[The placebo effect in functional disorders].

Functional disorders are clinical entities corresponding to complaints mimicking diseases without a clearly identified organic substrate despite a rigorous history and clinical examination. Sometimes, complementary examinations are necessary to rule out an organic lesion that could explain the symptomatology. The notion of a diagnosis of exclusion is therefore very present. The physician must constantly re-evaluate the diagnosis of functional disorder in order not to «miss» a diagnosis with an organic cause.The treatment of these functional disorders is sometimes based on psychological treatment when a psychogenic dimension seems to be involved. This is not always the case. In such cases it is necessary to be able to consider a placebo approach with the hope that the placebo effect may improve the patient's condition. This article discusses the placebo effect in functional disorders without omitting to address ethical and philosophical considerations.