TORONTO -- A new study suggests getting a flu shot doesn't exacerbate inflammatory bowel disease in children and teens and may even protect them from flare-ups.

Children who suffer from inflammatory bowel disease are encouraged to get flu shots every year, because the drugs they take weaken their ability to fend off infections.

But some of these patients are worried about getting the shots because there have been reports the flu vaccine can cause their disease to flare.

So several Ottawa researchers did a study to see if that was true; their work is in this week's issue of the journal Pediatrics.

Lead author Dr. Eric Benchimol says the findings show that getting a flu shot doesn't lead to flare-ups in these patients.

Children with inflammatory bowel disease cannot use the inhaled flu vaccine, which contains live but weakened viruses; they can only get the shot, which contains killed flu viruses.

Inflammatory bowel disease is an umbrella term for conditions of the small intestines and colon such as Crohn's disease and ulcerative colitis.

Benchimol, a pediatric gastroenterologist from the Children's Hospital of Eastern Ontario, says Canada has among the world's highest rates of inflammatory bowel disease in both children and adults, with about one in 200 Canadians affected. Rates appear to be climbing sharply among kids under the age of 15.

The reason for the high rates isn't known, though it is suspected some environmental factor may be at play.

Using administrative data for Ontario, Benchimol and his co-authors looked at records for all children under the age of 19 with inflammatory bowel disease between 1999 and 2009.

They did several analyses, comparing their rates of hospital or outpatient visits during flu seasons when they got a shot to those when they didn't. They also compared them to children who were like them in age, gender and other characteristics, but who didn't have inflammatory bowel disease.

Only about a third of the inflammatory bowel group got flu shots, though fewer of the other children did.

The researchers saw no real increase in health-care use after the inflammatory bowel patients got flu shots. And they appeared to use health care less in the years when they got a flu shot, suggesting the vaccine might have been protective, Benchimol says.

That would make sense, he explains. Often when these patients contract infections -- stomach bugs or colds or flu -- they will experience an episode of disease activity.

"Everybody in the house gets it and everyone else gets better but the IBD patient kind of flares up and starts having blood in their stool and other symptoms," he says.

He says the authors hope these results will persuade the parents of children with inflammatory bowel disease that these kids should get a flu shot every year.