Chronic fatigue syndrome

Last Review Date: April 1, 2018

What is it?

Extreme, debilitating exhaustion is the hallmark of chronic fatigue syndrome (CFS). Those who have CFS sleep poorly and awake unrefreshed. They frequently have headaches, muscle and joint pain, sore throats, and problems concentrating and remembering things. The intensity and type of symptoms can vary from day to day. On a “good day” symptoms may be mild and someone with CFS may be able to function at a near normal level, but on a ‘bad day’ they may be unable to get out of bed.

Once dismissed as ‘yuppie flu’ – a form of depression, stress and burnout in young, upper society white women – CFS is now known to exist worldwide in every age, race, and in both sexes. It is about 1.5 times more common in women than in men and appears to be most prevalent in the 20 to 40 year age range. It is estimated that as many as 500,000 people in the U.S. may have CFS. It appears that the incidence of new cases of chronic fatigue is declining in Australia.

The weariness, pain, and numerous other symptoms that are associated with chronic fatigue syndrome can frustrate both patient and physician. They often make the patient miserable, but they do not cause visible, measurable abnormalities. This has lead to lingering scepticism over the existence of CFS despite the fact that all major health organisations now recognise it as a distinct condition. Some doctors attribute the symptoms their patients have to depression or stress, or feel that they are simply symptoms of another, as of yet undiagnosed, disease or disorder. While it is true that some of those with CFS are depressed, many are not. The incidence of depression is about the same as with any other chronic illness.

There are a large number of diseases, disorders, and temporary conditions that can cause (or have as a symptom or side effect) short or long-term fatigue. These may include hypothyroidism, mononucleosis, psychological disorders, eating disorders, cancer, autoimmune disease, infections, drug or alcohol abuse, reactions to prescription medications, and – for whatever reason – not getting enough hours of uninterrupted sleep. In these cases there will be an underlying reason for the fatigue that can be established, and treated. This temporary, short-term, or long-term fatigue is not the same as CFS but it must be distinguished from it. Very few illnesses cause just fatigue.

The problem that researchers, doctors, and patients face in identifying and diagnosing CFS is that the cause of CFS is unknown. For many years, it was simply defined as an idiopathic chronic fatigue (fatigue of unknown origin). In the late 1980’s the US Centers for Disease Control and Prevention (CDC), in conjunction with an international panel of CFS research experts, adopted a definition of CFS (that was reviewed and updated in 1994).

According to this definition, a person with CFS needs to have:

  1. Severe chronic fatigue of six months or longer duration with other known medical conditions excluded by clinical diagnosis
  2. Concurrently have four or more of the following symptoms:
  • substantial impairment in short-term memory or concentration
  • sore throat
  • tender lymph nodes
  • muscle pain
  • multi-joint pain without swelling or redness
  • headaches of a new type, pattern or severity
  • unrefreshing sleep
  • post-exertional malaise lasting more than 24 hours.

These symptoms must have persisted or recurred during six or more consecutive months of illness and must not have predated the fatigue.

While this definition has been widely accepted and is used by researchers and physicians to both study and diagnose CFS, there is still no consensus as to the cause of CFS.

There are many researchers who believe that chronic fatigue syndrome is caused by or triggered by a viral infection, but no microorganism has been isolated as the instigator. Some still believe that an infection, trauma, stress, or allergy provokes a chronic immune reaction and that it is this immune reaction that causes CFS, though this is not widely accepted. Still others think that the central nervous system plays an important role and that hormone regulation is involved.

Some researchers think that CFS’s symptoms may be due to or exacerbated by depression, by neurally mediated hypotension (problems with blood pressure regulation), or due to disturbances that affect the quality and depth of sleep that an affected person gets. While the majority agrees that CFS is not contagious, the tendency to be predisposed may be inherited as family patterns of CFS have been observed. Some investigators feel that further research will reveal that CFS is not a single condition at all but a group of different disorders with a similar end point.

It is known that those affected by CFS have a definite start to their symptoms, a time before which they felt well and had the energy for normal daily tasks. About 75% of the time, CFS is preceded by what appears to be a flu-like illness. Other cases of CFS arise following a period of intense physical or emotional stress, and some emerge slowly with patients noticing a gradual decline in their energy and sense of well-being.

Signs and symptoms

Besides the primary symptoms of chronic fatigue syndrome, there are a variety of other symptoms that are commonly seen. These include:

  • Abdominal pain
  • Bloating
  • Chest pain
  • Chronic cough
  • Depression and anxiety
  • Diarrhoea
  • Dizziness
  • Dry eyes or mouth
  • Earaches
  • Irregular heartbeat
  • Jaw pain
  • Morning stiffness
  • Nausea and loss of appetite
  • Night sweats
  • Shortness of breath


At this time, there is no test that can be used to diagnose CFS. The syndrome is diagnosed by exclusion through:

  • Documenting the patient’s medical history
  • Performing a thorough medical examination
  • Conducting cognitive function tests
  • Ruling out other conditions that may be causing or exacerbating the fatigue (and/or identifying and treating those that can be treated)
  • Fulfilling the criteria for the CDC definition of CFS
  • Monitoring the patient over time to see if other underlying conditions arise

Laboratory tests can be useful to help diagnose conditions with similar symptoms and disorders that must be identified and treated before a diagnosis of CFS can be made. The CDC recommends a few general tests, listed in the next section.

Laboratory tests

Other tests may be ordered to follow up abnormal findings on the general tests and as warranted by a patient’s symptoms. These additional tests are used to help identify or rule out diseases and disorders that may be causing fatigue; they are not capable of directly diagnosing CFS.

These other tests may include:

  • ANA (antinuclear antibodies) ordered when an autoimmune disorder is suspected
  • TB skin test to check for exposure to the mycobacterium that causes tuberculosis
  • Lyme disease test when suspected and endemic in the patient’s geographical area. There is no proven evidence that Lyme disease can be acquired in Australia. In addition, the tick species present in Australia do not have the requisite life cycles to allow development of the Lyme disease causing bacterium.
  • Rheumatoid factor / CCP to determine whether rheumatoid arthritis may be present
  • HIV antibody test to check for HIV infection
  • Cortisol / ACTH when low cortisol concentrations and/or decreased adrenal gland function are suspected

Routine viral testing, such as for CMV (cytomegalovirus), EBV (Epstein Barr virus), herpes, enterovirus, adenovirus, and testing for candida albicans (yeast) is not diagnostic for CFS and is not recommended.

Other laboratory tests may be used in a research setting to attempt to better understand the cause and course of CFS but are not considered clinically useful at this time.

Non-laboratory tests
Occasionally, an MRI (magnetic resonance imaging) scan may be ordered to help rule out multiple sclerosis (MS) as a cause for a patient’s chronic fatigue. This would only be done when symptoms suggestive of MS are present. Other tests and imaging scans may be used in a research setting but are not considered clinically useful at this time.


Treatment of chronic fatigue syndrome focuses on symptom relief and lifestyle changes; there is currently no known cure. Many of those with CFS will get better over time, but some degree of illness may persist for years or for a lifetime. Experts recommend that patients track their energy levels and budget their time and activities. Eating well and getting regular amounts of moderate (but not excessive) exercise can help maintain functional abilities and improve a patient’s mood and ability to sleep. Support groups and counselling may help a patient deal with the physical, psychological, financial, and social frustrations their condition can cause.

Current strategies for relief of symptoms are targeted at improving the patient’s quality of sleep and relieving pain. Patients with CFS should work with their doctors to determine the best course of treatment for them. What works for one person may not work for another, and many with CFS are especially sensitive to medication side effects.

Related pages

On this site
Conditions: Fibromyalgia

Elsewhere on the web
HealthInsite: chronic fatigue syndrome
Medical Journal of Australia: chronic fatigue syndrome