Wheezing in infants and young children

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Wheezing is a relatively high-pitched whistling sound that occurs during breathing when the airways are partially blocked or narrowed.

Wheezing is caused by a narrowing of the airways.
Other symptoms depend on the cause and may include cough, fever, and runny nose.
The diagnosis of the cause is based on chest x-rays and sometimes other tests.
Treatment can include bronchodilators and corticosteroids.

(See also Wheezing in adults.)
Wheezing is caused by a narrowing or blockage (obstruction) of the airways. The narrowing can be caused by one or more of the following:

Swelling of the tissues in the airways
Spasm of the tiny muscles in the walls of the airways (bronchospasm)
Accumulation of mucus in the airways

Recurring episodes of wheezing are common in the first few years of life. Until recently, doctors diagnosed these episodes as asthma because, like asthma, episodes could be relieved by inhaling drugs that open the airways (bronchodilators) and because most adults who have asthma first developed symptoms in childhood. Now, however, doctors know that only some infants and young children who have such episodes of wheezing have asthma in later childhood or adolescence.
Children who are more likely to be eventually diagnosed with asthma include children who have one or more of the following risk factors:

Certain rashes (such as eczema)
More severe wheezing episodes
Family members with asthma
A family tendency to have many allergies
Wheezing with viral illnesses (particularly those caused by respiratory syncytial virus and human rhinovirus)

However, in most children, wheezing episodes stop by 6 to 10 years of age, and doctors do not diagnose these children as having asthma. Such children have other causes for their recurring episodes of wheezing.