Rethinking the placebo effect.

There is a rather wide range of meanings for placebo and placebo effect, and some of the controversy has arisen when the proponents of various positions have ignored each other. An attempt is made to clarify some of the conceptual issues related to these concepts. Five uses of placebos as inert substances or treatments are listed. The problem of the placebo effect and the discussion of its existence are examined, and other terms that could cover the phenomenon are suggested. It is suggested that the concept placebo is appropriate only to the research context and that the term care effect be introduced to replace it in clinical contexts.