Inhaled corticosteroids may cause children with mild to moderate persistent asthma to stop growing, by up to half a centimeter, during the first year of treatment, a pair of new studies finds. This effect was not cumulative over ensuing years, and researchers believe lowering the dosage may contribute to minimal side-effects.

Asthma is one of the most common chronic ailments that kids face. To offset the swelling found in the body’s airways, which prevent the lungs from filling with air, people turn to an inhaler. The device delivers anti-inflammatory medicine directly into a person’s respiratory system, calming the inflamed tubes and letting breathing resume. But out of the 25 trials the researchers examined, only 14 tracked children’s growth — a gross undervaluing of a problem they say needs serious attention.

“This is a matter of major concern given the importance of this topic," Francine Ducharme, co-author and researcher at the Department of Pediatrics at the University of Montreal, said in a statement. "We recommend that the minimal effective dose be used in children with asthma until further data on doses becomes available.”

Ducharme and her colleagues performed two separate reviews. The first involved 8,471 children up to 18 years old with mild to moderate asthma. The trials looked at all but one available corticosteroid, each one showing a marked suppression of subjects’ growth rates over the first year. This was with daily treatment, which amounted to kids growing roughly half a centimeter shorter than the annual average of six to nine centimeters.

On the other hand, said lead author of the review, Linjie Zhang, “this effect is less pronounced in subsequent years, is not cumulative, and seems minor compared to the known benefits of the drugs for controlling asthma and ensuring full lung growth." The effects, in other words, may not be compelling enough to quit asthma treatment altogether. The smartest course of action, Zhang said, is taking only the minimum dose required.

This conclusion came from the second review the team conducted. Working with two other authors, the team looked at data from 22 trials in which children were treated with low or medium doses of inhaled corticosteroids. Although only three of the trials followed children for a year or more, further owing to the problem’s poor recognition, the team found that lowering doses by one puff per day tended to boost growth rates by a quarter of a centimeter per year.

Together, the findings imply a sweet spot doctors and users can strike where both breathing complications and growth rate can be accommodated. What the reviews can’t discern is which drugs did the heavy lifting, since the analyses didn’t try to achieve that data directly. Further research into which drugs do the most damage is still needed, the team argues.

In the meantime, Ducharme says, "we recommend that the minimal effective dose be used in children with asthma…Growth should be carefully documented in all children treated with inhaled corticosteroids, as well in all future trials testing inhaled corticosteroids in children."

Source: Zhang L, Prietsch SOM, Ducharme FM. Inhaled corticosteroids in children with persistent asthma: effects on growth. Cochrane Database of Systematic Reviews. 2014.