A survey of parents of 740 children with probable persistent asthma found just 49 percent knew what kind of medication their child was prescribed and how often to use it.
Following recommended guidelines is key to controlling asthma symptoms, experts say.
"Adherence to the guidelines has demonstrated improved outcomes: decreased hospitalisations, emergency department visits and outpatient visits," said study primary author Dr Ann Chen Wu, of the Harvard Pilgrim Health Care Institute in Boston.
Parents were asked which asthma controller medications their child was prescribed and how often they should be taken. Responses were compared to instructions from their child's health care provider.
Records showed that 77 percent of the children were supposed to use inhaled corticosteroids, 22 percent were to take leukotriene antagonists and 1 in 10 were to take a combination of inhaled corticosteroids and long-acting beta agonists such as Advair.
Communication needs to be improved
But deviations from the doctor's directions were common. For instance, nearly 30 percent of kids prescribed inhaled corticosteroids – an important preventive measure – weren't taking them as directed.
Children with severe asthma were not included in the study, which was published recently in the Journal of Allergy and Clinical Immunology.
Among roughly 200 children who were supposed to use the inhaled corticosteroids every day of the year, 27 percent of parents said otherwise. Among the 263 children who were supposed to use inhaled corticosteroids daily when asthma is active, more than half of parents said they weren't compliant.
"Of course, we need to improve provider-patient communication in the medical office, especially for controller medications for children with asthma, but providers may be unaware of their patient's lack of adherence," Wu said in a journal news release.
"A mismatch between parent and provider was more likely to happen if the parents felt that the medicine was not helping, or, conversely, if the parent believed their child did not need as much as prescribed," Wu added.
"Mismatches" were also more likely to occur among Hispanic parents, she and her colleagues said.