Lung diseases are some of the most common medical conditions in the world. Tens of millions of people suffer from lung disease in the U.S. Smoking, infections, and genetics are responsible for most lung diseases.

The lungs are part of a complex apparatus, expanding and relaxing thousands of times each day to bring in oxygen and expel carbon dioxide. Lung disease can result from problems in any part of this system.

Pneumonia: An infection of the alveoli, usually by bacteria.
Tuberculosis: A slowly progressive pneumonia caused by the bacteria Mycobacterium tuberculosis.
Emphysema results from damage to the fragile connections between alveoli. Smoking is the usual cause. (Emphysema also limits airflow, affecting the airways as well.)
Pulmonary edema: Fluid leaks out of the small blood vessels of the lung into the air sacs and the surrounding area. One form is caused by heart failure and back pressure in the lungs' blood vessels; in another form, direct injury to the lung causes the leak of fluid.
Lung cancer has many forms, and may develop in any part of the lungs. Most often this is in the main part of the lung, in or near the air sacs. The type, location, and spread of lung cancer determines the treatment options.
Acute respiratory distress syndrome (ARDS): Severe, sudden injury to the lungs caused by a serious illness. Life support with mechanical ventilation is usually needed to survive until the lungs recover.
Pneumoconiosis: A category of conditions caused by the inhalation of a substance that injures the lungs. Examples include black lung disease from inhaled coal dust and asbestosis from inhaled asbestos dust.

The most common symptom of all forms of interstitial lung disease is shortness of breath. Nearly all people with interstitial lung disease will experience breathlessness, which may get worse over time.

Other symptoms of interstitial lung disease include:

Cough, which is usually dry and nonproductive.
Weight loss, most often in people with COP or BOOP.

In most forms of interstitial lung disease, the shortness of breath develops slowly (over months). In interstitial pneumonias or acute interstitial pneumonitis, symptoms come on more rapidly (in hours or days).

Treatments for interstitial lung disease vary according to the type of interstitial lung disease and its cause.

Antibiotics . These are effective treatments for most interstitial pneumonias. Azithromycin (Zithromax) and levofloxacin (Levaquin) eliminate the bacteria that cause most interstitial pneumonias. Viral pneumonias usually resolve on their own. Fungal pneumonias are rare, but can be treated with antifungal drugs.

Corticosteroids: In some forms of interstitial lung disease, ongoing inflammation in the lungs causes damage and scarring. Corticosteroids like prednisone and methylprednisolone reduce the activity of the immune system. This reduces the amount of inflammation in the lungs and the rest of the body.

Inhaled oxygen: In people with low oxygen blood levels due to interstitial lung disease, inhaled oxygen may improve symptoms. Regular use of oxygen might also protect the heart from damage caused by low oxygen levels.

Lung transplant : In advanced interstitial lung disease causing severe impairment, a lung transplant may be the best option. Most people undergoing lung transplant for interstitial lung disease make large gains in quality of life and their ability to exercise.

Azathioprine (Imuran): This drug also suppresses the immune system. It has never been proven to improve interstitial lung disease, but some studies suggest it might help.


N-acetylcysteine (Mucomyst): This potent antioxidant may slow the decline of lung function in some forms of interstitial lung disease. It should not be used alone.

Other treatments not used as often for interstitial lung disease include:

Cyclophosphamide (Cytoxan)
Methotrexate
Cyclosporine
Pirfenidone (Exbriet)

Nintedanib (OFEV)

People with interstitial lung disease usually come to see a doctor due to concern about shortness of breath or cough. Imaging tests of the lungs are usually done to identify the problem.

Chest X-ray: A simple chest X-ray is the first test in the evaluation of most people with a breathing problem. Chest X-ray films in people with interstitial lung disease may show fine lines in the lungs.


Computed tomography (CT scan): A CT scanner takes multiple X-rays of the chest and a computer creates detailed images of the lungs and surrounding structures. Interstitial lung disease can usually be seen on a CT scan.

High-resolution CT scan: If interstitial lung disease is suspected, using certain CT scanner settings can improve the images of the interstitium. This increases the CT scan's ability to detect interstitial lung disease.

Pulmonary function testing: A person sits in a sealed plastic booth and breathes through a tube. People with interstitial lung disease may have a reduced total lung capacity. They may also have a decreased ability to transfer oxygen from their lungs into their blood.