Last Updated 05/06/2020

Author:Marc Feinstein, MD, FCCP

About Bronchiolitis

Key facts about Bronchiolitis
  • Bronchiolitis happens when the small airways in your lungs become injured or inflamed.
  • Bronchiolitis has many causes, including breathing in strong irritants, having an infection, and taking some medications.
  • Treatment of bronchiolitis depends on its cause. It also depends on how much injury has been done to your lungs.

Bronchioles connect your small airways, or bronchi, to tiny air sacs in your lung, called alveoli. When these bronchioles are injured or swollen, the result is called bronchiolitis.

Swelling, or Inflammation, in your airways can happen for many reasons, including:

  • Infections;
  • Medications;
  • Bone marrow, stem cell, lung, and other transplants;
  • Some types of arthritis; and
  • Exposure to any strong lung irritant, such as acids and toxic fumes.

How Bronchiolitis affects your body

Regardless of the cause, the small airways of the bronchioles become narrow, blocking the airway. This blockage may cause shortness of breath and cough. These symptoms are similar to other common lung diseases, including asthma and chronic obstructive pulmonary disease (COPD).

How serious is Bronchiolitis?

Bronchiolitis is a common lung condition in the United States. The most common causes are viral respiratory infections. Young children are the most commonly affected because they can get lung infections that they may not be able to fight off as well as adults.

How serious bronchiolitis is depends on how severe the damage to the lung is. It also depends on how long the damage lasts.

For cases related to infection, bronchiolitis often heals completely. If it results from a toxic exposure, such as inhaling acid, some symptoms can be permanent.

In rare situations, such as when bronchiolitis occurs after transplants, it may result in death or the need for lung transplant.

Often, bronchiolitis requires treatment. Commonly used medications include anti-inflammatory corticosteroids.

Symptoms of Bronchiolitis

Not everyone with bronchiolitis will have symptoms. Symptoms are often related to inflammation in the small airways. Symptoms like shortness of breath and cough are common. When symptoms are caused by an irritating substance, people may experience irritation in other parts of the body, including the eyes, nose, and throat.

What causes Bronchiolitis?

Bronchiolitis is the result of injury to the small airways in the lung. Bronchiolitis is a general term to describe lung damage. This damage can be caused by many things. For example, bronchiolitis that occurs after breathing in a toxic substance is caused by direct damage to the small airways. Bronchiolitis that occurs with arthritis is caused by the immune system’s effect on the small airways.

What are risk factors for Bronchiolitis?

A person is at higher risk for developing bronchiolitis whenever they get a respiratory infection, breathe an irritant, or have a medical condition where injury to the bronchioles may occur. Categories of risk factors include:

  • Infections. Infections include common cold viruses, influenza, measles and some forms of pneumonia. Young children are most at risk for this type of bronchiolitis.
  • Inhaling toxic substances. Such substances include acid, chlorine, ammonia, and smoke.
  • Medications. Gold, penicillamine, sulfasalazine, and rituximab can all cause bronchiolitis.
  • Arthritis. Forms of arthritis, including rheumatoid arthritis and lupus, can cause bronchiolitis.
  • Organ transplantation. Transplant of organs, stem cells, and bone marrow can cause bronchiolitis.

Diagnosing Bronchiolitis

To diagnose bronchiolitis, your health care provider will ask you many questions. You can expect questions about where you live, where you may have traveled, and whether you have been exposed to certain chemicals or medications.

To diagnose bronchiolitis, your provider must rule out other medical problems, which may require further testing. Tests may include lung function tests. These tests require you to do breathing exercises, most often blowing into a tube or holding your breath for a short period of time. Another test often used in this situation is a computed tomography (CT) scan. CT scans are a form of X-ray that produces images of your lungs. These images can help doctors decide if you have bronchiolitis. They may also help your provider determine what type of bronchiolitis it may be.

If these do not help your provider determine whether you have bronchiolitis, your doctor may want a biopsy, or a small tissue sample, of your lungs to figure it out.

How Bronchiolitis is diagnosed

Bronchiolitis may be a difficult diagnosis to make. Your health care provider may be able to diagnose it if there is a clear risk factor and your lung function testing or CT images show damage. However, it is usually considered when people do not respond well to treatment for more common lung diseases like asthma or emphysema. Many people require a lung biopsy. Looking at small samples from the damaged lung through the microscope is the most accurate way to diagnose bronchiolitis. That knowledge will help guide your provider toward the best treatment.

When should you see your health care provider?

Contact your health care provider if you experience:

  • Coughing and breathlessness that do not go away; or
  • Coughing and breathlessness after a respiratory infection or inhaling a toxic substance.

Treating Bronchiolitis

The most common treatments are medications to help control symptoms. For instance, cough medications are used to suppress the cough. Inhalers are used to help with shortness of breath.

Other treatments depend on the cause of injury to the airways. When bronchiolitis is caused by medication or inhaling a toxic substance, limiting exposure can reduce symptoms. When bronchiolitis is the result of a disease, such as arthritis, treatment may include medications against those diseases.

When you have severe symptoms, your health care provider may prescribe steroids. Steroids are strong medications used to fight inflammation. They work by suppressing the immune system. These medications are often effective, but they also have side effects, including increased appetite, increased blood sugar levels, and weight gain.

Managing Bronchiolitis

Most people with bronchiolitis lead active lives without many health problems. Bronchiolitis may go away by itself, with medication, or by avoiding harmful substances.

People with severe or worsening symptoms may need to take medications. Many factors can cause bronchiolitis, so it’s not always possible to predict whether any single medication will work. Medications that may be used include:

  • Albuterol. This is an inhaled medication most commonly used for asthma. Albuterol can help with symptoms by opening the airways.
  • Corticosteroids. These medications work by suppressing the immune system to reduce inflammation. Side effects of corticosteroids include increased appetite, weight gain, and high blood sugar levels.
  • Macrolide antibiotics. These antibiotics fight inflammation and help manage some lung diseases.

Rarely, some people require a lung transplant.


Bronchiolitis is relatively common. Ask your health care provider for more information. The American Lung Association recommends that patients and caregivers join their Living with Lung Disease support community. Here, you can connect with others facing this disease. You can also call the American Lung Association’s Lung Help Line at 1-800-LUNGUSA to talk to a trained lung professional. They can help answer your questions and connect you with additional support.

Questions and answers about Bronchiolitis

  • How common is bronchiolitis?

    Bronchiolitis is common among young children. However, no one knows exactly how many adults have it. Because bronchiolitis is most often caused by viral infections, it may get better by itself before it is ever diagnosed. Some of the uncertainty is because bronchiolitis is probably not a single disease. Rather, it’s a type of lung injury that has several causes. Bronchiolitis appears to be less common than asthma, emphysema, or bronchitis.

  • Will symptoms of bronchiolitis ever go away?

    It depends on what caused the bronchiolitis in the first place. If bronchiolitis began after an infection or inhaling something irritating, most people recover fully. Symptoms usually improve by staying away from that substance or taking medications.

    With more severe lung injury, permanent changes may appear on breathing tests and X-rays, even when symptoms have gone away.

    When bronchiolitis is caused by another illness, such as arthritis, symptoms can be much harder to control. In this case, symptoms may never go away entirely.

    For people with bronchiolitis obliterans, a severe form that often happens after an organ or stem cell transplant, bronchiolitis may require many medications and eventually lung transplant.

  • What types of substances can cause bronchiolitis through sudden exposure?

    Generally, these are industrial chemicals that dissolve easily in water. Among them are acids, bleaches, and ammonia. Many of these exist in strong cleaning fluids. Some forms of these chemicals are found in machines we use every day, such as battery acids in cars.

    With more severe lung injury, permanent changes may appear on breathing tests and X-rays, even when symptoms have gone away.

    When bronchiolitis is caused by another illness, such as arthritis, symptoms can be much harder to control. In this case, symptoms may never go away entirely.

    For people with bronchiolitis obliterans, a severe form that often happens after an organ or stem cell transplant, bronchiolitis may require many medications and eventually lung transplant.

  • What are some side effects of medications used to treat bronchiolitis?

    Albuterol, an inhaled medication used for asthma, can cause the heart rate to speed up. Frequent users may experience a mild tremor in the hand. Corticosteroids work by suppressing the immune system. Therefore, people who take them may be more likely to get infections. Other side effects from steroids include increased appetite, weight gain, and higher sugar levels.

    The macrolide antibiotic most often used is azithromycin, commonly called “Z-pack.” Macrolides don’t typically have many side effects but can cause stomach upset. They can also cause changes to your heart rate (measured by electrocardiogram, or ECG) or to hearing. Health care providers who prescribe macrolides for long periods may check your ECG and recommend hearing tests about once a year.