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Patient education: Systemic exertion intolerance disease (chronic fatigue syndrome) (Beyond the Basics)

Stephen J Gluckman, MD
Section Editor
Mark D Aronson, MD
Deputy Editor
Jennifer Mitty, MD, MPH
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Systemic exertion intolerance disease (SEID), also known as chronic fatigue syndrome (CFS), is a disorder that causes unexplained, persistent, and sometimes debilitating fatigue.

Living with SEID/CFS can be frustrating because most people, including healthcare providers, have a limited understanding of why or how SEID/CFS develops. In addition, there are limited treatment options. Although SEID/CFS is not likely to shorten your life, it can have a profound effect on your quality of life.

More detailed information about SEID/CFS is available by subscription. (See "Clinical features and diagnosis of systemic exertion intolerance disease (chronic fatigue syndrome)" and "Treatment of systemic exertion intolerance disease (chronic fatigue syndrome)".)


Persistent fatigue is the hallmark of systemic exertion intolerance disease (SEID), also known as chronic fatigue syndrome (CFS).

Typically, the fatigue develops suddenly, often following an infection such as upper respiratory infection or mononucleosis. (See "Patient education: Infectious mononucleosis (mono) in adults and adolescents (Beyond the Basics)".)

You have overwhelming fatigue and a number of additional symptoms.

Physical activity makes the symptoms worse.

Typically, people who develop SEID/CFS were functioning at a high level previously. You do not have a history of worrying excessively about being ill. You do not have multiple physical complaints, such as chronic back ache, chronic headache, and so on.

Many, if not most, people with SEID/CFS have physical symptoms for which no cause can be found with an examination and/or testing. In addition to the fatigue, you may have one or more of the following:

An increase in fatigue after exercise or exertion

Memory and concentration problems

Difficulty sleeping

Dizziness when you stand up

The bodywide nature of symptoms and lack of an identifiable cause can make coping with this disease difficult. People may suspect that you are making up the symptoms, and you may wonder if there is really anything wrong with you. Consequently, feelings of anger, frustration, and depression are common with SEID/CFS.

The signs and symptoms of SEID/CFS can also occur with other medical conditions. Thus, it is essential to see a healthcare provider and have other potential causes ruled out. However, SEID/CFS can also occur at the same time as other illnesses.


The cause of systemic exertion intolerance disease (SEID), also known as chronic fatigue syndrome (CFS), is not known. Past explanations for SEID/CFS have included chronic Epstein Barr virus infection, Lyme disease, total allergy syndrome, multiple chemical sensitivity syndrome, bodywide yeast infection, and viruses called xenotropic murine leukemia virus-related virus (XMRV) and murine leukemia virus. However, in carefully done research studies, none of these conditions has been proven to cause SEID/CFS. (See "Clinical features and diagnosis of systemic exertion intolerance disease (chronic fatigue syndrome)".)

Several other potential causes of SEID/CFS are being studied. There is some evidence suggesting that SEID/CFS is an immune disorder, causing the body's defense system to function abnormally. This does not mean that the immune system is weakened, however.

Another line of research has focused on chronic hypotension (low blood pressure) caused by a problem in the nervous system.


There are some groups of people who seem to be at higher risk for developing systemic exertion intolerance disease (SEID), also known as chronic fatigue syndrome (CFS).

SEID/CFS is diagnosed more often in young and middle-aged adults than in children or older adults.

SEID/CFS is diagnosed about twice as often in women as in men, and is also more likely to be diagnosed in white (non-Hispanic) people compared with other ethnic groups.


Systemic exertion intolerance disease (SEID), also known as chronic fatigue syndrome (CFS), is usually diagnosed based upon a medical history and physical examination. Blood or urine testing may be done to rule out other conditions, but are not needed to diagnose SEID/CFS.

In order to be diagnosed with SEID/CFS, you must have unexplained, persistent, or relapsing fatigue, plus a number of the additional problems listed above. (See 'Symptoms' above.)

If you have unexplained chronic fatigue but few, if any, of these additional symptoms, you may have unexplained chronic fatigue. This is considered to be a different problem and is managed differently than SEID/CFS.


There is no cure for systemic exertion intolerance disease (SEID), also known as chronic fatigue syndrome (CFS); the goal of treatment is to reduce symptoms of fatigue and help you to cope. Many therapies have been tried in SEID/CFS but none has been consistently successful. Cognitive behavioral therapy and graded exercise appear to be the most effective treatments. (See "Treatment of systemic exertion intolerance disease (chronic fatigue syndrome)".)

Cognitive behavioral therapy — Cognitive behavioral therapy (CBT) is a type of therapy that can help to reduce symptoms of chronic fatigue syndrome. It typically involves a series of one-hour sessions with a psychotherapist or counselor. The sessions focus on discussing beliefs and behaviors that can interfere with your recovery. CBT will not cure SEID/CFS, but it can help you to cope better with your fatigue.

Graded exercise — Although exercise can sometimes make SEID/CFS symptoms worse, a prolonged lack of exercise can also worsen SEID/CFS. Experts recommend beginning with gentle exercises and slowly increasing the intensity. Working with a professional trainer who is familiar with SEID/CFS may be of benefit.

Antibiotics — You or your clinician may be tempted to try a course of antibiotics, especially if you happen to have a positive blood test for Lyme disease. A positive Lyme test, however, merely indicates that you have been exposed to the bacteria that causes Lyme disease. It does not mean that your symptoms are related to Lyme disease. (See "Patient education: Lyme disease symptoms and diagnosis (Beyond the Basics)".)

There is no role for antibiotics in the treatment of SEID/CFS, and there is the potential for serious side effects from prolonged use of antibiotics.

Treatment for fibromyalgia — Fibromyalgia is a condition that causes muscle and joint pain without an identifiable cause. Given the similarity between SEID/CFS and fibromyalgia, many physicians believe that they are the same disease with different primary symptoms. Some clinicians treat both illnesses, beginning with education and one or more medications. (See "Patient education: Fibromyalgia (Beyond the Basics)".)

Unproven treatments — Treatments that are not proven to improve symptoms of SEID/CFS include the following:

Medications – This includes antidepressant medications, antibiotics, and antiviral drugs, including doxycycline, amantadine, and acyclovir, medications that affect the immune system, glucocorticoids (also called steroids), and cimetidine or ranitidine (antihistamines used to treat heartburn)

Vitamin, mineral, or herbal supplements – These include magnesium, evening primrose oil, vitamin B12, and bovine (cow) or porcine (pig) liver extract

Exclusion diets, in which certain foods are eliminated or minimized

Removal of dental fillings

Medications used to treat human immunodeficiency virus


Although no specific treatment for SEID/CFS has been established, it is important to understand that SEID/CFS is not a new disease, and that there is considerable knowledge and experience with SEID/CFS. Some points to remember include:

The severity of SEID/CFS is variable, but the symptoms are real and the condition can be completely incapacitating. The symptoms are not made up. Because there are no laboratory or other tests to prove the existence of SEID/CFS, many people struggle with the validity of their disease (as do their healthcare providers, family members, friends, and employers).

There is no point to debating whether symptoms of SEID/CFS originate in your mind or are the result of a not-yet identified abnormality. If the cause is in your mind, the symptoms are no less real (a difficult concept for some patients and/or their families). If the cause is an abnormality in your body, it is not yet known how to find it or treat it.

Most people with SEID/CFS have some degree of depression. Depression can be successfully treated, and treatment can help people with SEID/CFS to cope better. (See "Patient education: Depression treatment options for adults (Beyond the Basics)".)

Research into the long-term course of SEID/CFS has yielded somewhat conflicting results. Some patients have an improvement in their symptoms over time while others worsen. Regardless of the long term prognosis, SEID/CFS does not result in organ failure or death.

The most important factor in your ability to successfully cope with SEID/CFS is establishing a strong relationship with an experienced healthcare provider. This should include trust on both sides and a willingness to believe that SEID/CFS is both real and disabling.


Your healthcare provider is the best source of information for questions and concerns related to your medical problem.

This article will be updated as needed on our website (www.uptodate.com/patients). Related topics for patients, as well as selected articles written for healthcare professionals, are also available. Some of the most relevant are listed below.

Patient level information — UpToDate offers two types of patient education materials.

The Basics — The Basics patient education pieces answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials.

Patient education: Fibromyalgia (The Basics)
Patient education: Systemic exertion intolerance disease (chronic fatigue syndrome) (The Basics)

Beyond the Basics — Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are best for patients who want in-depth information and are comfortable with some medical jargon.

Patient education: Infectious mononucleosis (mono) in adults and adolescents (Beyond the Basics)
Patient education: Lyme disease symptoms and diagnosis (Beyond the Basics)
Patient education: Fibromyalgia (Beyond the Basics)
Patient education: Depression treatment options for adults (Beyond the Basics)

Professional level information — Professional level articles are designed to keep doctors and other health professionals up-to-date on the latest medical findings. These articles are thorough, long, and complex, and they contain multiple references to the research on which they are based. Professional level articles are best for people who are comfortable with a lot of medical terminology and who want to read the same materials their doctors are reading.

Approach to the adult patient with fatigue
Clinical features and diagnosis of systemic exertion intolerance disease (chronic fatigue syndrome)
Postural tachycardia syndrome
Treatment of systemic exertion intolerance disease (chronic fatigue syndrome)

The following organizations also provide reliable health information.

National Library of Medicine

Centers for Disease Control and Prevention

(404) 639-3311

Chronic Fatigue and Immune Dysfunction Syndrome Association of America


Literature review current through: Sep 2016. | This topic last updated: Jun 29, 2015.
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