Definition & Overview

Chronic fatigue syndrome (CFS) is a complex medical condition characterised by prolonged, persistent, and extreme tiredness or weariness that does not go away even with ample bed rest. It is unique because it cannot be attributed to any recognised physical or mental condition. People with CFS suffer from unexplained fatigue that prevents them from living a normal life or participating in ordinary activities. More than half are unable to go to work and many are on disability or temporary sick leave. Only about less than 20% work full-time.

Also commonly referred to as myalgic encephalomyelitis chronic fatigue syndrome (ME/CFS), the condition affects more than 1 million people in the United States. It is up to four times more common in women than men.

The condition causes a number of symptoms that can come on suddenly or develop over time. Such symptoms may come and go and can last for months or even years.

Causes of Condition

Although chronic fatigue syndrome has long been recognised as a medical condition, what causes it to develop remains unknown. However, scientists believe that it could be due to a combination of genetic and environmental factors, including:

  • Hormonal imbalances - Scientists are looking for links between chronic fatigue syndrome and hormonal imbalances, as both conditions tend to be more common in women. Hormones are chemicals that have a direct impact on how the organs and cells in the body function. Hormone fluctuations can occur due to unbalanced lifestyle, toxins, or during certain times in women’s lives, such as puberty and menopause.

  • Suppressed immune system - Most people diagnosed with chronic fatigue syndrome have disorders that affect the function of the immune system. It is believed that this condition, which makes a person more prone to infections and certain illnesses, plays a crucial role in the development of CFS.

  • Certain infections - Researchers are also establishing links between CFS and certain viral infections including Epstein-Barr, human herpes, and leukemia viruses.

  • Stressful events - Many patients report that their symptoms started after a time of great physical (such as undergoing surgery) or emotional stress (such as the death of a loved one or breakdown of a marriage).

Key Symptoms

Aside from persistent and debilitating fatigue that lasts for at least six months, CFS patients also present with the following signs and symptoms:

  • Multi-joint pain that occurs without redness or swelling

  • Enlarged lymph nodes in the armpits and/or neck

  • Inability to concentrate

  • Loss of memory

  • Muscle pain without an apparent cause

  • Persistent headache

  • Sore throat

  • Unrefreshing sleep

  • Depression

  • Social isolation

  • Increased work absences

  • Chronic sleep disorders, such as insomnia

  • Significant reductions in levels of physical activity

  • Malaise

  • Intense mental fatigue after physical or mental activities

CFS can be mild or severe. While some patients are able to live a relatively normal life, others are unable to care for themselves and are totally bed-ridden.

Who to See and Types of Treatments Available

Currently, there is no specific test used to diagnose chronic fatigue syndrome. Available medical tests are performed to rule out medical conditions that share the same symptoms. These include chronic infection, chronic sleep disorders, and mental health issues, such as severe depression. For this reason, getting a definitive diagnosis could be a long and arduous process for patients.

Patients are diagnosed with chronic fatigue syndrome if:

  • They present symptoms of CFS, particularly extreme and prolonged exhaustion that does not go away with ample bed rest

  • They have been suffering from the same symptoms for at least six months

  • Diagnostic tests are inconclusive and cannot identify the specific cause of their symptoms

There is currently no cure for CFS. Treatment focuses on relieving symptoms and attempting to improve the patient’s quality of life. Patients who are showing signs of depression and are unable to sleep are often prescribed with antidepressants and sleeping pills. Other medications that can be prescribed include anti-anxiety drugs, nonsteroidal anti-inflammatory drugs, and pain relievers. Some activities that have shown to help ease some symptoms include:

  • Low-impact exercises, such as yoga and tai chi

  • A healthy lifestyle – Patients are advised to stop smoking and avoid alcoholic drinks as much as possible. Eating a healthy, well-balanced diet and sleeping at least eight hours per day are also proven to help.

  • Avoiding stress

  • Psychological counseling, particularly for patients who show signs of depression and mental problems

Unfortunately, since the cause of chronic fatigue syndrome is yet to be established, there are no existing guidelines on how it can be prevented.

New studies are being conducted to fully understand what causes the condition. New treatments are also being tested to improve treatment outcomes. In addition, researchers are exploring ways to better help health providers quickly identify and diagnose the condition.


  • Chronic fatigue syndrome/myalgic encephalomyelitis. Chicago, Ill.: International Association for Chronic Fatigue Syndrome/Myalgic Encephalomyelitis.

  • Smith MEB, et al. Treatment of myalgic encephalomyelitis/chronic fatigue syndrome: A systematic review for a National Institutes of Health Pathways to Prevention workshop. Annals of Internal Medicine. 2015;162:841.

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