[The placebo as a nonspecific treatment factor].

Nonspecific drug actions result from the social interaction between physician and patient and the medical environment. Positive (therapeutic) placebo effects are produced in approximately 30-35% of treated patients, especially in cases of vegetative and psychic disturbances. There appears to be no distinct group of individuals with specific personality features that can be classified as "placebo responders". Negative (toxic) placebo effects, which are usually minor, are reported in 4-50% of treated patients. The occurrence of side effects may cause the patient to assume treatment with an active agent, thus increasing the therapeutic efficiency of the treatment (placebo amplification by side effects). On the other hand, the lack of a certain side effect may diminish the therapeutic effect of an active drug. The notion that placebo-induced analgesia is endorphin-mediated is not established. Hence at present psychological mechanisms have to be assumed for the placebo effect. The conscious use of a placebo as a therapeutic agent is problematic for ethical reasons, whereas the placebo component of drugs with specific actions should be exploited to enhance their therapeutic efficiency.