Are Fibromyalgia and Chronic Fatigue Syndrome the Same Thing?

What are the Differences?

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Are Fibromyalgia and Chronic Fatigue Syndrome the Same Thing?

The symptoms of fibromyalgia and chronic fatigue syndrome are really similar, and so are a lot of the drugs, dietary supplements and lifestyle changes recommended for managing them. I saw something online saying that fibromyalgia is basically chronic fatigue syndrome with pain, but pain is listed as a possible symptom of chronic fatigue syndrome.

It's all left me really confused.

So are fibromyalgia and chronic fatigue syndrome the same thing? If not, what's the difference?


Probably not, but they're likely related.

The answer depends on who you ask. Some doctors believe they are the same or are different forms of the same condition, but this opinion seems to be waning as we learn more about both of them.

The prevailing theories at the moment are:

  1. These illnesses are part of the same illness spectrum but represent different points along it, or
  2. They're related, both falling under the heading of central sensitivity syndromes.

So, according to these theories, while they're not exactly the same thing, they're more like cousins or perhaps siblings.

To address what you saw online, about fibromyalgia being chronic fatigue syndrome with pain, that is a belief that some people have. However, that appears to be an over-simplification that ignores key differences.

For one, fibromyalgia doesn't have the flu-like symptoms of chronic fatigue syndrome, such as sore throat or fever.

Another important difference involves exercise intolerance. Multiple studies show that fibromyalgia can improve with careful, moderate exercise. (Too much exercise can make symptoms worse, so it has to be tailored specifically to everyone unique tolerance.)

However, the reaction to exercise in chronic fatigue syndrome is much more severe and, again, features flu-like symptoms not found in fibromyalgia. This hallmark symptom is called post-exertional malaise.

A factor that muddies the waters between these two conditions is that many doctors aren't well versed in diagnosing either of them. Since they're both diagnoses of exclusion and have such similar symptoms, you have to expect some misdiagnosis. Also, some people diagnosed with just one of them may actually have both. That means self-reported symptoms, like you see in blog comments or forums, may assign symptoms to the wrong illness.

For further comparison of the two conditions, read Is it Fibromyalgia or Chronic Fatigue Syndrome?

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