Whether fibromyalgia syndrome (FMS) can be classified as a somatoform disorder is under debate.
Literature searches on the classification of FMS as a somatoform disorder were performed in Medline and in evidence-based guideline databases.
A somatoform disorder is defined by medically unexplained somatic symptoms that persist for at least 6 months and lead to a significant impairment of the ability to function in everyday life. The nature and extent of the symptoms or the distress and pre-occupation of the patient cannot be explained fully by a general medical condition or by the direct effect of a substance, and are not attributable to another mental disorder. Emotional and psychosocial conflicts play a major role in the onset, severity, exacerbation or maintenance of the physical symptoms. There is disagreement in the FMS research community on the existence of somatic factors sufficiently explaining FMS symptoms. Psychosocial factors play a major role in the onset, exacerbation or maintenance of FMS symptoms in the majority of patients. A biopsychosocial model of interacting biological and psychosocial factors in the predisposition, onset and maintenance of FMS symptoms is more appropriate than the dichotomy between a somatic disease and a mental (somatoform) disorder.
The clinical features of FMS and persistent somatoform pain disorder or somatization disorder according to the International Classification of Diseases (ICD)-10 overlap in individuals with chronic widespread pain without specific somatic disease factors. FMS is not synonymous with somatoform disorder.