Symptoms:

Symptoms of CFS are similar to those of the flu and other common viral infections, and include muscle aches, headache, and extreme fatigue. However, symptoms of CFS last for 6 months or more.

The main symptom of CFS is extreme tiredness (fatigue), which is:

• New
• Lasts at least 6 months
• Not relieved by bed rest
• Severe enough to keep you from participating in certain activities

Other symptoms include:

• Feeling extremely tired for more than 24 hours after exercise that would normally be considered easy
• Feeling unrefreshed after sleeping for a proper amount of time
• Forgetfulness
• Concentration problems
• Confusion
• Joint pain but no swelling or redness
• Headaches that differ from those you have had in the past
• Irritability
• Mild fever (101 degrees F or less)
• Muscle aches (myalgias)
• Muscle weakness, all over or multiple locations, not explained by any known disorder
• Sore throat
• Sore lymph nodes in the neck or under the arms

Signs and tests:

The Centers for Disease Control (CDC) describes CFS as a distinct disorder with specific symptoms and physical signs, based on ruling out other possible causes.

CFS is diagnosed after your health care provider rules out other possible causes of fatigue, including:

• Drug dependence
• Immune or autoimmune disorders
• Infections
• Muscle or nerve diseases (such as multiple sclerosis)
• Endocrine diseases (such as hypothyroidism)
• Other illnesses (such as heart, kidney, or liver diseases)
• Psychiatric or psychological illnesses, particularly depression
• Tumors

A diagnosis of CFS must include:

• Absence of other causes of chronic fatigue
• At least four CFS-specific symptoms
• Extreme, long-term fatigue

There are no specific tests to confirm the diagnosis of CFS. However, there have been reports of CFS patients having abnormal results on the following tests:

• Brain MRI
• White blood cell count