How common is chronic fatigue syndrome (CFS)?

Studies show that anywhere between one and four million people in the United States currently meet the criteria for chronic fatigue syndrome. Because many cases of this condition are undiagnosed and because the guidelines doctors use to diagnose it are not set in stone, that number may be much higher. Original estimates that around 38 out of 100,000 Americans meet the criteria for chronic fatigue syndrome have been thought to be an understatement.
Jacob Teitelbaum
Integrative Medicine

There is a fair bit of controversy and misunderstanding surrounding how common CFS is. This is because if a person has "exclusionary conditions" (any other condition that might conceivably also cause fatigue), then he or she is very unlikely to be diagnosed as having chronic fatigue syndrome. (An anology to this would be if exclusionary conditions such as these were similarly used for metastatic cancer, over three quarters of people would be incorrectly eliminated from being diagnosed with cancer.) In my experience, and in many studies, most people who have chronic fatigue syndrome also have fibromyalgia and vice versa. An estimated 2-4% of the population has fibromyalgia. And this has been rising rapidly over the last decade.

Experts think at least one million Americans have CFS. Fewer than 20 percent of these cases have been diagnosed, however.

Women are four times as likely as men to develop CFS. The illness occurs most often in people ages 40 – 59. Still, people of all ages can get CFS. CFS is less common in children than in adults. Studies suggest that CFS occurs more often in adolescents than in children under the age of 12.

CFS occurs in all ethnic groups and races, and in countries around the world. People of all income levels can develop CFS, although there is evidence that it is more common in lower-income than in higher-income persons. CFS is sometimes seen in members of the same family, but there is no evidence that it is contagious. Instead, it may run in families because of a genetic link. Further research is needed to explore how this happens.

This answer is based on source information from National Women's Health Information Center.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.