Fukuda et al developed criteria for diagnosing patients with the chronic fatigue syndrome. These can help distinguish the chronic fatigue syndrome from other overlapping conditions. The authors are from the International Chronic Fatigue Syndrome Study Group.

Prolonged fatigue is defined as persistent fatigue lasting >= 1 months.

Chronic fatigue is persistent or relapsing fatigue lasting >= 6 months.



(1) presence of clinically significant chronic fatigue of new or definite onset (not lifelong)

(2) presence of >= 4 symptoms concurrently for >= 6 months

(3) no other explanation or cause is found after a complete workup


Features of clinically significant fatigue:

(1) not a result of ongoing exertion

(2) not substantially relieved by rest

(3) causes a significant reduction from the previous level of activity (including occupation, education, social and/or personal)



(1) impaired memory and/or concentration

(2) sore throat

(3) tender cervical and/or axillary lymph nodes

(4) muscle pain

(5) pain in multiple joints

(6) new onset of headache

(7) unrefreshing sleep

(8) post-exertional malaise


If the patient does not meet all of the criteria for the chronic fatigue syndrome, then classify as idiopathic chronic fatigue.

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