your healthcare professional about how you can stop smoking.

If your ILD stems from exposure to environmental or occupational hazardous material, you need to avoid further exposure. If you develop ILD as an occupational hazard, you may be eligible for compensation through the United States Department of Labor.


Several types of medications can make it easier to breathe. Depending on the specific ILD and severity, medications may include: 

  • Bronchodilators: These relax the muscles in your airways, helping your airways open wider. Usually, these medicines come in a device called an inhaler. 
  • Corticosteroids: These may help decrease inflammation in your lungs. These are taken in pill form or through an inhaler. 
  • Antifibrotics: These pills may slow down lung damage by blocking growth factors that cause scarring in the lungs.

Oxygen therapy

Oxygen therapy is a treatment that delivers oxygen through a tube resting under your nose, a face mask, or a tube placed in your trachea. Oxygen therapy will increase your body’s oxygen levels.

Read about oxygen levels here.

Pulmonary rehabilitation

Pulmonary rehabilitation is for people with certain lung conditions or after a lung transplant. It is a program that includes:

  • exercise training
  • health education
  • breathing techniques
  • emotional support

Learning these skills can improve your breathing, which can relieve symptoms and allow you to be more active. In turn, this can increase quality of life. 

Lung transplant

People with severe ILD may receive recommendations for a lung transplant. The surgery involves removing the unhealthy lung and replacing it with a healthy one.

What are the complications of interstitial lung disease?

Left untreated, ILDs can develop into a life threatening condition, such as respiratory failure and heart failure. 

It is important to seek medical care at the first signs of ILD.

Also, if you have risk factors for ILD, discuss them with your doctor and explore ways you can reduce your risk.

Can you prevent interstitial lung disease?

The most common type of ILD is idiopathic pulmonary fibrosis, which has no known cause. This makes it difficult to prevent. However, you can help reduce your chance of developing an ILD by avoiding occupational and environmental exposure to known toxins, such as silica and mold.  

If you smoke, try to stop smoking to prevent further lung damage.

If you have an underlying medical condition, following your treatment plan may help reduce your chance of a related ILD.

What is the outlook?

Your outlook depends on the type of ILD, how early treatment starts, and your overall health. 

In general, lung damage from an ILD is not curable and worsens with time. However, medical treatment may slow further damage to the lungs, relieve symptoms, and delay complications.

To live well and maintain a good quality of life, the ALA recommends you:

  • eat healthy
  • stay physically active
  • reduce stress
  • stay inside on high pollution days and avoid other exposures
  • follow your treatment plan to manage symptoms
  • join a support group, such as the ALA Better Breathers Club

Frequently asked questions

Luke Davis, M.D. reviewed the following questions.

How serious is interstitial lung disease?

ILD is a serious condition that affects lung function. Without treatment, scarring continues and this can lead to life threatening conditions, such as heart or respiratory failure

What is the most common cause of interstitial lung disease?

Many times, the cause of ILD is not known. Inhaling toxins, including cigarette smoke, and occupational dusts appear to be major causes.   


Interstitial lung disease (ILD) is an umbrella term medical professionals use to describe a group of lung conditions that cause scarring in the lungs. 

This scarring in the lungs makes breathing difficult and people with ILD may find themselves feeling short of breath doing normal activities. 

If you have unexplained breathing or related symptoms, contact a medical professional.  

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Medical Reviewer: Luke Davis, MD
Last Review Date: 2022 Aug 24
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