A new study has found that children who use certain types of asthma inhalers end up shorter than normal in adulthood.

The study, published this week in the New England Journal of Medecine, looked at over 1,000 children from ages 5 to 12 who were treated for asthma through the Childhood Asthma Management Program (CAMP) clinical trial. The children were split into three groups, one that used asthma inhalers with budesonide, one that used inhalers without budesonide, and one that used a placebo. Researchers followed up with the children until they were of adult height, 18 years old for girls and 20 years old for boys.

The findings show that those children who used inhalers with budesonide were an average of half-an-inch shorter than their peers when fully grown. It has long been known that budesonide, an inhaled corticosteroid, slowed growth in children. These new findings are the first evidence that the stunted growth sticks with children into adulthood.

“This was surprising because in previous studies, we found that the slower growth would be temporary, not affecting adult height,” said Dr. Robert Strunk, professor of pediatrics at Washington University School of Medicine and lead author of the study. “But none of those studies followed patients from the time they entered the study until they had reached adult height.”

The study controlled for gender, ethnicity, allergies, age at the start of the trial, severity of asthma symptoms, and the height of the parents. Strunk keeps careful track of inhaled steroid use by the children he treats at the St. Louis Children’s Hospital, but also downplayed the side-effect of lowered height.

“If a child is not growing as they should, we may reduce their steroid dose,” Strunk says. “But we think that the half-inch of lowered adult height must be balanced against the well-established benefit of inhaled corticosteroids in controlling persistent asthma. We will use the lowest effective dose to control symptoms to minimize concerns about effects on adult height.”