[Fibromyalgia syndrome-Is the designation as a disorder of women a misinterpretation?]

Fibromyalgia syndrome (FMS) is a chronic pain condition accompanied by further characteristic key symptoms, such as sleep disturbance and fatigue. According to the literature it is often reported to be more frequent in women but the true sex-specific prevalence remains uncertain and potential underlying mechanisms are unknown.

To determine the prevalence of FMS in women and men and assess whether the clinical phenotype differs; if so, to consider possible contributing factors.

We conducted a literature search in PubMed from 1 February 1990 to 30 September 2025. Eligibility for inclusion in our systematic review was assessed by applying predefined inclusion and exclusion criteria during screening of titles and abstracts.

The search yielded 532 articles, of which 59 were included in the systematic review and among these were 5 animal experimental studies. Men with FMS were examined in 2/54 (3.7%) studies and direct sex comparisons were reported in 15/54 (27.7%). Under these conditions, the reported prevalence of FMS averaged 2.4-6.8% in women and 0.2-2.4% in men. The clinical phenotype was assessed across sexes in 7/54 (13%) studies; additionally, 2/54 (3.7%) cross-sectional studies included only women and 2/54 (3.7%) prospective cross-sectional studies included only men.

Current evidence suggests a higher FMS prevalence in women; however, most studies predominantly examined women, direct comparisons are scarce and no studies have investigated pathophysiological sex differences. Future research should address these knowledge gaps.