Placebo

Background. The placebo reaction is a widely known phenomenon but the way i t develops is not fully understood. This fact has given rise to numerous mi sinformed opinions on this subject. Placebo analgesia. More research has been done in the field of placebo anal gesia, where the involvement of the endogenous opioid systems was discovere d some twenty years ago. Recently there have been some new discoveries conc erning the role of expectancy and drug conditioning in experimentally induc ed placebo analgesia. Placebo reaction. The placebo reaction is very impressive not only followin g drug administration, but also after surgical operations. In many cases, i t is extremly difficult to decide whether a therapeutic success is due to a given medical intervention or to a placebo response. The use of placebo co ntrolled clinical studies remains an ethically charged issue.