Glossary · Y học
Placebo
A placebo is an inactive substance or treatment that looks the same as, and is given the same way as, an active therapy being tested. The placebo effect is a beneficial health outcome resulting from a person's anticipation that an intervention will help.
NCCIH's definition puts the weight on the patient's anticipation, not on the pill itself. NCCIH adds that how a health care provider interacts with a patient may also bring about a positive response that is independent of any specific treatment.
Three research findings NCCIH highlights: one study identified a genetic marker that may predict whether someone will respond to a placebo; another supported the idea that placebo responses may occur outside of conscious awareness; and a third suggested that placebos MAY be helpful even if patients know they are receiving placebos.
NCCIH calls the randomized, placebo-controlled clinical trial the gold standard for testing interventions in people: volunteers are randomly assigned to a test group receiving the experimental intervention or a control group receiving a placebo. Comparing results from the two groups suggests whether changes in the test group result from the treatment or occur by chance.