Chronic fatigue syndrome

Myalgic encephalomyelitis​/​chronic fatigue syndrome (ME/CFS) is a disabling chronic illness. People with ME/CFS experience profound fatigue that does not go away with rest, as well as problems with sleep and memory or concentration. The hallmark symptom is post-exertional malaise (PEM), a worsening of the illness that can start immediately or hours to days after even minor physical or mental activity. This "crash" can last from hours or days to several months. Further common symptoms include orthostatic intolerance—dizziness or faintness when upright—and pain.

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