Diagnosing Chronic Fatigue Syndrome

Diagnostic Criteria Narrowed to 4 Characteristic Features

A doctor reviews a chart with a patient.
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Chronic fatigue syndrome (CFS), also known as myalgic encephalomyelitis, can be a frustrating condition as it is not only misunderstood by the public but incredibly difficult to diagnose. As a syndromic illness, CFS is characterized by its symptoms; there is no single test available to confirm the disease.

Complicating the issue even further is the fact that many of the symptoms of CFS mirror other illnesses, including heart, lung, thyroid, and even psychiatric disorders.

Because of this, some people doubt that the disease actually exists. But, according to a report from Centers for Disease Control and Prevention, as many as 2.5 million people in the U.S. are affected by CFS.

As a disease, CFS is diagnosed when all other possible causes have been explored and excluded. There is no treatment or cure for CFS. To date, no medical specialty has officially claimed the condition as their own. There is not even a known cause of CFS.

Symptoms of Chronic Fatigue Syndrome

From a broad perspective, CFS is typified by persistent exhaustion and a general feeling of unwellness that will not go away. A person will wake up tired, even with ample sleep, and go to bed tired. From a syndromic standpoint, the symptoms include:

  • Fatigue
  • Memory impairment
  • Difficulty concentrating
  • Sore throat
  • Enlarged lymph nodes in the neck or armpits
  • Muscle pain (myalgia)
  • Joint pain (arthralgia)
  • Headaches
  • Extreme exhaustion after mental or physical exercise

Because the symptoms are so nonspecific, they can be easily attributed to any number of medical conditions from dietary deficits to life-threatening illnesses.

Diagnosing Chronic Fatigue Syndrome

The diagnosis of CFS is made by exclusion, meaning that a doctor will explore every likely condition for which a person may experience fatigue, body aches, swollen lymph nodes, and cognitive impairment.

The list is potentially exhaustive, and the process can be lengthy and sometimes tedious. The evaluation may involve tests for the following conditions:

Even if a positive diagnosis of depression is made, it doesn't necessarily rule out CFS since depression is an almost inextricable symptom of long-term fatigue. As such, the diagnosis needs to be made by a doctor experienced in CFS who is better able to differentiate the physiological symptoms from the psychological ones.

2015 Diagnostic Criteria

Recent efforts have been made to provide clarity on how CFS can be positively identified in people with persistent fatigue. In 2015, the Institute of Medicine, now the National Academy of Medicine (NAM), issued an evidentiary report on CFS in which they proposed a new set of criteria to clarify the diagnostic process.

According to NAM, a person may be diagnosed with CFS if they meet all of the following criteria:

They also adopted a new name for the disorder: systemic exertion intolerance disease, or SEID.

A Word From Verywell

The frustration you may be feeling if living with CFS is understandable. We don't know what causes it, the diagnostic process is complex, and the treatment options are few.

With all of this to consider, it may be seem pointless to get tested at all.

But don't give up. The simple fact is that the expansive testing may reveal an unexpected cause for which there may, in fact, be treatment.

On the other hand, if all other causes are excluded and it is CFS, there are ways to improve long-term outcomes with cognitive training and graded exercise. Just take it one step at a time. The more you know, the more choices you have.


Centers for Disease Control and Prevention. " Diagnosing CFS." Atlanta, Georgia; updated November 7, 2017.

Maes, M.; Anderson, G.; Morris, G. et al. "Diagnosis of myalgic encephalomyelitis: where are we now?" Expert Opin Med Diagn. 2013;7(3):221-5. DOI: 10.1517/17530059.2013.776039.

National Academy of Science. (2015) Beyond Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: Redefining an Illness. Washington, D.C: National Academy of Science Health and Medical Division.