Chronic fatigue syndrome (CFS), also called myalgic encephalomyelitis, is a complex long-term medical condition which often stops people from working or leading a normal life.
The disease is not fully understood.[1] Diagnosis is based on the person's symptoms, which usually include pain, because there is no agreed diagnostic test.[2] There is no agreed definition, but it may affect as many as 1% of the population in some places.[3]