Using inhaled steroids to treat asthma in young children does not alter the course of the disease and should not be used for that purpose, according to two studies in The New England Journal of Medicine.

Inhaled steroids, such as Pulmicort (budesonide) and Flovent (fluticasone) reduce swelling and inflammation in the airways and help control the wheezing and breathlessness associated with asthma, which affects nearly 9 million children in the United States.

But some doctors prescribe them to very young children considered at risk of developing asthma in the hope of preventing the disease from developing. That strategy won’t work and should be discouraged because there could be risks associated with the drugs, researchers said in Thursday’s edition of the journal.

Concerns about inhaled steroids emerged after some studies found that the drugs slowed physical growth.

“Inhaled corticosteroids do not alter the natural history of the disease,” Harvard Medical School’s Diane Gold and Anne Fuhlbrigge said in an editorial. “The risk of wheezing will persist beyond the first years of life.”

One of the latest studies tested 285 children aged 2 and 3, with symptoms of asthma. During the two years they were treated, those taking the inhaled drugs had more symptom-free days.

But the following year, when treatment was suspended, those who had received the drugs fared no better than those who had received a placebo.

A separate study of 411 infants, conducted at Copenhagen University Hospital in Denmark Dr. Hans Bisgaard and his colleagues, found it made no difference whether the 1-month-old infants who had experienced a 3-day episode of wheezing received a corticosteroid or a placebo. The chance of developing a persistent wheeze - believed to be an early sign of asthma - was the same.

“Such drugs should not be used in the hope of altering the course of asthma in childhood,” said Gold and Fuhlbrigge. “Given the potential risks of therapy in early life, prolonged treatment for toddlers under the age of 2 years should be highly selective.”