• Chronic, widespread noninflammatory musculoskeletal pain syndrome with multisystem manifestations. Although the specific pathophysiology has not been fully elucidated, it is generally thought to be a disorder of altered central pain regulation.
  • Synonym(s): FMS; fibrositis, fibromyositis (misnomers)



  • Predominant sex: female (70–90%) > male
  • Predominant age range: 20 to 65 years

2–5% of adult U.S. population (1); 8% of primary care patients

Etiology and Pathophysiology

  • Idiopathic; appears to be a primary disorder of central pain processing (central sensitization) with afferent augmentation of peripheral nociceptive stimuli
  • Alterations in neuroendocrine, neuromodulation, neurotransmitter, neurotransporter, biochemical, and neuroreceptor function/physiology
  • Sleep abnormalities—α-wave intrusion
  • Systemic inflammation is not a feature of fibromyalgia, although localized immunologic processes in the CNS may play a role.


  • Genetics
    • High familial aggregation
    • Inheritance is unknown but likely polygenic.
    • Odds ratio may be as high as 8.5 for a first-degree relative of a familial proband.
  • Environmental—several triggers have been described:
    • Physical trauma or severe illness
    • Stressors (e.g., work, family, life events, and physical or sexual abuse)
    • Viral and bacterial infections

Risk Factors

  • Female gender
  • Poor functional status
  • Negative/stressful life events
  • Low socioeconomic status

General Prevention

No known strategies for prevention

Commonly Associated Conditions

  • Often a comorbid condition with other rheumatologic or neurologic disorders
  • Obesity is common and associated with increased severity of symptoms.

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