Table of ContentsView AllTable of ContentsChange to SEIDSymptomsCauses
Table of ContentsView All
View All
Table of Contents
Change to SEID
Symptoms
Causes
SEID is diagnosed based on the presence of three core symptoms: impaired day-to-day functioning due to fatigue, malaise after exertion (physical, cognitive, or emotional), andpoor sleep quality. Problems with memory and attention, as well asorthostatic intolerance, which causes dizziness upon standing, are also characteristic of SEID.
This article describes the causes and symptoms of systemic exertion intolerance, along with why the name chronic fatigue syndrome was changed to SEID.
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From Chronic Fatigue Syndrome to SEID
SEID means systemic exertion intolerance disease. When something is systemic, it affects the entire body. “Exertion intolerance” refers to the hallmark symptom of SEID, calledpost-exertional malaise.
Until 2015, SEID was known as chronic fatigue syndrome (CFS). Advocates of this disease have long called for a new name for two main reasons:
The use of “disease” in the new name marks the first time this illness has been recognized as adisease (as opposed to a syndrome).
It’s important to note that chronic fatigue syndrome has not been officially renamed as systemic exertion intolerance. The term “myalgic encephalomyelitis”/chronic fatigue syndrome is most commonly used in medical literature and clinical practice.
What is Myalgic Encephalomyelitis?
Symptoms of SEID
People with SEID experience:
Some people with SEID are able to tolerate mild or moderate levels of activity, while others are unable to even take care of their most basic needs without consequences to their health.
At times, people with severe SEID may be:
According to a survey of people with SEID, almost all people surveyed reported having difficulty performing daily tasks. About 94% of those surveyed experienced moderate or extreme pain, 89% of people had trouble with mobility, and 64% had trouble with washing or dressing themselves.
What Causes SEID?
While the exact cause or causes of SEID are unknown, a few possible causes have been identified.
Increasing research shows that SEID usually begins following an infection. In fact, up to 80% of people with SEID develop the disease following a viral illness.
Viral infections that have been identified as SEID triggers include:
People with these infections who develop very severe symptoms appear to be more likely than those with mild symptoms to develop SEID.
There have also been reports of people developing SEID after the following:
Some evidence suggests that SEID may run in families. Twin studies have shown show higher rates of SEID in identical, rather than fraternal, twins. More specific genetic causes have not been identified.
Summary
SEID stands for systemic exertion intolerance disease. SEID was previously known as chronic fatigue syndrome or myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). Advocates of the disease pushed to change the name of the disease to SEID to more accurately encompass the full-body symptoms it causes. People with SEID experience a worsening of physical and cognitive symptoms following even mild physical, emotional, mental, and/or orthostatic stress. The exact cause of SEID is unknown, although up to 80% of people with SEID developed it after a viral illness.
5 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.The Lancet.What’s in a name? Systemic exertion intolerance disease.The Lancet. 2015 Feb;385(9969):663. doi:10.1016/S0140-6736(15)60270-7Twisk F.Replacing myalgic encephalomyelitis and chronic fatigue syndrome with systemic exertion intolerance disease is not the way forward.Diagnostics. 2016;6(1):10. doi:10.3390/diagnostics6010010Mount Sinai.Chronic fatigue syndrome.Arron H, Marsh B, Kell D, Khan M, Jaeger B, Pretorius E.Myalgic encephalomyelitis/chronic fatigue syndrome: The biology of a neglected disease.Front Immunol. 2024 Jun;15(1). doi:10.3389/fimmu.2024.1386607Centers for Disease Control and Prevention.Clinical overview of ME/CFS.Additional ReadingCommittee on the Diagnostic Criteria for Myalgic Encephalomyelitis/Chronic Fatigue Syndrome; Board on the Health of Select Populations; Institute of Medicine.Beyond Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: Redefining an Illness. National Academies Press (US); 2015 Feb.
5 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.The Lancet.What’s in a name? Systemic exertion intolerance disease.The Lancet. 2015 Feb;385(9969):663. doi:10.1016/S0140-6736(15)60270-7Twisk F.Replacing myalgic encephalomyelitis and chronic fatigue syndrome with systemic exertion intolerance disease is not the way forward.Diagnostics. 2016;6(1):10. doi:10.3390/diagnostics6010010Mount Sinai.Chronic fatigue syndrome.Arron H, Marsh B, Kell D, Khan M, Jaeger B, Pretorius E.Myalgic encephalomyelitis/chronic fatigue syndrome: The biology of a neglected disease.Front Immunol. 2024 Jun;15(1). doi:10.3389/fimmu.2024.1386607Centers for Disease Control and Prevention.Clinical overview of ME/CFS.Additional ReadingCommittee on the Diagnostic Criteria for Myalgic Encephalomyelitis/Chronic Fatigue Syndrome; Board on the Health of Select Populations; Institute of Medicine.Beyond Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: Redefining an Illness. National Academies Press (US); 2015 Feb.
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
The Lancet.What’s in a name? Systemic exertion intolerance disease.The Lancet. 2015 Feb;385(9969):663. doi:10.1016/S0140-6736(15)60270-7Twisk F.Replacing myalgic encephalomyelitis and chronic fatigue syndrome with systemic exertion intolerance disease is not the way forward.Diagnostics. 2016;6(1):10. doi:10.3390/diagnostics6010010Mount Sinai.Chronic fatigue syndrome.Arron H, Marsh B, Kell D, Khan M, Jaeger B, Pretorius E.Myalgic encephalomyelitis/chronic fatigue syndrome: The biology of a neglected disease.Front Immunol. 2024 Jun;15(1). doi:10.3389/fimmu.2024.1386607Centers for Disease Control and Prevention.Clinical overview of ME/CFS.
The Lancet.What’s in a name? Systemic exertion intolerance disease.The Lancet. 2015 Feb;385(9969):663. doi:10.1016/S0140-6736(15)60270-7
Twisk F.Replacing myalgic encephalomyelitis and chronic fatigue syndrome with systemic exertion intolerance disease is not the way forward.Diagnostics. 2016;6(1):10. doi:10.3390/diagnostics6010010
Mount Sinai.Chronic fatigue syndrome.
Arron H, Marsh B, Kell D, Khan M, Jaeger B, Pretorius E.Myalgic encephalomyelitis/chronic fatigue syndrome: The biology of a neglected disease.Front Immunol. 2024 Jun;15(1). doi:10.3389/fimmu.2024.1386607
Centers for Disease Control and Prevention.Clinical overview of ME/CFS.
Committee on the Diagnostic Criteria for Myalgic Encephalomyelitis/Chronic Fatigue Syndrome; Board on the Health of Select Populations; Institute of Medicine.Beyond Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: Redefining an Illness. National Academies Press (US); 2015 Feb.
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