Chronic fatigue syndrome is a flu-like condition that can drain your energy and sometimes last for years. People previously healthy and full of energy may experience a variety of signs and symptoms.
People with chronic fatigue syndrome exhibit signs and symptoms similar to those of the most common viral infections. Unlike flu (influenza) symptoms, which usually subside in a few days or weeks, the signs and symptoms of CFS can last much longer. They may come and go frequently with no identifiable pattern.
In addition to persistent fatigue not caused by other known medical conditions, chronic fatigue syndrome has eight possible primary signs and symptoms.
According to the International Chronic Fatigue Syndrome Study Group — a group of scientists, researchers, and doctors brought together by the Centers for Disease Control and Prevention (CDC) to determine a standard method for defining and diagnosing chronic fatigue syndrome — a person meets the diagnostic criteria of chronic fatigue syndrome when unexplained persistent fatigue occurs for six months or more along with at least four of the eight primary signs and symptoms.
In addition, people with Chronic Fatigue Syndrome have reported other various signs and symptoms that aren't part of the official definition.