Why Does Chronic Fatigue Syndrome Have So Many Names?

CFIDS, ME/CFS, SEID...

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Question: Why Does Chronic Fatigue Syndrome have So Many Names?

Looking online, I've seen chronic fatigue syndrome called CFS, CFIDS, ME/CFS, or myalgic encephalomyelitis. And recently SEID? Why are there so many names for it, and what do they all mean?

Answer: Chronic fatigue syndrome goes by so many names for a couple of reasons. Mainly, a lot of patients, patient advocates, doctors and researchers believe the name "chronic fatigue syndrome" trivializes the disorder and leads to misconceptions and even a lack of research funding.

While they'd like to see a name that reflects the severity of the condition, since no one really understands the causes and mechanisms behind chronic fatigue syndrome, it's been difficult to come up with a name that's accurate and universally accepted.

The name CFIDS, which stands for "Chronic Fatigue and Immune Dysfunction Syndrome," became common several years ago, as patients and advocates tried to make the name of the condition more reflective of what's going on in the body. However, while research has identified some immune system irregularities, findings are inconsistent and we don't have solid evidence that it's a major cause of symptoms.

ME/CFS (sometimes CFS/ME) is now becoming popular. In many countries, the condition is called myalgic encephalomyelitis, which some researchers, patients and advocates believe is more diagnostically correct. In the United States, advocacy groups want to transition from CFS to ME by re-educating the public and medical community.

Their plan is to first use ME/CFS and then later drop CFS altogether. (See Myalgic Encephalomyelitis/Encephalopathy for an explanation of what that means medically.)

Complicating the debate, critics of the current name-change effort point out that we don't have enough evidence to prove that encephalomyelitis is significantly involved in chronic fatigue syndrome.

Many people have recommended holding off on a name changed until the mechanisms behind the condition are better understood.

In 2015, a new report came out that suggests changing the name to SEID, systemic exertion intolerance disease. Authors of the report acknowledge that it's not the perfect name but say that research supports it and it's an improvement over CFS. "Exertion intolerance" refers to a hallmark symptom: post-exertional malaise. Also, this marks the first time "disease" has been used for this condition in an official capacity.

Learn more: New Name, Criteria for Chronic Fatigue Syndrome.

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