In order to arrive at a diagnosis of CFS, it is necessary to follow the systematic procedure, recommended by a panel of CFS experts.

The first step, is obtaining a detailed medical history, followed by a complete physical examination.

The next is assessment of the mental status of the patient. This can be achieved by a short oral test or a brief discussion.

This would be followed by a battery of lab tests (blood and urine tests) to identify alternative causes of fatigue, if any.

If the test results raise suspicion of any other disorder, additional tests may have to be done to confirm the diagnosis, based on which further treatment can be instituted.

If no other cause for the fatigue is obtained from the multidisciplinary approach, a diagnosis of CFS would be made, provided the symptoms correlate with the CFS definition.

A diagnosis of CFS can be arrived at, only if the following two criteria are satisfied.

Extreme fatigue that results in a substantial reduction in the functionality of an individual, which cannot be attributed to exertion, and not relieved by rest.

The presence of sore throat, impaired memory or ability to concentrate, tender lymph nodes (cervical/axillary), muscle pain, joint pain, new type of headaches, unrefreshing sleep, depression or malaise following exertion. Here again, 4 or more of the above mentioned symptoms should be present for a period of 4 months or more, to confirm the CFS diagnosis.

If the patient's symptoms are less severe, or if the criteria for CFS diagnosis are not satisfied, the patient is said to have idiopathic (of an unexplained cause) chronic fatigue.