[Idiopathic environmental intolerance (IPI)--formerly multiple chemical sensitivity (MCS)--from the psychiatric perspective].

The term "idiopathic environmental intolerances" (IEI)/"multiple chemical sensitivities" (MCS) is used to describe a complex of heterogeneous somatic symptoms without a diagnosable organic disease. Symptoms are believed to be triggered by exposure to low levels of environmental chemicals that are usually well tolerated by the general population. There is no widely accepted definition for the phenomenon. A number of contradictory etiologic hypotheses and therapeutic concepts are discussed. One of the crucial questions is whether IEI/MCS should be understood as an own entity of disease. It has been demonstrated that a majority of patients with IEI/MCS meet diagnostic criteria for psychiatric diseases. Most frequently, somatoform, affective and anxiety disorders can be diagnosed. Therefore, psychiatric and psychotherapeutic therapy seems appropriate. The present paper provides a review of the different case definitions, etiologic and therapeutic concepts and of studies examining the frequency of psychiatric morbidity in patients with IEI/MCS. Additionally, a diagnostic algorithm and a concept of behavioral therapy for IEI/MCS patients with somatoform disorders are described.