Placebo effect describes the phenomenon where a person believes a drug will produce a certain effect, and then it does — even if the drug is incapable of producing said effect. A placebo is a “fake” drug that is given in studies to gauge the efficacy of the “real” drug being tested.  

The placebo effect demonstrates how the mind, expectations, beliefs, and past experiences can all influence the body’s response to stimuli. Scientists aren’t entirely sure how the placebo effect works. But they do recognize it as a valuable tool when studying new drugs.

Often, in clinical studies, a percentage of the participants are given a placebo. This is usually something like a sugar pill or a saline injection. The study participants are not aware if they are receiving the “real” treatment or the placebo. And sometimes, those who receive the placebo treatment still report positive changes from taking the treatment, simply because they expected to. 

What is the nocebo effect?

On the other side of the coin is the nocebo effect. With the placebo effect, a person may experience positive effects after interacting with a medication because they expect to. But the nocebo effect is the opposite. This is where someone experiences negative effects after a treatment because they expect to.