People on popular prescription heartburn drugs Prilosec, Prevacid and Nexium seem more prone to getting a potentially dangerous diarrhea caused by the bug Clostridium difficile, new research shows. C-diff, as it’s known, can cause severe diarrhea and crampy intestinal inflammation called colitis.

Dr. Sandra Dial and colleagues at McGill University in Montreal examined data on more than 18,000 patients in the United Kingdom from 1994 to 2004. During that time, 1,672 cases of C-diff were diagnosed, and the numbers increased from less than one per 100,000 in 1994 to 22 per 100,000 last year.

Patients with prescriptions for powerful acid-fighters called proton pump inhibitors, which include Prilosec and Prevacid, were almost three times more likely to be diagnosed with the bug than those not taking the drugs.

Those on less potent prescription drugs called H2 receptor antagonists, which include Pepcid and Zantac, were two times more likely than non-users to get C-diff infections.

The widely used and heavily promoted drugs reduce levels of gastric acid that can keep C-diff germs at bay.

Dr. L. Clifford McDonald, a researcher at the federal centers for Disease Control and Prevention, said proton pump inhibitors recently were implicated in a C-diff outbreak at a hospital and nursing homes in Maine.

"It’s not surprising in my mind that there could be some association with acid-fighting drugs," said Dr. McDonald, who was not involved in Dial’s study. If there is, "I do think it would be very important because, everyone and their brother seems to be on them.’’

Most study patients hadn’t been recently hospitalized and weren’t taking antibiotics, which both can increase risks for C-difficile infections.

Also, most patients hadn’t been diagnosed with ulcers or acid reflux, so it’s possible many simply had heartburn, Dr. Dial said.

"Heartburn in and of itself isn’t dangerous, and can often be treated with less potent drugs," Dr. Dial said.

Her study appears in the Journal of the American Medical Association.

A co-author is a consultant for AstraZeneca PLC, which markets Prilosec and Nexium, and Altana Pharma, which makes and markets another prescription heartburn drug, Protonix, in Europe.

AstraZeneca spokeswoman Cindy Callaghan said patient safety is the company’s top priority and that the findings are not the final word.

"Further research is needed in this particular area to determine the validity of a potential link,’’ she said.

Doctors think the growing trend is due in part to overuse of antibiotics but the new data suggest overuse of acid-fighting drugs may be another reason, said Dr. Michael Brown, a gastroenterologist at Rush University Medical Center in Chicago, who was not involved in the study.

The drugs are popular because they are so effective at fighting stomach acid, and are generally very safe, Brown said.

Brown said short-term use of potent acid-fighting drugs for occasional over-imbibing is unlikely to increase infection risks in otherwise healthy people.