Chronic Fatigue
Chronic fatigue that meets specific criteria for at least 6 months may represent myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), diagnosed per the 2015 Institute of Medicine (now National Academy of Medicine) criteria, adopted by the CDC.
Symptoms
Substantially reduced ability to engage in pre-illness activities, unrefreshing fatigue lasting more than 6 months, post-exertional malaise (a worsening of symptoms after physical or mental exertion), and unrefreshing sleep, plus either cognitive impairment or orthostatic intolerance.
Causes and risk
The exact cause is not fully understood; ME/CFS often follows an infection (including COVID-19), and immune, autonomic nervous system, and energy-metabolism abnormalities have all been described in research.
How it is evaluated
ME/CFS is a clinical diagnosis made after excluding other treatable causes of fatigue -- thyroid disease, anemia, sleep apnea, depression, and autoimmune disease should all be ruled out first.
Treatment
Pacing -- managing activity within one's energy envelope to avoid triggering post-exertional malaise -- is the cornerstone of management. Graded exercise therapy is now considered potentially harmful and is no longer recommended, per current ME/CFS guidance; CBT can be supportive but is not curative.
When to seek care
Fatigue accompanied by chest pain, shortness of breath, fainting, or significant unintended weight loss warrants prompt medical evaluation to rule out a more acute underlying cause.