Asthma  -- a chronic inflammatory condition characterized by spasm, or narrowing, of the airways  -- affects about 5 million children in the United States, and it's on the rise. Doctors may shy away from diagnosing it until a child is 4  -- they call it recurrent "bronchitis" or "bronchiolitis"  -- because about half of these kids outgrow it; they'll never get asthma.

But there's growing evidence not only that early treatment provides immediate symptomatic relief but that giving a child of 4 or under inhaled corticosteroid drugs reduces the risk of lung damage in these kids, says pediatric pulmonologist Susan Millard, M.D., of DeVos Children's Hospital, in Grand Rapids. It also makes sense to schedule a visit to a pediatric allergist or pulmonologist who can identify triggers so families can take smart steps to protect lungs early.

Asthma in preschoolers is increasingly common yet remains seriously underdiagnosed, says Dr. Millard. This may be in part because of the myth that asthma always involves wheezing. A persistent cough when there's no cold or other respiratory infection is a red flag  -- especially if it comes on with exercise or laughing.

It's up to you to bring such a pattern to the attention of the pediatrician, who otherwise might dismiss the cough as an isolated symptom of a cold. If you think it may be asthma, ask for a referral to a pediatric pulmonary specialist and an allergist.

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