Also Known As
Chronic Fatigue and Immune Dysfunction Syndrome
Myalgic Encephalomyelitis (or encephalopathy)
Post-viral fatigue syndrome
This article was last reviewed on
This article waslast modified on 10 January 2020.
What is chronic fatigue syndrome?

Extreme, debilitating exhaustion is the hallmark of chronic fatigue syndrome (CFS). People with CFS sleep poorly and awake unrefreshed. They have frequent headaches, muscle and joint pain, recurring sore throats, and memory and concentration problems. The intensity and type of symptoms can vary from day to day and from person to person. On a "good day" symptoms may be mild, and someone with CFS may be able to function at a near normal level. On a "bad day," they may be unable to get out of bed. Their condition is not improved by bed rest and can be worsened by mental activity.

Once dismissed as "yuppie flu" – a form of depression, stress and burnout common in young, upper income white women – CFS is now known to exist worldwide in every age, income bracket, and ethnic group, and in both sexes. CFS is about four times more common in women than in men, but that may be because women are more likely to report their symptoms to a doctor and it appears to be most prevalent in the 40 to 60 year age range.

The weariness, pain, and numerous other symptoms associated with CFS can frustrate both patient and physician. Because they do not cause visible and/or measurable abnormalities, it can be hard for friends, family and the public to understand the painful challenges faced by a person with CFS. It has also led to lingering scepticism about the existence of CFS despite the fact that all major health organisations now recognise it as a distinct medical condition. Some doctors attribute their patients' symptoms to depression or stress, or believe that they are simply symptoms of another, as yet undiagnosed, disease or disorder. Depression is a common consequence of CFS, but it is not a cause.

A large number of other diseases, disorders, and temporary conditions can cause or display similar symptoms or side effects. These include hypothyroidism, mononucleosis, psychological disorders, eating disorders, cancer, autoimmune disease, infections, drug or alcohol abuse, reactions to prescription medications, and – for whatever reason – insufficient uninterrupted sleep. In these cases, an underlying reason for the fatigue can be established and often treated. This temporary, short-term, or long-term fatigue must be distinguished from CFS.


Accordion Title
About CFS
  • Signs and Symptoms

    The problem that researchers, doctors, and patients face in identifying and diagnosing CFS is that its cause is unknown and symptoms may be invisible and unmeasurable. For many years, CFS was simply defined as an idiopathic chronic fatigue (fatigue of unknown origin). NICE guidance states that healthcare professionals should consider the possibility of CFS if a person has:

    fatigue with all of the following features:

    • new or had a specific onset (that is, it is not lifelong)
    • persistent and/or recurrent
    • unexplained by other conditions
    • has resulted in a substantial reduction in activity level
    • characterised by post-exertional malaise and/or fatigue (typically delayed, for example by at least 24 hours, with slow recovery over several days)

    and one or more of the following symptoms

    • difficulty with sleeping such as insomnia, hypersomnia, unrefreshing sleep, a disturbed sleep-wake cycle
    • muscle and/or joint pain that is multi site and without evidence of inflammation
    • headaches
    • painful lymph nodes without pathological enlargement
    • sore throat
    • cognitive dysfunction, such as difficulty thinking, inability to concentrate, impairment of short term memory, and difficulties with word finding, planning/organising thoughts and information processing
    • physical or mental exertion makes symptoms worse
    • general malaise or ‘flu-like’ symptoms
    • dizziness and/or nausea
    • palpitations in the absence of identified cardiac pathology

    However, the symptoms of CFS fluctuate in severity and may change in nature over time.

    There is still no consensus as to a cause. While a single cause may yet be identified, many researchers believe that CFS has multiple triggers. These include:

    • Viral infection such as Epstein Barr virus, although no microorganism has been isolated as the instigator
    • Immune dysfunction provoked by trauma, stress, or allergy, which in turn triggers CFS
    • Nutritional deficiency
    • Abnormally low blood pressure (neurally mediated hypotension) that can cause fainting
    • Stress that activates the hypothalamus-pituitary axis (HPA) where the hypothalamus, pituitary and adrenal glands interact
    • Hormonal imbalance
    • Traumatic events e.g. Surgery, accidents

    While most researchers agree that CFS is not contagious, they have observed family patterns and believe there may be a tendency to an inherited predisposition to the condition. 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 onset of symptoms, that is, 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 those affected noticing a gradual decline in their energy and sense of well-being.

    Besides the primary symptoms of CFS, a variety of other symptoms are common. These include:

    • Abdominal pain
    • Allergies and sensitivities to foods, odours, chemicals, medication and sound
    • Bloating
    • Chest pain
    • Chills and night sweats
    • Chronic cough
    • Depression and anxiety
    • Irritable bowel or diarrhoea
    • Dry eyes or mouth
    • Earaches
    • Irregular heartbeat
    • Jaw pain
    • Low grade fever
    • Morning stiffness
    • Nausea and loss of appetite
    • Numbness, tingling or burning sensation in the face hands or feet
    • Shortness of breath

    There are three main types of CFS classified as mild, moderate and severe, which are defined by NICE according to how often and severely a person experiences symptoms and how living with CFS impacts them.

  • Tests

    At this time, there is no blood test, brain scan, or other test to diagnose CFS. It is diagnosed by exclusion through:

    • Documenting the patient's medical history
    • Performing a thorough medical examination
    • Ruling out other conditions that may be causing or exacerbating the fatigue
    • Fulfilling NICE criteria for the definition of CFS
    • Monitoring the patient over time to see if other underlying conditions arise

    Laboratory tests can be useful to help diagnose and manage other 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, bulleted in the next section.

    Laboratory tests

    The following tests should usually be done:

    Additional investigations may be necessary to exclude other diagnoses. Other laboratory tests may be used in a research setting to attempt to better understand the cause and course of CFS.


  • Management

    As there is currently no cure and there are no specific drugs developed for CFS, treatment focuses on symptom relief and lifestyle changes. These include:

    • Cognitive behavioural therapy and graded exercise at the clinical level
    • Sleep management techniques
    • Relaxation and stress-reduction techniques
    • Medication to reduce pain discomfort and fever
    • Medication to treat anxiety (anti-anxiety drugs)
    • Medications to treat depression (anti-depressant drugs)
    • Daily living aids
    • Graded exercise therapy and cognitive behavioural therapy at the clinical level
    • Structured exercise programmes
    • Complementary and alternative therapies-co-enzyme Q10, magnesium supplementation, herbal medicine, acupuncture, the Perrin osteopathic treatment, gentle yoga/meditation and acupuncture/acupressure
    • Pharmacological treatment: rintatolimod, rituximab and anakinra.

    Many people with CFS will get better over time, but some degree of illness may persist for years or for a lifetime. Medical experts recommend that those with CFS track their energy levels and budget their time and activities. Eating well and taking regular amounts of moderate (but not excessive) exercise can help maintain functional abilities and improve a person's mood and ability to sleep. Support groups and counselling can help a person deal with the physical, psychological, financial, and social frustrations caused by CFS.

    Current strategies for relief of symptoms are targeted at improving the person's quality of sleep and relieving pain. People 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.

    Most people with CFS get better over time, although some people do not make a full recovery. It is also likely there will be periods when your symptoms get better or worse. Children and young people with CFS are more likely to recover fully.