Names of the illness

'Chronic Fatigue Syndrome' is the name adopted for the illness in 1988 by the medical research community. They prefer this name since it doesn't imply anything about the cause of the syndrome, while highlighting the principal symptom. 'Post-Viral Fatigue Syndrome' (or, more commonly in Australia, 'Post-Viral Syndrome') implies a viral cause or trigger, which is not always the case. 'Myalgic Encephalomyelitis' (ME) means myalgia (muscle pain) plus inflammation of the brain and nerves (encephalomyelitis). While myalgia is common in the syndrome, inflammation of the brain and nerves is rarely - if ever - present.

Chronic Fatigue Syndrome as a name for the illness is intensely disliked by people with CFS, since it trivialises the illness. It is equivalent to calling diabetes 'chronic thirst syndrome', or Parkinson's disease 'chronic shaking syndrome'. Although the name emphasises the main symptom, it does not convey the potential severity of the illness or the distress that other prominent associated symptoms can cause.

In the United Kingdom and Canada, patient self-help groups retain the name Myalgic Encephalomyelitis, while in the United States, 'Chronic Fatigue and Immune Dysfunction Syndrome' (CFIDS) is common.