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How the Placebo Effect Works

Prescribing Placebos

Although doctors have been prescribing placebos for ages, they haven't talked about it very much. Only recently have researchers began to really study the clinical uses of placebos. The first survey of its kind was conducted by a medical student and a physician at the University of Chicago in late 2007. It showed that 45 percent of the about 200 doctors in Chicago-area hospitals had prescribed a placebo at some point in their medical practice. Nearly all the doctors believed that placebos had a therapeutic effect, even those who hadn't prescribed them [source: Sherman]. Another study conducted in October 2008 showed similar results. Half of the more than 600 doctors across the United States that responded to the survey said that they had prescribed placebos [source: Tilbert].

Often, doctors prescribe placebos because they have no other form of relief to offer the patient. Either there is no effective medication available, or the patient can't take the commonly used medications due to side effects or other reasons. For example, if a patient complains repeatedly of a symptom like fatigue, but the doctor can find no underlying cause for it, he or she might suggest that the patient take vitamins. Dr. Danielle Ofri described this scenario when she was interviewed about the 2008 survey. She said "I'll explain vitamins have worked for some of my patients, and there's no downside" [source: CNN]. Vitamins can certainly have benefits for some people, but there's probably not any definitive proof that they'll cure a patient's fatigue.

Doctors sometimes prescribe a placebo because the patient insists on taking some type of medication. Although it might sometimes be a case of simply giving the patient what he or she wants, doctors who prescribe placebos for this reason are more likely to decide that giving the patient nothing would be more harmful. One common example is the prescription of antibiotics when a patient has a cold or other illness caused by a virus. Antibiotics are only effective in treating bacterial infections, not viral ones, but many patients believe that they need an antibiotic anyway. Some doctors who prescribe them in these situations argue that the patient may end up having a bacterial infection anyway due to their weakened immune system. However, this practice seems to be less common as we learn more about antibiotic-resistant bacteria and the need to prescribe antibiotics only when absolutely necessary.

When a doctor prescribes a placebo, it's not usually a sugar pill. According to the surveys, the two most commonly prescribed placebos were over-the-counter pain pills like aspirin and vitamins. Other doctors have prescribed antibiotics or sedatives. Critics argue that none of these are true placebos because they all contain ingredients that are active in some way, even if they aren't known to work for the patient's particular condition.

Of course any use of a placebo is controversial. Next, let's look at some of the criticisms and ethical concerns associated with placebo prescription.