Chronic fatigue syndrome can be misdiagnosed or overlooked because its symptoms are common to other many disorders. Fatigue, for instance, is found in hundreds of illnesses. The nature of the symptoms, however, can help distinguish CFS from other illnesses.

Primary Symptoms

As the name chronic fatigue syndrome suggests, this illness is accompanied by fatigue. However, it's not the kind of fatigue we experience after a particularly busy day or week, after a sleepless night or after a single stressful event. It's a severe, incapacitating fatigue that isn't improved by bed rest and that may be worsened by physical or mental activity. It's an all-encompassing fatigue that results in a dramatic decline in both activity level and stamina.

People with CFS function at a significantly lower level of activity than they were capable of prior to becoming ill. The illness results in a substantial reduction in occupational (work-related), personal, social or educational activities.

The fatigue of CFS is accompanied by characteristic symptoms lasting at least six months. These symptoms include:

• difficulties with memory and concentration
• problems with sleep
• persistent muscle pain
• joint pain (without redness or swelling)
• headaches
• tender lymph nodes
• increased malaise (fatigue and sickness) following exertion
• sore throat

Other Symptoms

The symptoms listed above are the symptoms used to diagnose this illness. However, many CFS patients may experience other symptoms, including:

• irritable bowel
• depression or psychological problems (irritability, mood swings, anxiety, panic attacks)
• chills and night sweats
• visual disturbances (blurring, sensitivity to light, eye pain)
• allergies or sensitivities to foods, odors, chemicals, medications or noise
• brain fog (feeling like you're in a mental fog)
• difficulty maintaining upright position, dizziness, balance problems or fainting

It's important to tell your health care professional if you're experiencing any of these symptoms. They may be related to CFS, or they may indicate that you have another treatable disorder. Only a health care professional can diagnose CFS.

What's the clinical course of CFS?

The severity of CFS varies from patient to patient, with some people able to maintain fairly active lives. For most symptomatic patients, however, CFS significantly limits work, school and family activities.

While symptoms vary from person to person in number, type and severity, all CFS patients are functionally impaired to some degree. CDC studies show that CFS can be as disabling as multiple sclerosis, lupus, rheumatoid arthritis, heart disease, end-stage renal disease, chronic obstructive pulmonary disease (COPD) and similar chronic conditions.

CFS often follows a cyclical course, alternating between periods of illness and relative well-being. Some patients experience partial or complete remission of symptoms during the course of the illness, but symptoms often reoccur. This pattern of remission and relapse makes CFS especially hard for patients to manage. Patients who are in remission may be tempted to overdo activities when they're feeling better, which can actually cause a relapse.

The percentage of CFS patients who recover is unknown, but there is some evidence to indicate that the sooner a person is treated, the better the chance of improvement. This means early diagnosis and treatment are important.