Health A-Z


Chronic fatigue syndrome

Chronic fatigue syndrome (CFS) is a complex illness that affects many systems of the body, particularly the nervous and immune systems. People with CFS experience extreme tiredness that doesn't go away with rest and cannot be explained by other more easily detected causes.

The effects of CFS vary widely. Some people continue to function at a reduced level; others are severely disabled and cannot perform many routine activities. When severe, it can have a major impact on all areas of life including work, recreation, social and family life.

With an estimated 20,000 sufferers in New Zealand, CFS affects more people than breast cancer or multiple sclerosis. It is classified by the World Health Organisation as a neurological disorder.

Chronic fatigue syndrome (CFS) is also known as:

  • myalgic encephalomyelitis (ME)
  • post-viral fatigue syndrome (PVS)
  • chronic fatigue immune dysfunction syndrome (CFIDS)
  • Tapanui flu.

For simplicity, in this article we refer to the condition as CFS.


It is likely that a number of factors contribute to the development of CFS, including genetic predisposition.

For many people, CFS begins after an acute infection such as flu, bronchitis, hepatitis or an intestinal bug; for some it may follow a bout of glandular fever. In others it appears to develop gradually with no clear precipitating event.

CFS can affect people of all ages, ethnic and socio-economic groups. It affects more women than men. 


People with CFS experience overwhelming physical and mental tiredness (fatigue). This is different to the tiredness that well people experience after strenuous exercise or a day's work. It also differs from the ongoing (chronic) fatigue associated with many long term illnesses. CFS-associated fatigue can be debilitating and does not readily get better with rest.

Other common symptoms include:

  • impaired memory or concentration
  • sore throat
  • tender lymph nodes
  • muscle pain
  • multiple joint pain without joint swelling or redness
  • headaches of a new type, pattern or severity
  • unrefreshing sleep
  • tiredness that lasts more than 24 hours after physical or mental exertion.

Some people also report a range of other symptoms such as nausea, loss of appetite, irritable bowel syndrome, bloating, diarrhoea, irregular heartbeat, chest pain, jaw pain, night sweats, increased sensitivity to alcohol or other medications, chronic cough, dizzy spells or dry eyes.

All symptoms can worsen with excessive mental or physical exertion. This makes it distinct from depression; the symptoms of which tend to improve with exercise. 


Diagnosis can be difficult because the symptoms of CFS are similar to those of a number of other medical conditions, which need to be excluded first. For a diagnosis of CFS the symptoms must match both of the following criteria:

  • severe chronic fatigue lasting six consecutive months or longer with other known medical conditions excluded by clinical diagnosis, and
  • four or more of the other symptoms listed above, which they have not experienced before onset of the fatigue.

Diagnostic criteria NICE Pathway (USA)
American criteria are slightly different – CFS Criteria Centre for Disease Control (USA)


Currently there is no proven effective treatment for CFS, however several drugs are being studied. The Associated New Zealand ME Society (ANZMES) warns people with CFS to approach with caution any unproven treatments that carry claims of a cure.

Some prescription and over-the-counter medications may relieve specific CFS symptoms, such as

  • sleep problems
  • pain
  • gastrointestinal difficulties
  • allergies
  • depression.

People with CFS may have unusual responses to medications, so extremely low dosages should be tried first and gradually increased as appropriate, with medical advice. Lifestyle changes are also often recommended. These may include:

  • increased rest
  • reduced stress
  • dietary restrictions
  • nutritional supplementation
  • minimal aerobic exercise.


The course of this illness varies widely; many people improve over time (over months and years rather than weeks) and some recover well. The important thing to remember is that this is not a progressive or life threatening disease. However remissions and relapses are common and many people remain severely affected. It is estimated that less than 10% of people with CMS regain their previous level of health.

Early diagnosis and treatment may lessen the severity of the illness and, with careful management, full recovery is possible.

Learn more

What is ME (CFS)? The Associated NZ ME Society (NZ)
Chronic fatigue syndrome International Society for Chronic Fatigue Syndrome and ME

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Source: Health Navigator