(Reuters Health) - Children treated for respiratory illnesses in the emergency department often have a chronic cough that lingers for weeks after they go home from the hospital, an Australian study suggests.

Researchers examined data on 839 children treated for acute respiratory illnesses and found roughly three in four kids had a cough one week later. And after 28 days, one in four children had a chronic cough.

“Parents should seek advice if children have a cough lasting more than four weeks that is not getting any better, particularly if it is a wet cough (moist or gurgly sounding cough),” lead study author Dr. Kerry-Ann O’Grady of the Queensland University of Technology in Australia said by email.

There are many causes of chronic cough in kids, but the most common culprit is lung disorders, said senior study author Dr. Anne Chang, also of Queensland University of Technology.

“In most children in the study, the cause of the chronic cough was an underlying lung infection that is easily treated with antibiotics, a condition called protracted bacterial bronchitis,” Chang said by email. “However, most children with cough do not need antibiotics.”

All of the kids in the study were seen at a pediatric emergency department in Brisbane, Australia.

Half were at least 2.3 years old, although they ranged in age from less than one month to almost 15 years.

The children were followed weekly during the study and examined by a pediatric lung specialist after 28 days.

Among the 171 children who still had a cough at the end of the study, 59, or 35 percent, had a wet cough, while 45, or 26 percent, had a dry cough, researchers report in the Archives of Disease in Childhood. (In the rest, the cough was either variable, or the data were missing.)

Pulmonologists identified a new and serious chronic lung disease in 36 children, and 55 had protracted bacterial bronchitis.

The study wasn’t a controlled experiment designed to prove whether or how an acute respiratory infection might lead to a chronic cough or a lung disorder. It’s also possible that at least some of the kids had a lung condition prior to their initial visit to the emergency department with a respiratory illness.

However, chronic cough is a common health problem for kids that is usually treatable and can cause serious complications if it’s not properly diagnosed and treated, said Dr. Andre Schultz, a pulmonologist at Princess Margaret Hospital for Children in Perth, Australia, who wasn’t involved in the study.

“Chronic cough that is left untreated can result in permanent lung damage,” Schultz said by email.

Bacterial infections, for example, can cause progressive damage to the lungs and eventually permanent scarring if children don’t receive proper treatment,” Schultz said. This type of infection is often the culprit of chronic wet coughs when kids don’t have asthma.

“Respiratory infections could also be an indication of an underlying lung disease not yet diagnosed,” said Dr. Lilly Verhagen, a researcher at Wilhelmina Children’s Hospital in Utrecht, The Netherlands, who wasn’t involved in the study.

Because the study only included kids treated in the emergency department for respiratory problems, the results might not be the same for all kids treated by primary care providers, Verhagen, said by email.

But parents should still be aware that a chronic cough needs to be checked out, Verhagen said.

“If a child has a persistent cough lasting at least four weeks after a respiratory infection that was severe enough to require a hospital visit, parents should return for physician review and consideration of underlying lung disease,” Verhagen advised.

SOURCE: bit.ly/2vFZDP6 Archives of Disease in Childhood, online August 16, 2017.