Forty-five percent of Chicago internists report they have used a placebo at some time during their clinical practice, according to a study in the January issue of the Journal of General Internal Medicine.

"Placebos have been used in medicine since ancient times and remain both clinically relevant and philosophically interesting," said study author Rachel Sherman, a fourth-year medical student at the University of Chicago's Pritzker School of Medicine, in a news release.

"In addition to their recognized use as controls in clinical trials, this study suggests that placebos themselves are viewed as therapeutic tools in medical practice."

For the study, researchers sent questionnaires inquiring about placebo use to 466 internists at the University of Chicago, Northwestern University and University of Illinois, Chicago. Fifty percent (231) of the physicians responded.

Of the respondents who reported using placebos in clinical practice, 34 percent introduced the placebos to the patient as "a substance that may help and will not hurt." Nineteen percent called it "medication" and 9 percent said, "It is medicine with no specific effect." Only four percent of the physicians explicitly said, "It is a placebo."

Additionally, 33 percent of physicians reported they told patients, "This may help you but I am not sure how it works."

Only 12 percent of respondents said that placebo use should be categorically prohibited. The authors said that in the broader ethics literature, the routine use of placebos is controversial.

The authors added that a growing number of physicians believe in mind-body connection, meaning what a person thinks can impact the health and well-being of the body. Ninety-six percent of physicians in the study believed placebos can have therapeutic benefits.

The physicians most commonly defined a placebo as an intervention not expected to have an effect through a known or specific physiologic mechanism.