People taking heartburn medications are more prone to C. difficile infections, which can cause severe diarrhea, researchers in Montreal have found.

Dr. Sandra Dial and her colleagues at McGill University studied data on more than 18,000 patients in Britain from 1994 to 2004. The researchers looked for people diagnosed with C. difficile and then checked to see if they were taking heartburn drugs.

Patients taking drugs such as Nexium and Losec showed triple the risk of being diagnosed with C. difficile than those not taking the drugs, Dial's team reports in Wednesday's issue of the Journal of the American Medical Association.

The risk of C. difficile-related diarrhea doubled for those taking anti-heartburn drugs such as Zantac, according to the study.

The research suggests stomach acid may help protect people from C. difficile infection by preventing the bacteria from colonizing. The drugs reduce stomach acid.

"We hypothesize if your stomach acidity was less, that maybe ... you'd be a bit more susceptible to develop the infection, if you were exposed," Dial said.

The database results also showed that more than 70 per cent of patients who developed C. difficile had not been admitted to hospital in the past year and less than half had taken antibiotics in the three months before the infection.

The results suggest C. difficile has left the hospital setting and has reached the community, said study author Dr. Samy Suissa, director of clinical epidemiology at the McGill University Health Centre.

It also shows antibiotics are not the only culprit as previously believed, Suisa added.

Dial said patients should not stop taking heartburn medications. Every drug carries risks and side effects and the chance of getting C. difficile remains very low. Patients on heartburn medications who are concerned should talk to their doctors, she advised.

One strain of C. difficile was blamed directly or indirectly for more than 200 deaths in hospitals in Quebec during the first six months of 2004.