Background: The classification and etiology of medically unexplained symptoms remain a clinical challenge. Recent proposals to improve systems of classification include ending the tradition of separating symptoms into medical or psychiatric groups.
Method: Several research questions are proposed to resolve some of the divergent opinions about the nature of these difficulties.
Conclusion: Unitary models of somatic symptom causation should not be presumed. Examination of the causes and nature of somatic distress in those with and without psychiatric disorders requires separate investigation for each, and these should not be presumed to be similar. Psychophysiological models of somatic symptoms are required that can be studied in research protocols.