From a historical perspective, the first data related to the placebo effect on “mental health” date to the 1950s decade, when evidence was first shown of the important percentage of people with a psychiatric pathology that benefited from the consumption of placebos. It is believed that the responses to placebos and nocebos are influenced by the content and the way of informing the patient, which influences in the quality of life and therapy adherence. Among the factors that influence the magnitude of the placebo effect, we find variables related to the patient, with the placebo itself and the therapist.

To determine the relationship between the clinical response of a placebo and the behavior and information on the placebo contributed by the health worker.

Systemic review of the articles published in Medline-PubMed from 2005 to the present.

Being kind, friendly, interested, nice, emphatic, and considerate as well as having a positive attitude toward the patient and the treatment as well as the expectations of the therapist are variables that are associated to a beneficial effect in a placebo situation as well as in active treatment.

The patient's expectations, a product of selective processing of the information that she/he receives about the effect of a placebo or active treatment, and the behavior of the health worker in clinical practice, produces variability in the symptomatic response through its influence on the magnitude of the placebo effect. In the bibliography reviewed, there is a marked lack of attention dedicated to clinical studies in the addressing of this phenomenon.

The authors have not supplied their declaration of competing interest.