[Placebo effect in the treatment of pain].

The placebo induces a significant analgesia on average in 35% patients with some variations according to the studied pathology and the modalities of the therapy. This placebo effect is especially influenced by the expectations and beliefs of the patient, the doctor, the environment and the quality of the doctor-patient relationship. As with a real psychogenic analgesia, this effect could partly result in a release of endogenous opioid substances. By a good relationship with his patient and a treatment corresponding to his expectations and his beliefs, the doctor induces a powerful placebo effect which increases the specific effects of his analgesic treatment.