Los Angeles ? Steroid drugs, a common treatment for young children prone to wheezing and colds, do not help and may even be harmful, according to new research.

Preschoolers in Britain who were hospitalized with a wheezing attack and treated with the steroid prednisolone stayed just as long as other children who were given dummy pills.

In another study, Canadian children who had previous wheezing trouble and who took the steroid fluticasone as a preventive measure showed modest improvement, but the side effect of possible stunted growth outweighed the benefit, researchers said.

Both studies were reported in today’s New England Journal of Medicine.

“It is disturbing to contemplate how many unnecessary courses of prednisolone have been given over the years, in good faith, because we all assumed that preschool children are little adults,” Dr. Andrew Bush of the Royal Brompton Hospital in London wrote in an accompanying editorial.