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Related Conditions

pixabay question silhouettesME/CFS is not alone in its symptoms and presentation. In fact, there are quite a few conditions that seem to have similar features. But does that mean that the other condition is related to ME/CFS in some way?

The simplest way that a condition can be related to ME/CFS is when that condition is caused by ME/CFS itself. In this case, the other condition is referred to as a symptom of ME/CFS. For example, orthostatic intolerance is a condition that is also a symptom of ME/CFS. (And it may also be a symptom of other diseases as well!)

One more way that a condition can be related to ME/CFS is simply by appearing more frequently in ME/CFS patients than in the rest of the population. Such a condition is known as a common comorbidity. For example, fibromyalgia is a common comorbidity because it is found much more commonly in ME/CFS patients than in the rest of the population.

Another way that a condition can be related to ME/CFS is by having similar symptoms and presentation — despite being neither a symptom nor a common comorbidity. Such a condition is known as a differential diagnosis. For example, multiple sclerosis has similar symptoms and presentation as ME/CFS, but is considered to be a completely separate condition.

Finally, there may be any number of other ways that a condition can be considered a “related condition” to ME/CFS. In many cases, it remains profoundly unclear if the condition is truly a symptom, a common comorbidity, a differential diagnosis, or something else entirely!

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Examples of Related Conditions

To get an idea of some conditions that are related to ME/CFS, you can review the following relevant discussions from our community forum:

Long Covid:

Here we try to collect together all the discussions that might be relevant to “Long Covid”, the condition(s) that many people end up with, months after an infection with the novel coronavirus. These people are often referred to as “Long haulers”.

Brain inflammation and viral infection of the brain have been documented in acute COVID. But could the virus persist in the brain? And what might this mean for Long Covid? Could there be a more subtle type of neuroinflammation in Long Covid?

Some patients with Long Covid suspect that their ongoing symptoms are due to the coronavirus persisting in their body. A scientific publication took a close look at this possibility.

Six different research groups have now independently reported persistence of the coronavirus – inside the gastrointestinal tract – for many months after infection!


Fibromyalgia is perhaps the most well-recognized common comorbidity in ME/cfs. But how much do you know about the current diagnostic criteria for fibromyalgia? Did you know that the core symptoms include physical/mental fatigue and unrefreshing sleep? Did you know that the diagnostic criteria lists cognitive dysfunction (brain fog) as a “major feature” and hypersensitivities to light, sound, odors, etc. as “common complaints” in fibromyalgia?

Fibromyalgia has many overlaps in symptoms with ME/cfs. Following the 2014 finding of neuroinflammation in ME/cfs, a Harvard research team looked at fibromyalgia patients and also found neuroinflammation in fibromyalgia!

One study found that fibromyalgia patients may have antibodies that attack the Dorsal Root Ganglia (DRG). The DRG are the pain processing nodules that run along the spinal cord. What is the impact of inflammation in the DRG?

Lyme disease:

There has been a long, acrimonious debate about whether the bacterium that causes Lyme Disease can persist in the human body after multiple rounds of antibiotics. New case studies show that it is indeed possible. But just how common is this phenomenon?

Peripheral neuropathy:

How common is peripheral neuropathy in ME/cfs? And what are the different types of peripheral neuropathy for an ME/cfs doctor to consider?

Small Fiber Neuropathy (SFN):

How can you tell if you have the type of peripheral neuropathy known as Small-Fiber Neuropathy (SFN)?  And is there a connection between SFN and orthostatic intolerance in ME/cfs?

Irritable Bowel Syndrome (IBS):

If you are an ME/cfs patient with Irritable Bowel Syndrome (IBS) and dysautonomia, do you notice any correlation between your IBS symptoms and your dysautonomia symptoms? A few studies seem to suggest that IBS might be a form of dysautonomia.

Small Intestinal Bacterial Overgrowth (SIBO):

Some ME/cfs patients are diagnosed with Small Intestine Bacterial Overgrowth (SIBO). Although there are treatments, SIBO often returns after each treatment.  Could SIBO be related to dysautonomic control of intestinal movement?

Hypermobility or Ehlers-Danlos-Syndrome (hEDS):

One study found that up to 50% of patients with ME/cfs had evidence of joint hypermobility, which may indicate reduced collagen in the joints. What might be the possible relation to Intracranial Hypertension (IH) or Craniocervical Instability (CCI)?

A study found that ME/cfs patients with joint hypermobility had a larger drop in blood flow to the brain on standing than ME/cfs patients without hypermobility. Could this effect be due to reduced collagen surrounding blood vessels?

When collagen is reduced, blood vessels lose their protective outer support. This might make blood vessels liable to being pinched, restricting blood flow and leading to vascular compression syndromes. What are the types of vascular compression syndromes most often seen?

Mast Cell Activation Syndrome (MCAS):

Mast Cell Activation Syndrome (MCAS) is a diagnosis that is increasingly being applied to situations where mast cells are unusually activated. But what might cause this unusual activation in the first place?

Post-Concussion Syndrome (PCS):

A common question that people ask is: “Are there any other conditions that also come with Post-Exertional Malaise (PEM)?” One such condition that seems to be mentioned regularly is Post-Concussion Syndrome (PCS).

Hashimotos’s thyroiditis:

Hashimoto’s Thyroiditis is a common comorbidity in people with ME/cfs. What sorts of issues arise with diagnosis, management and treatment?

Is there a relation between Hashimoto’s Thyroiditis and the viruses that trigger ME/cfs?

Periodic Paralysis:

Periodic Paralysis is a condition that occasionally has genetic origins, but not always. Paralysis is the main symptom, but since fatigue and muscle pain are also symptoms of Periodic Paralysis, how can you tell if you have Periodic Paralysis?

Exocrine Pancreatic Insufficiency:

Pancreas problems sometimes occur in ME/cfs patients, including low-level pancreatitis and Exocrine Pancreatic Insufficiency (EPI). In EPI the pancreas fails to release enough digestive enzymes, so the intestines have trouble absorbing nutrients from food, leading to other problems due to insufficient nutrients. If EPI is properly diagnosed and treated, could it improve other symptoms?


We all know the stigma of ME/cfs all too well. But ME/cfs is not the only stigmatized neuroimmune illness triggered by infections. Hear the sad story about a boy suffering from PANS (Pediatric Acute-onset Neuropsychiatric Syndrome).

“Functional” Neurological Disorder (FND):

Have you ever been diagnosed with a “Functional Neurological Disorder”? Do you think that diagnosis was correct? Is “Functional Neurological Disorder” just the newest re-branding of old, discredited, psychiatric biases?

Acute Flaccid Paralysis (AFP) is a sudden onset of weakness or paralysis in the limbs that appears to be linked to viruses. Many countries have consistently reported yearly cases of AFP to the World Health Organization for years, but not the United States. What is happening in the United States? Are the cases of AFP being misdiagnosed as “Functional Neurological Disorder”?

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