Bronchiolitis: Symptoms & Signs

Medically Reviewed on 9/10/2019

Bronchiolitis is inflammation of the bronchioles, or small airways, of the lungs. The effects of bronchiolitis are most pronounced in children under age 2. The condition is most common during the winter months.

Signs and symptoms of bronchiolitis include fast breathing or difficulty breathing, shallow breathing, shortness of breath, wheezing, nasal congestion, and watery nasal discharge. Other associated symptoms of bronchiolitis can include sore throat, dehydration, loss of appetite, malaise, and coughing. Fever is not a common symptom unless the infection becomes severe.

Causes of bronchiolitis

A viral infection most commonly causes bronchiolitis. Respiratory syncytial virus (RSV) is the most common viral infection that causes bronchiolitis and is a highly contagious infection. This is most commonly occurs in young children.

Other bronchiolitis symptoms and signs

  • Coughing
  • Dehydration
  • Difficulty Breathing
  • Loss of Appetite
  • Malaise
  • Nasal Congestion
  • Shallow Breathing
  • Shortness of Breath
  • Sore Throat
  • Watery Nasal Discharge
  • Wheezing


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Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.