Placebo effect and placebos: what are we talking about? Some conceptual and historical considerations.

Placebos and the placebo effect have always been present in medical history. However, they have not received the same consideration over the years. Somewhere between art and science, the placebo historical references come from Ancient Egypt and cross over the major civilisations, beliefs and scientific advances. The use of placebo as a methodological tool has assumed a leading role in the last 50 years and has become an important role in controlled clinical trials, the main element of the "evidence-based-medicine" paradigm. Knowledge of the conceptual and historical considerations of placebo may help to understand its role in medical practice. Even without a consensual definition, and assuming that the placebo effect does not seem to be fully dependent on a placebo administration, one issue seems unquestionable: the placebo effect is present in clinical practice and in clinical trials, no matter which name we choose to call it.