For the study, Dial and her colleagues collected data on 1,672 cases of C. difficile infection recorded between 1994 and 2004 among patients registered in British medical practices.

They found that current use of proton pump inhibitors was linked with nearly three times the rate of CDAD, and the use of H2-receptor antagonists was associated with twice the rate of CDAD. In addition, the current use of pain relievers called nonsteroidal anti-inflammatory drugs (excluding aspirin) was associated with a 30 percent increased rate of C. difficile illness.

Dial believes that the suppression of stomach acid may increase the risk of CDAD. "Stomach acid is one of your protections against infections from ingested organisms," she pointed out.

The risk of developing CDAD is small, Dial said. "But when you consider the number of people taking these drugs, while the risk is small, they still increase your risk," she said.

According to Dial, the lesson from this study is that consumers have to be prudent when taking these common medications. "We have to be careful how we use drugs," she said. "Every drug has the potential to have side effects. If you're taking a drug, it's important to be on it for all the right reasons."