Interstitial Lung Disease: What It Is, What Causes the Scarring, and What Treatment Can Actually Do
Updated: 3 days ago
Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: October 2026
Quick Answer: What is interstitial lung disease?
Interstitial lung disease (ILD) is a large group of conditions in which tissue around the lungs' air sacs becomes inflamed and scarred, stiffening the lungs. The main symptoms are shortness of breath and a persistent dry cough. Scarring is generally not reversible, but some medicines can slow progression, and early diagnosis by a pulmonologist is important.
What the research says
Nintedanib slows the loss of lung function in idiopathic pulmonary fibrosis. In two trials with 1,066 patients, forced vital capacity fell by 114.7 ml per year with nintedanib versus 239.9 ml with placebo in the first trial (Richeldi et al., N Engl J Med, 2014) [2].
Pirfenidone also slows disease progression. In a trial of 555 patients, pirfenidone reduced by 47.9% the proportion of patients who had a major drop in lung capacity or died over 52 weeks, compared with placebo (King et al., N Engl J Med, 2014) [3].
What Is Interstitial Lung Disease?
Interstitial lung disease (pronounced in-tur-STISH-ul), also called ILD, is not one single disease. It describes a large group of conditions that share one common feature: inflammation and progressive scarring of the lung tissue that sits around and between the tiny air sacs.
To picture how this works, it helps to know how your lungs are built. The main airways, called bronchi, branch into smaller and smaller passageways. The smallest airways, called bronchioles, lead to tiny air sacs called alveoli, where oxygen passes into the bloodstream. ILD affects the tissue in and around these air sacs.
As the tissue scars, it thickens and stiffens. The lungs lose their stretchiness, so it becomes harder for them to expand and fill with air. It also becomes harder for oxygen to move from the air sacs into the blood.
At some point, the scarring makes it harder to breathe and to get enough oxygen into the bloodstream. Many people with ILD are short of breath with activity and develop a bothersome dry cough.
The disease may get worse slowly or rapidly, at a pace that often can't be predicted. Once lung scarring occurs, it generally isn't reversible. That's why treatment focuses on keeping more scarring from occurring, managing symptoms, and making quality of life better. Some medicines may slow the damage, but many people never fully use their lungs again. Lung transplant is an option for some people with ILD.
Symptoms: Shortness of Breath and a Dry Cough
The main symptoms of interstitial lung disease are:
Shortness of breath at rest, or shortness of breath that worsens with physical activity.
A dry cough.
When to see a doctor
By the time symptoms appear in certain types of interstitial lung disease, lasting lung damage has already occurred. That's why it's important to see a healthcare professional at the first sign of breathing problems.
This urgency matters even more because many conditions other than ILD can affect your lungs. Getting an early and correct diagnosis is important for proper treatment — a mislabeled cough and breathlessness can mean a different disease entirely.
What Causes Interstitial Lung Disease?
ILD seems to occur when an injury to the lungs causes a healing response that isn't proper. Ordinarily, your body creates just the right amount of tissue to repair damage. But in ILD, the repair process doesn't work properly. Tissue in and around the air sacs becomes inflamed, scarred, and thickened.
There are many types of interstitial lung disease. They're generally grouped by known or unknown causes:
Cause Group | What Happens | Examples |
Work or environment | Long-term exposure to toxins and pollutants damages the lungs | Asbestosis, coal miner's lung, silicosis, hypersensitivity pneumonitis |
Underlying systemic condition | A disease elsewhere in the body drives inflammation in the lungs | Rheumatoid arthritis, scleroderma, sarcoidosis |
Medications or radiation | Drug damage or chest radiation scars lung tissue | Certain chemotherapy drugs, amiodarone, some antibiotics, methotrexate |
No known cause | The cause is never found — labeled "idiopathic" | Idiopathic pulmonary fibrosis (IPF), cryptogenic organizing pneumonia (COP) |
Some interstitial lung diseases can also be related to smoking.
Work and environment
Long-term exposure to some toxins and pollutants can damage your lungs.
Pneumoconiosis (pronounced noo-moe-koh-nee-O-sis) refers to a type of ILD caused by breathing in certain kinds of dust from work or another environment over a long time. Diseases in this group cause lung scarring and injury over time, leading to shortness of breath and poor ability to take in oxygen — symptoms that can't be reversed. These diseases are often named after the exposure type or work role itself. They include coal miner's lung (breathing in coal dust), asbestosis (breathing in asbestos particles), and silicosis (breathing in silica dust).
Hypersensitivity pneumonitis is lung inflammation caused by breathing in airborne irritants, often involving the proteins of living things. The most common of these airborne irritants are bird protein, mold, or bacteria. Conditions of this type are also often named after the source of exposure — for example, pigeon-breeder's or bird-lover's disease (bird protein) and farmer's lung (moldy hay). People with this type of lung inflammation can get better by staying away from the irritant. But the inflammation can also get worse and lead to more-lasting damage if people continue to breathe in the irritant.
Underlying systemic conditions
Certain diseases or conditions may lead to interstitial lung disease.
Connective tissue diseases include autoimmune diseases such as rheumatoid arthritis, scleroderma, and mixed connective tissue disease. These diseases result in an immune response that isn't proper and may cause tissue inflammation and scarring in the body, including in the lungs.
Sarcoidosis is a disease that includes the growth of tiny collections of inflammatory cells called granulomas in any part of the body — most commonly the lungs and lymph nodes. Other commonly affected organs include the eyes, skin, heart, spleen, and liver.
Medications and radiation
Certain types of medicines can cause interstitial lung disease in some people. Whether this damage is reversible may depend on the type and length of exposure.
Medicines more commonly associated with ILD include:
Medicine Category | Examples |
Chemotherapy drugs | Bleomycin, gemcitabine, and immune checkpoint inhibitors — drugs designed to kill cancer cells that can damage lung tissue |
Heart medicines | Amiodarone, used to treat irregular heartbeats, may harm lung tissue |
Some antibiotics | Nitrofurantoin and daptomycin can cause lung damage |
Anti-inflammatory drugs | Methotrexate or sulfasalazine can damage the lungs |
Radiation directed at the chest during treatment for certain cancers — breast and lung cancers, for example — may lead to injury or long-term scarring in some people. How severe the damage is may depend on how much of the lung was exposed, the total amount of radiation given, whether chemotherapy was also used, and whether there is underlying lung disease.
When no cause is found
The list of substances and conditions that can lead to interstitial lung disease is long. Even so, in some people the cause is never found. Conditions without a known cause are grouped together under the label of idiopathic interstitial pneumonias.
Idiopathic pulmonary fibrosis, also called IPF, is a typically progressive lung disease that occurs when lung tissue becomes damaged and scarred — what's known as fibrosis. "Idiopathic" means the cause isn't known. IPF can be seen on imaging and biopsy. This thickened, stiff tissue makes it harder for the lungs to work properly. The most common type of ILD, IPF often gets worse and can't be reversed.
Cryptogenic organizing pneumonia, also called COP, is a rare lung condition in which the small airways (bronchioles) and tiny air-exchange sacs (alveoli) get inflamed, making it hard to breathe. Imaging tests show pneumonia, but COP is not an infection, and the cause is not known. Scarring or fibrosis is rare, but it can happen in some patients if the condition comes back.
Nonspecific interstitial pneumonia causes cells to be inflamed or scar tissue to build up in the spaces between the air sacs in the lungs. It's more likely to happen in people with connective tissue diseases, but it can also be linked to other conditions.
Who Is Most at Risk?
Factors that may make you more likely to get interstitial lung disease include:
Risk Factor | Why It Raises Risk |
Age | ILD is much more likely to affect adults, although babies and children sometimes get the disease |
Toxin exposure at work or in the environment | Working in mining, farming, or construction, or any exposure to lung-damaging pollutants, raises your risk |
Smoking | Some forms of ILD are more likely in people with a history of smoking; active smoking may make the condition worse, especially with emphysema |
Radiation and chemotherapy | Radiation treatments to the chest or certain chemotherapy drugs raise your risk of lung disease |
Connective tissue disease | Autoimmune diseases can raise your risk of ILD |
What Complications Can Develop?
Interstitial lung disease can lead to a series of life-threatening complications:
High blood pressure in the lungs, also known as pulmonary hypertension. Unlike systemic high blood pressure, this condition affects only the arteries in the lungs. Scar tissue or low oxygen levels restrict the smallest blood vessels, limiting blood flow in the lungs. This raises pressure within the pulmonary arteries and can worsen oxygen exchange, lowering oxygen levels in the blood. Pulmonary hypertension is a serious illness that may get worse over time, causing the right side of the heart to fail.
Right-sided heart failure, also known as cor pulmonale. This serious condition occurs when the heart's lower right chamber, the right ventricle, must pump harder than usual to move blood through blocked pulmonary arteries. Eventually the right ventricle fails from the extra strain. This is often due to pulmonary hypertension.
Respiratory failure. In the end stage of chronic ILD, respiratory failure occurs when severely low blood oxygen levels, along with rising pressures in the pulmonary arteries and the right ventricle, cause the heart to fail.
Can Interstitial Lung Disease Be Prevented?
To prevent interstitial lung disease, avoid exposure to toxins at work, such as asbestos, coal dust, and silica dust. Also, avoid exposure to toxins in the environment, such as bird protein, mold, and bacteria. If you must be around these toxins, protect yourself by wearing a respirator.
Other ways to prevent ILD include not smoking and avoiding secondhand smoke. If you have an autoimmune disease or are taking medicines that raise your risk of getting ILD, talk with your healthcare professional about steps you can take to prevent it.
Vaccination also plays a role. Respiratory infections can make symptoms of ILD worse, so get the pneumonia vaccine and a flu shot each year. Also, ask your healthcare professional about getting vaccinated for pertussis, COVID-19, and respiratory syncytial virus (RSV).
How Do Doctors Diagnose Interstitial Lung Disease?
Finding the cause of interstitial lung disease can be challenging, and sometimes the cause can't be found. Many conditions fall into the category of ILD, and in addition, the symptoms of a wide range of medical conditions can appear to be ILD. Healthcare professionals must rule out these other conditions before making a diagnosis.
Some of the following tests may be necessary:
Lab tests
Blood tests can detect proteins, antibodies, and other markers of autoimmune diseases or inflammatory responses to environmental exposures, such as those caused by molds or bird protein.
Imaging tests
Computerized tomography, also called a CT scan, is key to the diagnosis of interstitial lung disease. It's sometimes the first test in the diagnosis. CT scanners produce 3D images of internal structures. A high-resolution CT scan can be especially helpful in figuring out how much lung damage there is. It can show details of the fibrosis, which can help narrow the diagnosis and guide treatment decisions.
Echocardiogram uses sound waves to visualize the heart. It can create still images of the heart's structures and videos that show how the heart is working. This test can measure the amount of pressure in the right side of the heart.
Pulmonary function tests
Spirometry and diffusion capacity requires you to breathe out quickly and forcefully through a tube connected to a machine. The machine measures how much air your lungs can hold, how quickly you can move air out of your lungs, and how easily oxygen can move from your lungs into your bloodstream.
Oximetry places a small device on one of your fingers to measure the oxygen level in your blood. This test may be done at rest or with activity to monitor the course of the lung disease and figure out how serious it is.
Lung tissue analysis
Sometimes interstitial lung diseases can be diagnosed only by looking at a small amount of lung tissue in a lab — what's known as a biopsy. Your doctor or other healthcare professional may take a tissue sample using one of these methods:
Biopsy Method | How It Works | Limitations |
Bronchoscopy | A small, flexible tube called a bronchoscope is passed through the mouth or nose into the lungs to remove very small tissue samples, generally no larger than the head of a pin | Risks are generally minor (temporary sore throat, hoarseness), but samples are sometimes too small to make a diagnosis |
Bronchoalveolar lavage | About a tablespoon of sterile salt water is injected through a bronchoscope into a section of lung and suctioned out right away, collecting cells from the air sacs | Samples a larger area of the lung but may not give enough information to find the cause of pulmonary fibrosis |
Surgical biopsy | A more invasive procedure with potential complications; surgical instruments and a small camera are inserted through small incisions between the ribs while the surgeon views the lungs on a video monitor | Requires general anesthesia, but it's often the only way to get a large enough tissue sample to make the correct diagnosis |
Treatment Options for Interstitial Lung Disease
Lung scarring that already has occurred in interstitial lung disease can't be reversed, and treatment won't always stop the disease from getting worse. Some treatments may make symptoms better for a short time or slow the disease. Others help maintain quality of life.
Because many of the different types of scarring diseases have no approved or proven therapies, clinical trials may be an option to get an experimental treatment.
Medications
Intense research to find treatment options for specific types of interstitial lung disease is ongoing. Treatment may vary depending on the cause of ILD and what damage has happened in the lungs.
Medication Type | How It Helps | Notes |
Corticosteroid medicines | Prednisone is often the first treatment; sometimes other immune-suppressing drugs are used | Depending on the cause of ILD, these medicines may slow or even keep the disease from getting worse |
IPF-slowing medicines | Pirfenidone and nintedanib may slow the rate at which IPF worsens | Nintedanib is also approved for lung fibrosis that's getting worse due to other types of ILD; side effects are common for both drugs |
Stomach acid reducers | Treat gastroesophageal reflux disease (GERD), which affects most people with IPF and is linked to worse lung damage | If you have acid reflux symptoms, your healthcare professional may prescribe ways to reduce stomach acid |
Oxygen therapy
Using oxygen can't stop lung damage, but it can make it easier to breathe and exercise, prevent or lessen complications from low blood oxygen levels, lower blood pressure in the right side of the heart, and make sleep and sense of well-being better.
You're most likely to get oxygen when you sleep or exercise, although some people may use it around the clock.
Pulmonary rehabilitation
The aim of pulmonary rehabilitation is to make you better able to function and live a full, satisfying life. Pulmonary rehabilitation programs focus on learning more about your lung disease, exercise so you can be physically active for longer periods of time, breathing techniques that make your lungs more efficient, emotional support, and nutritional counseling.
Surgery
A lung transplant may be an option of last resort for some people with severe interstitial lung disease when other treatment options haven't helped.
Lifestyle and Home Strategies
You must be actively involved in your own treatment and stay as healthy as possible when living with interstitial lung disease.
Learn about your disease. Understanding your condition and how it can be treated can help you make decisions about your care. Including family members and friends can help them learn your needs.
Stop smoking. If you have lung disease, the best thing you can do for yourself is to stop smoking. Talk with your healthcare professional about options for quitting, including programs that use proven techniques. Because secondhand smoke can also harm your lungs, don't allow people to smoke around you.
Avoid exposure at work or during hobbies. When possible, stay away from substances that can irritate your lungs. Ask your healthcare professional for more information and advice.
Eat well. If you have lung disease, you may lose weight because it isn't comfortable to eat and because of the extra energy it takes to breathe. Aim to eat a nutritionally rich diet that contains enough calories. A dietitian can give you guidelines for healthy eating.
Get vaccinated. Respiratory infections can make symptoms of ILD worse. Make sure you get the pneumonia vaccine and a flu shot each year.
Coping and Emotional Support
Living with a chronic lung disease is emotionally and physically challenging. You may need to change your daily routines and activities — sometimes a lot — as breathing problems worsen or healthcare needs become more important. Feelings of fear, anger, and sadness are typical as you grieve for the loss of your old lifestyle and worry about what's next for you and your family.
Share your feelings with your loved ones and your healthcare professional. Talking openly may help you and your loved ones cope with the emotional challenges of your disease. Clear communication can also help you and your family plan for your needs if your disease gets worse.
Consider joining a support group, where you can talk with people facing challenges like yours. Group members may share coping strategies, exchange information about new treatments, or simply listen. If a group isn't for you, you may want to talk with a counselor in a one-on-one setting.
Preparing for Your Appointment
You'll probably first see your family healthcare professional about your symptoms. Your family healthcare professional may refer you to a pulmonologist, a doctor who specializes in lung diseases.
What you can do
Before your appointment, prepare answers to these questions:
Preparation Item | Examples |
Your symptoms | What they are and when they started |
Other medical conditions | Anything you're currently being treated for |
All medicines and supplements | Everything from the past five years, including over-the-counter medicines and street drugs |
All your occupations | Every job you've had, even if only for a few months |
Family lung disease | Any members of your family with a lasting lung disease of any kind |
Cancer treatments | Any past chemotherapy or radiation treatments |
Let your pulmonologist know if you've had any chest X-rays, CT scans, or other tests so the healthcare professional can request the results before your visit. The images are more important than the report alone. The pulmonologist can make a diagnosis by comparing an old imaging test with those of a current test.
What to expect from your doctor
Your doctor or other healthcare professional may ask questions such as:
Do your symptoms occur all of the time, or do they seem to go away and then come back?
Have you recently had contact with air conditioners, humidifiers, pools, hot tubs, or water-damaged walls or carpet?
Do you own any pet birds or feather-containing items such as down pillows or comforters?
Are you exposed to mold or construction dust in your home or other places where you spend a lot of time?
Have any close relatives, friends, or co-workers been diagnosed with a lung condition?
Do you have any family history of lung disease?
Does your work history include regularly working with or being around toxins and pollutants, such as asbestos, silica dust, or grain dust?
Do you or did you smoke? If so, how much and for how long? If not, have you spent a lot of time around others who smoke?
Have you been diagnosed or treated for any other medical conditions, particularly arthritis or rheumatic diseases?
Do you have symptoms of gastroesophageal reflux disease (GERD), such as heartburn?
Conclusion: Scarring Can't Be Undone — But Progression Can Be Slowed
Interstitial lung disease is a large family of conditions united by one problem: lung tissue that heals the wrong way, leaving behind thick, stiff scars that make breathing and oxygen exchange harder over time. The warning signs are simple — shortness of breath and a dry cough that don't go away — but the causes are surprisingly diverse, ranging from decades-old dust exposure to autoimmune disease to certain prescription medicines.
The honest reality is that existing scarring generally can't be reversed, and the disease may progress at an unpredictable pace. But that doesn't mean treatment is powerless. Drugs like pirfenidone and nintedanib can slow the worsening of some types, oxygen therapy and pulmonary rehabilitation restore day-to-day function, and removing the source of exposure can halt environmental forms entirely.
The single most important action you can take is to get breathing symptoms checked early. By the time symptoms appear in some ILD types, lasting lung damage has already occurred — and an early, correct diagnosis changes what treatment can achieve. If you have unexplained shortness of breath or a persistent dry cough, book an appointment with your doctor — a referral to a pulmonologist is often the next step. For more guides on lung health, breathing problems, and autoimmune conditions, explore the rest of Rinnit.com's respiratory and immune health library.
Frequently Asked Questions (FAQ)
1. What is interstitial lung disease in simple terms?
Interstitial lung disease (ILD) is a group of more than 200 conditions in which the lung tissue around the tiny air sacs becomes inflamed, scarred, and stiff. The scarring — called fibrosis — makes the lungs hard to expand and makes it difficult for oxygen to pass into the bloodstream, causing shortness of breath and a dry cough.
2. What are the main symptoms of interstitial lung disease?
The two main symptoms are shortness of breath at rest or shortness of breath that worsens with physical activity, and a persistent dry cough. Because many other conditions affect the lungs, an early and correct diagnosis is important for proper treatment.
3. Is interstitial lung disease curable?
No cure exists, and once lung scarring occurs it generally isn't reversible. Treatment focuses on keeping more scarring from occurring, managing symptoms, and improving quality of life. Some medicines may slow the damage, and lung transplant is an option for some people.
4. What causes the lung scarring in ILD?
ILD seems to occur when an injury to the lungs causes a healing response that isn't proper. The body normally creates just the right amount of tissue to repair damage, but in ILD the repair process doesn't work properly, leaving tissue around the air sacs inflamed, scarred, and thickened.
5. Can interstitial lung disease go away on its own?
In a few cases, yes — particularly hypersensitivity pneumonitis, which can improve by staying away from the airborne irritant such as bird protein or mold. But if exposure continues, the inflammation can worsen into more-lasting damage. Scarring from most other ILD types does not go away.
6. Is idiopathic pulmonary fibrosis the same as interstitial lung disease?
IPF is one specific type of ILD — the most common one. It's called "idiopathic" because the cause isn't known. IPF is typically progressive, shows on imaging and biopsy, often gets worse, and can't be reversed.
7. What is the difference between pneumoconiosis and hypersensitivity pneumonitis?
Pneumoconiosis comes from breathing in dust over a long time — coal dust (coal miner's lung), asbestos (asbestosis), or silica (silicosis) — and its symptoms can't be reversed. Hypersensitivity pneumonitis comes from breathing in airborne irritants such as bird protein, mold, or bacteria, and can improve if you stop the exposure.
8. How is interstitial lung disease diagnosed?
A high-resolution CT scan is the key imaging test, often the first in the process. Doctors also use blood tests, echocardiogram, spirometry with diffusion capacity, and oximetry. When those aren't enough, lung tissue samples are taken by bronchoscopy, bronchoalveolar lavage, or surgical biopsy — surgical biopsy is often the only way to get a large enough sample for a correct diagnosis.
9. What medicines treat interstitial lung disease?
Corticosteroids such as prednisone are often the first treatment. For idiopathic pulmonary fibrosis, pirfenidone and nintedanib may slow how fast the disease worsens — nintedanib is also approved for worsening lung fibrosis from other ILD types. Because acid reflux is linked to worse lung damage in IPF, stomach acid reducers may also be prescribed. Side effects are common, so discuss the pros and cons with your healthcare professional.
10. How serious are the complications of ILD?
ILD can lead to life-threatening complications: pulmonary hypertension (high blood pressure in the lung arteries), right-sided heart failure (cor pulmonale), and, in the end stage of chronic ILD, respiratory failure. Early diagnosis and treatment aim to delay or prevent these outcomes.
11. Can you prevent interstitial lung disease?
You can lower your risk by avoiding toxins at work (asbestos, coal dust, silica dust) and in the environment (bird protein, mold, bacteria), wearing a respirator when exposure is unavoidable, not smoking and avoiding secondhand smoke, and staying up to date on the pneumonia vaccine, annual flu shot, and other recommended vaccines such as pertussis, COVID-19, and RSV.
12. What should I bring to my ILD appointment?
Bring a full list of symptoms and when they started, every occupation you've ever had, all medicines and supplements from the past five years, and details of any past chemotherapy or radiation. If you've had chest X-rays or CT scans before, let your pulmonologist know — the actual images matter more than the report alone, because comparing old and current imaging helps the doctor make a diagnosis.
Further Reading
National Heart, Lung, and Blood Institute. Interstitial Lung Diseases. National Heart, Lung, and Blood Institute. March 24, 2022. https://www.nhlbi.nih.gov/health/interstitial-lung-diseases
American Lung Association. Interstitial Lung Disease (ILD). American Lung Association. Accessed October 30, 2026. https://www.lung.org/lung-health-diseases/lung-disease-lookup/interstitial-lung-disease
Pulmonary Fibrosis Foundation. Home. Pulmonary Fibrosis Foundation. Accessed October 30, 2026. https://www.pulmonaryfibrosis.org/
Sources
Mayo Clinic Staff. Interstitial lung disease - Symptoms and causes. Mayo Clinic. November 23, 2024. https://www.mayoclinic.org/diseases-conditions/interstitial-lung-disease/symptoms-causes/syc-20353108
Richeldi L, du Bois RM, Raghu G, et al. Efficacy and safety of nintedanib in idiopathic pulmonary fibrosis. N Engl J Med. 2014;370(22):2071-2082. PMID 24836310. https://doi.org/10.1056/NEJMoa1402584
King TE, Bradford WZ, Castro-Bernardini S, et al. A phase 3 trial of pirfenidone in patients with idiopathic pulmonary fibrosis. N Engl J Med. 2014;370(22):2083-2092. PMID 24836312. https://doi.org/10.1056/NEJMoa1402582
Related Reading
Learn more in our guide to Pulmonary Function Tests (PFTs): Types, Preparation and What Your Results Mean.
Learn more in our guide to Spirometry: What the Lung Function Test Measures, How It's Done and What Results Mean.
Lung Biopsy: Types, What to Expect, Recovery, Risks and Results explains the biopsy types used to sample lung tissue.
Medical Disclaimer
This article is for informational purposes only and does not constitute medical advice. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read here.
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