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What Is Bronchiolitis?

Bronchiolitis is a viral respiratory condition that affects the smallest air passages in the lungs, the bronchioles. The job of these small, branching bronchioles is to control airflow in your lungs. When they become infected or damaged, they swell or become clogged. This blocks the flow of oxygen. Although it’s generally a childhood condition, bronchiolitis can affect adults as well. 

What Are the Types of Bronchiolitis?

 Type 1

There are two types of bronchiolitis.

Viral bronchiolitis appears primarily in infants. Most cases of viral bronchiolitis are due to the respiratory syncytial virus (RSV). Viral outbreaks occur every winter and affect most children under the age of 1 year old.

Bronchiolitis obliterans is a rare and dangerous condition seen in adults. With this disease, scarring of the bronchioles blocks the air passages creating an airway obstruction that can’t be reversed. 

What Are the Symptoms of Bronchiolitis?


Both viral bronchiolitis and bronchiolitis obliterans have similar signs and symptoms. These include: 

  • shortness of breath
  • wheezing
  • a bluish appearance of the skin from lack of oxygen
  • crackling or rattling sounds heard in the lungs
  • fatigue
  • ribs that appear sunken during attempts to inhale (in children)
  • nasal flaring (in babies)
  • fast breathing
  • whooping cough 

The symptoms of bronchiolitis obliterans can occur two weeks to a little over a month after exposure to chemicals. A lung infection can take several months to several years to produce symptoms.

What Causes Bronchiolitis?


Causes of Viral Bronchiolitis

Viruses that enter and infect the respiratory tract cause viral bronchiolitis. Viruses are microscopic organisms that can reproduce rapidly and challenge the immune system. The following are common types of viral infections that may cause bronchiolitis:

Respiratory Syncytial Virus (RSV)

RSV is the most common cause of bronchiolitis. RSV usually strikes babies less than 1 year of age. This contagious and dangerous viral infection produces inflammation, mucus, and swelling in the airways.


These viruses target mucous membranes and cause approximately 10 percent of acute respiratory tract infections in children.

Influenza Viruses

These viruses cause inflammation in the lungs, nose, and throat. Influenza affects both adults and children. It’s especially dangerous for babies who don’t have strong immune systems.

Causes of Bronchiolitis Obliterans 

This rare condition sometimes occurs for no known reason. Severe cases can lead to death if they’re left untreated. A few causes have been identified and include: 

  • fumes from chemical agents such as ammonia, bleach, and chlorine
  • respiratory infections
  • adverse reactions to medications

Who Is at Risk for Bronchiolitis?

Risk Factors

Viral bronchiolitis can affect children younger than 2 years old, but it generally occurs in infants from 3 to 9 months of age. A few risk factors for viral bronchiolitis in babies and young children are: 

  • not being breast-fed
  • being born prematurely or born with a heart or lung condition
  • having a depressed immune system
  • being exposed to cigarette smoke
  • being in crowded places where the virus may be present, such as daycare centers

Common risk factors for bronchiolitis obliterans in adults are:

  • working conditions that expose you to dangerous chemicals
  • a heart, lung, or bone marrow transplant
  • a connective tissue disease

How Is Bronchiolitis Diagnosed?


There are several ways to diagnose both types of bronchiolitis. Imaging testing, including chest X-rays, typically helps diagnose bronchiolitis in both adults and children. A common tool used for adults is spirometry, which measures how much and how quickly you take in air with each breath. Blood gas tests for both bronchiolitis conditions measure how much oxygen and carbon dioxide are in your blood. 

Samples of mucus or nasal discharge can help your doctor diagnose the type of virus causing the infection. This testing method is common with babies and small children.

How Is Bronchiolitis Treated?


Viral bronchiolitis requires different treatments than bronchiolitis obliterans.

Treatments for Viral Bronchiolitis 

Many cases of viral bronchiolitis are so mild that they clear up on their own without treatment. However, as this condition most often affects infants, hospitalization may be necessary for more severe cases. A hospital can provide any needed oxygen and intravenous fluid treatments. Antibiotic medications are useless against viruses, but some medications can help open your baby’s airways.

Treatments for Bronchiolitis Obliterans

There’s no cure for the scarring in bronchiolitis obliterans. Corticosteroids can help clear the lungs of mucus, reduce inflammation, and open up the airways. You may need oxygen treatments and medications to boost the immune system. Breathing exercises and stress reduction can help ease breathing difficulties. A lung transplant may be the best option for the most severe cases of lung damage.

Home Care 

Both conditions require extra rest and increased fluid intake. Keeping the air in your home clear of smoke and chemicals is very important. A humidifier to keep the air moist may also help.

What Is the Long-Term Outlook?


Children and babies with viral bronchiolitis usually improve within a week with prompt, proper treatment. The outlook for someone with bronchiolitis obliterans depends on when the condition was found and how far it has progressed.

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