The placebo effect has been recognized for years. It’s defined as a medical intervention not expected to have an effect through a known physiological mechanism. Despite this lack of demonstrated benefit, patients who receive a sham treatment frequently report it helped them.

Recently, a survey of two-hundred-thirty-one physicians at Chicago medical schools indicated a surprisingly large use of placebos. Nearly half said they had prescribed placebos for patients, with twenty-three percent saying they had done so in the past year. This didn’t include treatments that were part of studies of new drugs, which often use sham treatments for comparison.

Survey respondents had prescribed products such as vitamins or ibuprofen for complaints they knew weren’t likely to be addressed by the treatment. The most commonly prescribed placebos, though, were antibiotics for viral or other non-bacterial conditions against which these drugs have no effect.

Reasons cited by the physicians for giving the placebos were to calm patients or to provide a supplemental treatment. Others said they acted to keep patients from complaining or to answer what the doctors considered unjustified demands for medication.

These latter reasons don’t meet American Medical Association guidelines, which say that placebos shouldn’t be used in a way that serves the physician’s convenience more than it promotes the patient’s welfare. The A-M-A also says a placebo should be used only if the patient is informed and agrees to its use.

In other words, what you don’t know may help you, but you should know about it anyway.