The hallmark symptoms of Chronic Fatigue Syndrome are overwhelming fatigue and weakness that make it extremely difficult to perform routine and daily tasks, like getting out of bed, dressing, and eating.

Symptoms

The symptoms of CFS are so vague and can vary widely from person to person. The CDC developed a detailed case definition to help doctors diagnose it. According to that definition, in order to be diagnosed with CFS a person must have both:

1. severe, chronic fatigue for at least 6 months or longer that is not alleviated by rest, with other known medical conditions having been excluded by a doctor's diagnosis
2. four or more of the following symptoms:

1. forgetfulness or difficulty in concentrating
2. sore throat
3. tender lymph nodes in the neck or armpit
4. muscle pain or multi-joint pain without swelling
5. headaches of a new type, pattern, or severity
6. unrefreshing sleep and vague feelings of illness or depression after exerting oneself, lasting more than 24 hours following exertion
7. tiredness that lasts longer than 24 hours