What Is the Placebo Effect?
How Does the Placebo Effect Work? continued...
The same appears to be true for negative effects. If people expect to have side effects such as headaches, nausea, or drowsiness, there is a greater chance of those reactions happening.
The fact that the placebo effect is tied to expectations doesn't make it imaginary or fake. Some studies show that there are actual physical changes that occur with the placebo effect. For instance, some studies have documented an increase in the body's production of endorphins, one of the body's natural pain relievers.
One problem with the placebo effect is that it can be difficult to distinguish from the actual effects of a real drug during a study. Finding ways to distinguish between the placebo effect and the effect of treatment can improve and lower the cost of drug testing. And more study may also lead to ways to use the power of the placebo effect in treating disease.