In order to receive a diagnosis of chronic fatigue syndrome, a patient must satisfy two criteria:
1) Have severe chronic fatigue of six months or longer duration with other known medical conditions excluded by clinical diagnosis; and
2) concurrently have four or more of the following symptoms: substantial impairment in short-term memory or concentration; sore throat; tender lymph nodes; muscle pain; multi-joint pain without swelling or redness; headaches of a new type, pattern or severity; unrefreshing sleep; and post-exertional malaise lasting more than 24 hours. The symptoms must have persisted or recurred during six or more consecutive months of illness and must not have predated the fatigue.
