Infant wheezing: Is it asthma?

Not necessarily. Wheezing — a high-pitched, whistling kind of noise that comes from the airways, typically the lower airways — is a classic sign of asthma. However, not every child who wheezes will develop asthma, and not every child with asthma wheezes.

Wheezing commonly occurs in infants and young children with certain viral infections. This is because their airways are so small that any airway infection can cause breathing difficulties. Up to 50 percent of infants have at least one episode of wheezing before they're 3 years old. But only about one-third of these children will develop asthma before age 6 years.

Diagnosing asthma in infants may be difficult. In older children and adults, special breathing tests (lung function tests) can be used to make a diagnosis. But these tests are less practical in very young children because they require cooperation and understanding to get good results. Children usually don't develop these skills until the time they're 4 years old.