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INTRODUCTION — Chronic fatigue syndrome (CFS) is a disorder that causes unexplained, persistent, and sometimes debilitating fatigue. It is also known as myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). There is evidence of underlying abnormalities in the nervous system, the immune system, and metabolic function in people with the condition. However, it can be difficult to diagnose CFS due to the general nature of the symptoms and the lack of a definitive diagnostic test.
At this time, there is no specific therapy for CFS, which can make living with the condition frustrating. The goal of treatment is to manage symptoms. Also, research on how the disorder affects people over time has yielded somewhat conflicting results. Some people notice an improvement in their symptoms over time, while others get worse. Regardless of its long-term prognosis, CFS does not result in organ failure.
CHRONIC FATIGUE SYNDROME SYMPTOMS — Persistent fatigue that can be overwhelming is a hallmark of chronic fatigue syndrome (CFS). The fatigue may develop suddenly, often after an infection such as an upper respiratory infection (eg, the common cold or flu) or mononucleosis ("mono"). However, in some people, fatigue may develop gradually over several months. The fatigue can produce substantial impairment in your ability to function at home or at work, is not substantially relieved by resting, and must be present for more than six months in order to be diagnosed as CFS. (See 'Chronic fatigue syndrome diagnosis' below.)
Other important features include:
●Post-exertional malaise – This is the term for a prolonged worsening of symptoms after certain stressors such as physical exertion, using a lot of mental energy (for example, doing your taxes), or standing for a long time.
●Unrefreshing sleep – This is typically characterized by awakening feeling unrefreshed nearly every morning.
●Memory and concentration problems.
●Orthostatic intolerance – This is when symptoms worsen when you stand up and maintain an upright posture and improve (though not necessarily resolve) when you lie down.
Many patients with CFS also report other symptoms, such as:
●Aching joints
●Aching muscles
●Nausea
●Sore throats
●Headaches
People with CFS often experience feelings of anger, frustration, and depression. This may be due in part to the lack of an accurate diagnostic test and proven treatment. In addition, you may feel that others don't take your illness seriously or think that you are making up or exaggerating your symptoms. This may lead you to wonder if there is really anything wrong with you, which can be distressing. However, it is important to know that expert institutions, such as the Institute of Medicine of the National Academy of Sciences, have concluded that CFS is a real, physical illness; your symptoms are not imaginary.
The symptoms of CFS also can occur with other medical conditions. For this reason, if you have persistent fatigue or related symptoms, it's very important to see a health care provider to rule out other potential causes. However, CFS can also occur at the same time as other illnesses, which can make diagnosis challenging. (See 'Chronic fatigue syndrome diagnosis' below.)
POSSIBLE CAUSES OF CHRONIC FATIGUE SYNDROME — Despite extensive research, the cause of chronic fatigue syndrome (CFS) is not known. The illness sometimes follows a new infection, such as with Epstein-Barr virus (EBV) infection or Lyme disease, but there is no proof that these infections cause the ongoing symptoms of the illness. In addition, there is research showing that extended courses of treatment for infections such as Lyme disease are of no benefit. Most experts think it is unlikely that a single infectious agent causes the illness.
Some have speculated that allergies, chemical sensitivities, and body-wide yeast infection may cause the illness, but in carefully done research studies, none of these have been proven to cause CFS.
Several other potential causes of CFS are being studied. There is some evidence suggesting that CFS may be an immune disorder, meaning your immune system (which normally fights infections) is malfunctioning and causing your symptoms. Another line of research has focused on chronic hypotension (low blood pressure) caused by a problem in the nervous system. There is growing evidence that the cells of the body are not able to produce enough energy in people with this illness, although the cause of this deficiency remains unknown.
Although the underlying cause of CFS has not been identified, doctors understand that the syndrome and its symptoms are real.
CHRONIC FATIGUE SYNDROME RISK FACTORS — There are some groups of people who seem to be at higher risk for developing chronic fatigue syndrome (CFS):
●Although CFS can occur in people of all ages, it more often begins in young and middle-aged adults than in children or older adults.
●CFS is diagnosed about twice as often in females as in males.
The people who seek care for CFS are more often white (non-Hispanic) people, but studies in the community conducted by the United States Centers for Disease Control and Prevention (CDC) have found that the illness may actually be more frequent in African Americans, Native Americans, and people of lower income. It appears to be less common in Asian Americans.
The actual incidence of CFS may be underestimated in certain populations. For example, symptoms in older people may often be attributed to other coexisting health problems. In addition, people from lower socioeconomic groups may have more limited access to health care, and therefore may be less likely to seek help for CFS symptoms.
CHRONIC FATIGUE SYNDROME DIAGNOSIS — There is no test that is accurate enough to definitively diagnose chronic fatigue syndrome (CFS). CFS is diagnosed based on your medical history (including a review of the duration and severity of your symptoms) and physical examination.
Criteria for diagnosis proposed by the United States National Academy of Medicine are summarized here and discussed in greater detail above (see 'Chronic fatigue syndrome symptoms' above):
●Persistent fatigue
●Post-exertional malaise
●Unrefreshing sleep
●Memory and concentration problems
●Orthostatic intolerance
To be diagnosed with CFS, the above symptoms must have been present for at least six months with moderate, substantial, or severe intensity at least one-half of the time.
Your health care provider might suggest blood or urine testing to rule out other conditions, but these are not required to diagnose CFS. For example, if your provider suspects that you might have sleep apnea (which can also lead to fatigue), he or she may recommend a sleep study. Similarly, if your history or exam suggest that certain hormone levels may be low (a disease called adrenal insufficiency, which can also cause fatigue or weakness), you may be tested for that as well. (See "Patient education: Sleep apnea in adults (Beyond the Basics)" and "Patient education: Adrenal insufficiency (Addison's disease) (Beyond the Basics)".)
If you have unexplained chronic fatigue but few, if any, of the additional symptoms discussed above, you may have unexplained or "idiopathic" chronic fatigue. This is considered to be a different problem and may be managed differently than CFS.
CHRONIC FATIGUE SYNDROME TREATMENT
General approach — There is no cure for chronic fatigue syndrome (CFS); instead, the goal of treatment is to reduce symptoms of the illness and help improve your quality of life. Many therapies have been tried in CFS, but none have been consistently successful.
In general, treatment must be individualized to first address the symptoms that are most bothersome for you or interfere most with your life (see 'Chronic fatigue syndrome symptoms' above). As an example, for some people, treatments may include medications that help to treat pain and sleep problems (eg, nonsteroidal anti-inflammatory drugs [NSAIDs] or a low dose of a medication called amitriptyline).
For people who are able to tolerate it, continuing to be physically active is likely to be helpful. However, it is important to work with your health care providers to determine the type and amount of activity that is most likely to be of benefit for you, as well as to understand your personal limits when it comes to physical activity.
Treatments that are unproven or of unclear benefit — A number of different behavioral, dietary, and medication interventions have been evaluated for the treatment of CFS. Some have been found to be of no benefit; for others, the benefit is unclear.
In the past, many health care providers recommended a certain type of exercise therapy (called "graded exercise therapy") for people with CFS. However, this was based on a study that has been criticized for having significant limitations, and many people with CFS find that this type of exercise makes their symptoms worse. Although it might be worth trying an exercise program, this needs to be done with care and in consultation with your health care provider so you can avoid exacerbating your symptoms. People with CFS yearn for their prior active lives and are at risk for "overdoing" exercise.
Cognitive behavioral therapy (CBT) may be helpful for some, but not all, people with CFS. It typically involves a series of one-hour sessions with a psychotherapist or counselor, which focuses on discussing beliefs and behaviors that can interfere with your recovery. While CFS is not a mental health disorder, and CBT will not cure it, it's possible that CBT may help you to better cope with your fatigue. It might also help with other symptoms such as difficulty sleeping. As with graded exercise therapy, the value of CBT in people with CFS is controversial, as serious questions have been raised about how the largest study of these therapies was conducted.
You may also have heard of medications, supplements, or dietary changes that claim to treat or cure CFS. However, these are not proven to improve symptoms, they can be costly, and they can have serious side effects, so health care providers do not recommend them. They include:
●Medications such as antibiotics (eg, doxycycline), antiviral drugs (eg, acyclovir), glucocorticoids (also called steroids), and antihistamines used to treat heartburn
●Vitamin, mineral, or herbal supplements such as magnesium, evening primrose oil, vitamin B12, and bovine (cow) or porcine (pig) liver extract
●Exclusion diets, in which certain foods are eliminated or limited
●Removal of dental fillings
LIVING WITH CHRONIC FATIGUE SYNDROME — Living with chronic fatigue syndrome (CFS) can be frustrating and stressful, as the symptoms can affect your quality of life. Most people who develop CFS were generally healthy and active previously, which can make it particularly distressing.
In addition, many people, including health care practitioners, have a limited understanding of why or how CFS develops, and it is unclear how best to treat your symptoms. Although no specific treatment for CFS exists, it is important to keep in mind that CFS is not a new disease and that experts are continuing to gain experience, knowledge, and insight as they study it.
The most important factor in your ability to successfully cope with CFS is establishing a strong relationship with an experienced health care provider. Having a provider you can trust, who listens to you and understands that your symptoms are real, can be validating and helpful. While it is discouraging to know that there is no quick cure for CFS, an experienced provider can work with you to find ways to manage your symptoms and maximize your quality of life.
WHERE TO GET MORE INFORMATION — Your healthcare practitioner 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: Myalgic encephalomyelitis/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 myalgic encephalomyelitis/chronic fatigue syndrome
Postural tachycardia syndrome
Treatment of myalgic encephalomyelitis/chronic fatigue syndrome
The following organizations also provide reliable health information.
