Worldwide fatigue is the most common symptom that is presented to a health practitioner. There are different levels of fatigue which are given different labels. The precise cause of fatigue in any one individual is rarely able to be determined therefore the terms used are often interchangeable.

Fatigue is a symptom, not a condition

Symptoms can be grouped into four categories.

  1. Acute fatigue
  2. Persistent fatigue
  3. Chronic fatigue syndrome  ( new term being considered this and ME/CFS is systemic exertion intolerance disease  SEID)
  4. ME/CFS or M.E. (Myalgic Encephalomyelitis) – This is the term used in the UK

Chronic fatigue syndrome is often over diagnosed as many conditions have fatigue as part of the disease diagnosis. For example, active rheumatoid arthritis is associated with a persisting fatigue state and once the illness is effectively treated fatigue resolves. This is an example of chronic fatigue and not chronic fatigue syndrome (CFS)  or ME/CFS. The latter is a “disease state” and as yet there are no certain causes or predicable and easily identified biomarkers.


Acute fatigue  –  Persistent fatigue

Fatigue can be associated with many conditions and there can be multiple contributing factors.


Age and gender
Thyroid or other metabolic /endocrine disorders
Cardiac and or respiratory conditions
Sleep disorder( organic)


Post-traumatic stress disorder
Sleep disorder (non-organic)


Family and relationship problems
Occupational stress


Drug and alcohol abuse
Sleep deprivation
Sedentary lifestyle
Inappropriate diet

In coming to a diagnosis it is important that a thorough evaluation is undertaken to identify and exclude treatable conditions that cause fatigue.

Chronic Fatigue Syndrome (CFS)

  1. CFS is a diagnosis of exclusion of other diseases
  2. Clinically characterised by severe and disabling new-onset fatigue with at least four additional symptoms: impaired memory or concentration, sore throat, tender cervical or axillary lymph nodes, muscle pain, multi-joint pain, new headaches, unrefreshing sleep or post-exertion malaise.
  3. It is a neuro-immune-endocrine dysfunction. Central sensitisation is the most likely common pathophysiological substrate for this, and other fatigue -like syndromes.

Up until recently a psychologically based model  was widely held to be the basis for the aetiology of fatigue associated syndromes.  However research is uncovering molecular, neurological, endocrine and immunological deficits in many patients leading to the potential for biologically based therapeutic interventions.