• 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; 8% of primary care patients

Etiology and Pathophysiology

  • Current consensus is that fibromyalgia is a primary disorder of central pain processing (central sensitization) with increased sensitivity to multiple classes of painful sensation (nociceptive, nociplastic, and neuropathic)
  • 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 and inflammatory processes in the CNS may play a role. There may be a distinctive cytokine profile in patients with fibromyalgia.


  • 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
  • Psychiatric comorbidities, including depression, anxiety, and posttraumatic stress disorder (PTSD) occur in 2/3 of patients—similar to findings in other chronic pain conditions.
  • Obesity is common and associated with increased severity of symptoms.

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