Chronic Fatigue Syndrome Symptoms, Causes and Diagnosis

Fatigue, Muscle Pains, and Headaches May Suggest CFS

Chronic fatigue syndrome can lead to symptoms of tiredness, muscle aches, and concentration problems and the causes vary
Chronic fatigue syndrome can lead to symptoms of tiredness, muscle aches, and concentration problems and the causes vary. Getty Images

Chronic fatigue syndrome is characterized by unexplained prolonged fatigue that is not improved by rest and may be worsened by physical or mental activity. This fatigue can be severe and incapacitating, causing a substantial reduction in daily activities. This impairment affects occupational, personal, social, or education activities. Learn about the associated symptoms, causes, and diagnosis of chronic fatigue syndrome (CFS) and what other medical conditions should be excluded, including sleep disorders.

Who Gets Chronic Fatigue Syndrome (CFS)?

One to 4 million Americans suffer from CFS. Approximately 40% of those with symptoms of CFS actually have an unrecognized medical or psychiatric condition (including diabetes, thyroid disease, and substance abuse). Although it can affect anyone, CFS is four times as common in women compared to men, and most typically occurs in people in their 40s and 50s.

What Are the Characteristic Symptoms of Chronic Fatigue Syndrome?

In addition to incapacitating fatigue lasting greater than 6 months and the exclusion of other medical conditions, individuals with CFS concurrently have four or more of the following symptoms:

  • Post-exertional malaise lasting more than 24 hours (relapse of symptoms after physical or mental exertion)
  • Unrefreshing sleep
  • Substantial impairment in memory or concentration
  • Persistent muscle pain
  • Pain in multiple joints without swelling or redness
  • Headaches of a new type, pattern, or severity
  • Sore throat
  • Tender neck or armpit lymph nodes

Are There Other Associated Symptoms?

In addition to the characteristic symptoms described above, many symptoms occur in about 20% to 50% of people with CFS. These additional symptoms may include:

  • Abdominal pain
  • Alcohol Intolerance
  • Allergies or sensitivities to foods, alcohol, odors, chemicals, medications or noise
  • Balance problems
  • Bloating
  • Chest pain
  • Chills
  • Chronic cough
  • Diarrhea
  • Dizziness
  • Dry eyes or mouth
  • Earaches
  • Fainting
  • Irregular heartbeat
  • Jaw pain
  • Morning stiffness
  • Nausea
  • Night sweats
  • Psychological problems (depression, irritability, mood swings, anxiety, panic attacks)
  • Shortness of breath
  • Skin sensations
  • Tingling sensations
  • Visual disturbances (blurring, sensitivity to light, eye pain)
  • Weight loss or gain

What Are the Causes of Chronic Fatigue Syndrome?

The cause of CFS is not clearly understood at this time. Current research is evaluating a number of potential causes, including: infection, immunological factors, hormonal factors, neurological problems, and nutritional deficiencies.

How Is Chronic Fatigue Syndrome Diagnosed?

No diagnostic tests are available at this time. It is important to rule out other potential causes of profound fatigue prior to accepting CFS as the diagnosis. Therefore, one must not self-diagnose CFS as other potentially dangerous conditions may be the true cause.

One must be evaluated by a knowledgeable health care provider who takes a careful history, conducts a physical examination, and orders the necessary laboratory tests to rule out other potential causes of your symptoms.

There are two diagnostic criteria:

  1. Have severe chronic fatigue for six months or longer with other potential medical conditions excluded.
  2. Must concurrently have four or more of the diagnostic symptoms described above. These symptoms must have persisted or recurred during six or more consecutive months of illness and must not have predated the fatigue.

What Are Similar Medical Conditions that Must Be Excluded?

CFS can resemble many other disorders with similar symptoms. It is common for people to mistakenly assume they have CFS when they have another illness that needs to be treated. The following conditions should be excluded before a diagnosis of CFS is given:

  • Alcohol or substance abuse
  • Autoimmune disease
  • Bipolar affective disorder
  • Cancer
  • Chronic hepatitis
  • Chronic mononucleosis
  • Diabetes
  • Eating disorder
  • Fibromyalgia syndrome
  • Hormonal disorder
  • Hypothyroidism
  • Lupus
  • Lyme disease
  • Major depression
  • Multiple chemical sensitivities
  • Multiple sclerosis
  • Myalgic encephalomyelitis
  • Narcolepsy
  • Neurasthenia
  • Obesity
  • Reactions to prescribed medications
  • Schizophrenia
  • Sleep apnea
  • Subacute infections

The Importance of Persistence

As there is no specific test for CFS and fatigue is a symptom common to many illnesses, it is sometimes frustratingly difficult to obtain the accurate diagnosis. It is an invisible illness and patients may not look sick. Additionally, it often has a pattern of remission and relapse, and symptoms may vary greatly from one affected person to the next.

It is estimated that of the four million Americans with CFS, less than 20% have been appropriately diagnosed. Therefore, it is important to be educated about this potential condition, and persistent about pursuing appropriate evaluation and treatment. Research suggests that early recognition of this disease can increase the likelihood of improvement.


Chronic Fatigue Syndrome. Centers for Disease Control and Prevention, Department of Health and Human Services. Last accessed: March 27, 2016.

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