Bronchiolitis is a common illness of the respiratory tract caused by an infection that affects the tiny airways, called the bronchioles, that lead to the lungs.

More to Know

Bronchiolitis is usually caused by a viral infection, most commonly respiratory syncytial virus (RSV). RSV infections are responsible for more than half of all cases of bronchiolitis and are most widespread in the winter and early spring. Other viruses associated with bronchiolitis include rhinovirus, influenza (flu), and human metapneumovirus.

The infections that cause bronchiolitis are contagious. The best way to prevent the spread of viruses that can cause bronchiolitis is frequent hand washing. It may help to keep infants away from others who have colds or coughs, and away from cigarette smoke.

Keep in Mind

Fortunately, most cases of bronchiolitis are mild and require no specific professional treatment. The best treatment for most cases is time to recover and plenty of fluids.

All A to Z dictionary entries are regularly reviewed by KidsHealth medical experts.