How the Placebo Effect Works | HowStuffWorks

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The placebo effect

The placebo effect happens when a person takes medication that he thinks will help, but the medication has not been proven to be effective for the specific condition.

Placebos work in about 30 percent of patients. Some placebos contain no active ingredient. Other placebos do have active ingredients but aren't proven to work on the patient's particular condition. There are even placebos in the form of surgery, injections, and other types of medical therapies.

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The subject-expectancy effect

When people know what the result of taking a pill is supposed to be, they might unconsciously change their reaction to cause that result or report that result has taken place even if it hasn't.

However, studies show that a placebo doesn't trick the brain - the brain reacts differently to a drug than a placebo. A 2004 study showed that the expectation of pain relief causes the brain's relief system to activate.

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Placebos in research

Placebos are often used in clinical drug trials to determine how well a potential medicine will work.

There are two different groups of subjects in a placebo-controlled trial - one receives the experimental drug and the other the placebo. Neither researchers nor subjects know which group is receiving the real drug or the placebo.
Some researchers are questioning the placebo-controlled trial. Not everyone thinks a drug is ineffective if the placebo performs better.
Other critics of the placebo-controlled trial state it's wrong to attribute all positive outcomes to the placebo because many illnesses can resolve without any treatment.
When a patient takes a placebo and experiences adverse side effects, it's called a nocebo effect. Patients taking active drugs have also been known to have side effects that can't be directly attributed to the drug.

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Prescribing placebos

A 2007 study revealed that 45 percent of doctors had prescribed a placebo at some point. Doctors believed that placebos had a therapeutic effect.

The most commonly prescribed placebos are aspirin, vitamins, and antibiotics. Doctors prescribe placebos because they have no other form of relief to offer the patient. Other times, the patient insists on taking some type of medication.

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The placebo prescribing controversy

The American Medical Association created a policy concerning placebos that states that "physicians may use placebos for diagnosis or treatment only if the patient is informed of and agrees to its use."

Generally, doctors who prescribe placebos say that they have something they believe may help, but they don't know exactly how it will work. They don't believe they are lying to the patient, because the patient could still benefit from the placebo effect.
Another problem in prescribing placebos is that they have been shown to only work on half the population. The placebo effect is also short-term - it doesn't work for chronic conditions.
Prescribing drugs such as sedatives and antibiotics as placebos could do more harm than good. Many sedatives are habit-forming, and prescribing antibiotics may contribute to the rise of antibiotic-resistant bacteria.

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