Placebo Response and Placebo Effect: What Is the Difference?

Placebo response is different from the placebo effect. Whereas the placebo response is the global response to a placebo, including spontaneous remission, regression to the mean, patients' and experimenters' biases, as well as psychological factors, the placebo effect includes only the psychological factors, such as patients' expectations and learning. It is like the difference between drug response and drug effect, whereas the former is the global response to a drug, the latter represents the specific pharmacodynamic effect. Nocebo responses and nocebo effects go in the opposite direction; these consist in the experience of adverse events when a placebo is administered.