Bronchiolitis - Types, Symptoms, Causes And Risk Factors
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Bronchiolitis is a type of respiratory tract infection in infants and young children. Bronchiolitis causes inflammation to airways. It happens when tiny airways (also known as bronchioles) get infected by a virus. When the bronchioles become damaged or infected, they can swell or get clogged, ultimately blocking the oxygen flow. Bronchiolitis is known to be a childhood condition and more common in the winter season. Most cases of bronchiolitis can be treated at home with proper rest and medication.

What are the types of bronchiolitis?

There are two major types of bronchiolitis.

1. Viral bronchiolitis

Viral bronchiolitis is observed in infants. This type of bronchiolitis is caused by a respiratory syncytial virus (RSV). RSV outbreaks occur almost every winter season and infect children under the age of one year old.

2. Bronchiolitis obliterans

It is a rare and dangerous condition observed in adults. Bronchiolitis obliterans causes scarring in the bronchioles. This leads to an inflammatory obstruction in the airways that cannot be reversed.

What are the sign and symptoms of bronchiolitis?

Bronchiolitis initially starts with symptoms similar to those of a common cold. Later on, it progresses to coughing, wheezing, and difficulty in breathing. Signs and symptoms include:

  • Runny nose
  • Stuffy nose & congestion
  • Mild fever
  • Breath shortness
  • Cough
  • Wheezing
  • Bluish discoloration of skin due to lack of oxygen
  • Nasal flaring in infants
  • Cough
  • Fast breathing
  • Crackling/ rattling sounds heard in the lungs

What causes bronchiolitis?

Bronchiolitis occurs when a virus transmits the infection to bronchioles. The infection makes the bronchioles become inflamed and swell. This causes mucus collection in these airways, making it difficult for air to flow freely in the lungs.

Causes of viral bronchiolitis:

As the name suggests, viral bronchiolitis is caused by viruses. Respiratory syncytial virus (RSV) being the most common causative agent. It usually strikes children by the age of two, but it is most common in babies under one year old. Other known viruses that can cause bronchiolitis are adenoviruses and influenza viruses.

Causes of bronchiolitis obliterans:

Bronchiolitis obliterans may result from lung injury caused by a variety of different chemicals and respiratory infections. Inhaled chemicals known to irritate the lungs and lead to the condition include chlorine; ammonia; oxides of nitrogen or sulfur dioxide; welding fumes; or food flavoring fumes (such as diacetyl).

When to consult a doctor?

If it is difficult to eat or drink and breathing becomes more difficult in children, it is advised to visit a doctor. This is especially essential if the child is younger than 10-12 weeks old or has other risks of bronchiolitis. The following signs &symptoms are reasons to look for medical attention:

  • Audible wheezing sound
  • Rapid breathing rate
  • Labored breathing
  • Lethargic appearance
  • Refusal to drink enough or breathing too fast to eat and drink
  • Skin turning blue (cyanosis)

What are the risk factors of bronchiolitis?

Risk factors for viral bronchiolitis:

Viral bronchiolitis affects children up to two years old. But it is more common in infants (3 to 9 months old). Risk factors for viral bronchiolitis in babies include:

  • Not being breastfed
  • Premature birth
  • Baby born with specific heart or lung condition
  • Depressed immune system
  • Being exposed to cigarette smoke
  • Spending time in the crowded surrounding

Risk factors for bronchiolitis obliterans:

  • Exposed to harmful chemicals in the working environment
  • Had heart, lung, or bone marrow transplant
  • Smoking tobacco and nicotine
  • Having an autoimmune connective tissue disorder

What are the complications associated with bronchiolitis?

Mild bronchiolitis does not possess any complications. However, complications of severe bronchiolitis are:

  • Blue skin, especially lips and fingernails (cyanosis)
  • Apnea – Pause in breathing most likely to occur in premature babies
  • Dehydration
  • Low oxygen level
  • Respiratory failure

What preventions should be taken to avoid bronchiolitis?

Since bronchiolitis is a viral infection, its viruses can easily spread from one person to another. It is better to take preventions to avoid the infection. Preventive measures include:

  • Maintaining personal hygiene such as frequent handwashing before touching the infants, wearing a face mask, etc.
  • If the child has bronchiolitis, keep him/her isolated at home.

Other common preventions that help to curb bronchiolitis include:

  • Avoid contact with sick people
  • Keep the high touch surfaces clean and disinfect
  • Cover your mouth and nose during cough and sneeze
  • Don’t share personal items

Diagnosis of bronchiolitis

There are various methods to diagnose both types of bronchiolitis. A healthcare provider can usually identify the issue by observing the child and listening to the lungs with a stethoscope. However, if the symptoms are getting worse, the doctor may order the following tests:

  • Chest X-ray – Usually to look for any signs of pneumonia.
  • Mucus culturing – To identify and confirm the presence of the virus in the mucus.
  • Blood test – It might be used to check white blood cells as a rise in the numbers of WBCs is a sign that the body is fighting against an infection.

The doctor may also look for the signs of dehydration if the child has been refusing to eat or drink. Signs of dehydration in infants include sunken eyes, dry mouth, dry skin, no or significantly less urination, and sluggishness.

Note: Always consult your doctor before going for any test.

What is the difference between bronchiolitis and bronchitis?

Both the conditions not only sound familiar, but they are similar in many ways. Both are viral infections to the airways. The major difference between the conditions is that bronchiolitis affects the smaller airways (bronchioles), while bronchitis affects the larger airways (bronchi). Bronchiolitis is usually seen in infants and younger children, while bronchitis affects older children and adults.

Home care to curb bronchiolitis

  • Humidify the air
  • Keep the baby upright that makes the breathing easier
  • Give the child plenty of liquids to prevent dehydration
  • Maintain a smoke-free environment
  • To ease congestion, try saline nose drop

Medical Tests and Health Checkups Available At House of Diagnostics (HOD).


Data Sources:


Bronchiolitis - Types, Symptoms, Causes And Risk Factors
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Bronchiolitis - Types, Symptoms, Causes And Risk Factors
Bronchiolitis is a type of respiratory tract infection in infants and young children. Bronchiolitis causes inflammation to airways. It happens when tiny airways (also known as bronchioles) get infected by a virus.
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