An Overview of Bronchiolitis Obliterans

Doctor examining and commenting patient's lungs X-ray.
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Bronchiolitis obliterans is a serious, irreversible lung disease that is also known as obliterative bronchiolitis and popcorn lung. The most common effects of bronchiolitis obliterans include coughing and shortness of breath.

It is often caused by exposure to toxins and it can also develop after a lung or bone marrow transplant. Bronchiolitis obliterans causes symptoms similar to those of chronic obstructive pulmonary disease (COPD) or asthma, and diagnostic tests can help distinguish these illnesses from each other.

While there is no cure for bronchiolitis obliterans, there are treatments that can help manage the effects. Sometimes treatment with a lung transplant may be considered when the condition is caused by toxin exposure.

Symptoms of Bronchiolitis Obliterans

Generally, bronchiolitis obliterans is a disease that affects adults, but it can affect children and adolescents too. The effects generally develop over the course of a few weeks or months and may cause significant distress in your day to day life.

The most common symptoms of bronchiolitis obliterans are:

  • A dry cough
  • Wheezing (a loud raspy sound when breathing)
  • Dyspnea (shortness of breath)
  • Fatigue and low energy

Once the condition begins, the effects typically worsen. In general, the symptoms are constant, persistent, and are unrelated to factors such as weather (unlike asthma, which is characterized by exacerbations).

Because bronchiolitis obliterans affects breathing, you are likely to experience exercise intolerance with this condition. You may feel extremely short of breath and exhausted after moderate physical exertion.

Complications and Prognosis

If you have bronchiolitis obliterans, you are at an increased risk of developing lung infections, such as pneumonia or bronchitis. With bronchiolitis obliterans, these infections may become severe and can make your baseline respiratory symptoms substantially worse than usual.

Bronchiolitis obliterans, like COPD, eventually leads to respiratory failure, which is a severely impaired ability to breathe enough air to supply the body with adequate oxygen. Eventually, this condition can lead to premature death.

Associated Effects

Because bronchiolitis obliterans often develops in response to toxin exposure or as a transplant complication, you may experience other associated symptoms.

For example, toxin exposure can also cause problems such as a skin rash in addition to your respiratory impairment. A lung or bone marrow transplant may also be associated with complications of chemotherapy (such as loss of appetite and decreased immunity)—and you may experience these problems along with bronchiolitis obliterans.


Bronchiolitis obliterans is typically preceded by a respiratory illness, toxin exposure, or lung or bone marrow transplant. Severe inflammation in the lungs is believed to cause the condition.

The most common triggers include:

About 10% of people who receive a bone marrow transplant from a donor develop bronchiolitis obliterans within five years of the transplant procedure, while approximately 50% of lung transplant recipients develop the condition within five years.

Scarring and Inflammation of the Bronchioles

The bronchioles are tiny tubes in the lungs that carry air. When air cannot pass through the bronchioles to the alveoli (air sacs), the body's oxygen absorption becomes impaired.

Bronchioles can become damaged as a result of an infection, toxins, or inflammation. As they heal, the bronchioles may become permanently scarred. The thick scar tissue essentially "obliterates" the airway, blocking the bronchioles and preventing air from passing through.

Popcorn Lung

Bronchiolitis obliterans earned the nickname "popcorn lung" after an outbreak affected a group of people who worked in a popcorn production plant. The cause was traced to inhalation of diacetyl, a chemical that was used to give microwave popcorn its buttery flavor.


There are a number of causes of shortness of breath and wheezing, many of which are more common than bronchiolitis obliterans. This condition causes symptoms similar to those of chronic obstructive pulmonary disease (COPD) and asthma. The treatment of bronchiolitis obliterans is different than the treatment of other respiratory conditions, so getting an accurate diagnosis is essential.

Your medical history will typically provide the biggest clue that you could have bronchiolitis obliterans. If you have had a lung or bone marrow transplant, or if you have been exposed to a toxin (especially industrial toxins), it is important that you tell your doctor.

Your physical examination is an important part of your evaluation. Your doctor will listen to your breathing sounds with a stethoscope and can detect sounds such as wheezing, which are indicative of lung disease.

Diagnostic Tests

You may need to have some diagnostic tests to help assess your respiratory function. These tests can assess the severity of your condition and can help distinguish bronchiolitis obliterans from illnesses such as COPD, asthma, cancer and heart disease.

  • Imaging tests: Your medical team can assess the structure of your lungs with a chest X-ray or CT scan of the chest.
  • Pulmonary function tests: Non-invasive tests such as forced expiratory volume (FEV1) and forced vital capacity (FVC) measure the amount of air that you can breathe in and out.
  • Lung biopsy: With a surgical lung biopsy, your surgeon removes a small piece of tissue from your lung to examine it under a microscope. This is considered an accurate way to diagnose bronchiolitis obliterans. However, this test poses some risks, and it is not always safe after a lung transplant.

When you have bronchiolitis obliterans, your lung function may decline slowly over time, so you may need to have some of your medical tests repeated as your health care team assesses your disease progression and the effectiveness of your treatment.


While bronchiolitis obliterans is irreversible, there are treatments that can help prevent the progression of the disease and reduce your symptoms. If possible, be sure to avoid exposure to the precipitating toxin to avoid additional damage to your lungs.

It is important to be aware that bronchiolitis obliterans is expected to progress—even if you are no longer exposed to the precipitating factor. It can be fatal if left untreated.

Medications, including corticosteroids and other immunosuppressants (drugs that reduce the body's immune response), can reduce inflammation. This may help prevent further scarring and disease progression. This strategy may be considered regardless of the trigger that caused you to develop bronchiolitis obliterans.

Symptomatic Treatment

Your doctor may prescribe an inhaler for you to use. This can help alleviate your shortness of breath and wheezing. You may also be advised to use a cough suppressant if your cough is bothersome or interfering with your sleep or quality of life.

If you develop complications, such as pneumonia or bronchitis, you may need antimicrobial treatment, such as antibiotics or antifungal medications.

For late-stage bronchiolitis obliterans, you may need oxygen supplementation. Some people receive oxygen using a nasal cannula or a face mask. If you have advanced disease, mechanical ventilation may be necessary.

Lung Transplant

In some instances, a lung transplant is considered. This is major surgery. Of course, if you developed bronchiolitis obliterans as a complication of a lung transplant, another transplant might be difficult for you to physically tolerate.

A Word From Verywell

Bronchiolitis obliterans, an irreversible lung disease that develops as a complication of lung damage, progresses over a few weeks or months.

If you develop chronic lung disease, it can be difficult to exercise or to maintain moderate physical activity. It is beneficial to stay active, however. Physical therapy and pulmonary rehabilitation can be helpful in helping you maintain a healthy level of physical activity, which is an important aspect of staying healthy, even with chronic disease.

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