ME/CFS: Differential Diagnosis

This page needs to be updated – take everything with a grain of salt.

As always, this page is work in progress and currently just a scratch pad – and not very up to date.

A differential diagnosis is asking the question: "What else could it be?"

There are other diseases that at first glance look somehow similar to ME/CFS, so you want to find out if have it (instead of ME/CFS). Maybe you are lucky and find something that is treatable! Or it could be you find a comorbid condition, that when treated helps you to get better along with ME/CFS.

The basic rule of thumb: If you find something, treat it and your symptoms improve markedly, then you don't have ME/CFS. If you treat it and improve somewhat, then you have found something comorbid – keep treating it, but keep looking for the actual reason of your illness. If the treatment doesn't do what it should, then talk to your doctor and stop it, as you don't have this problem.

Like many things here, this list is work in progress.

Other infectious diseases

It is the first thing doctors think of, when they hear the symptoms of ME/CFS... One simple blood test.

It usually isn't HIV.

Hepatitis A/B/C ...

It is the second thing doctors think of, when they hear the symptoms of ME/CFS... You need to test your blood for each, so it makes it a bit more expensive. 

It is unclear to me whether (and how far) Hepatitis can mimic ME/CFS.

One simple blood test to Chlamydia trachomatis and one to Chlamydophila pneumoniae. If you have high titers* against one of those, your ME/CFS symptoms are caused by Chlamydia. Treat with antibiotics, NAC and probiotics – you should be fine. If your titers are normal or just "slightly elevated", then Chlamydia is not your main problem.

* Titers are the the measure of how strongly your body reacts to a given pathogen.

Very seldom, unless you are from a high risk group (come from Japan, Peru, the Pacific coast of Colombia and Ecuador, the Caribbean, Africa or northeastern Iran, or are IVdrug users, Inuit of Northern Canada, Native American or South American Indian)

Post-Polio Syndrome
People who had an polio infection can develop post-polio syndrome over time. Can be similar to ME/CFS, but seems to have some differences (possible involvement of motor neurons).

"Autoimmune" and inflammatory conditions, allergies

An autoimmune condition is one, where your immune system attacks a part of your own body. I have put it in quotes, because I don't think an immune system attacks its own body ("all by itself" as the name autoimmune suggests) without an outside insult, like something you eat or an virus you have.

Celiac disease (also spelled coeliac)
Besides other symptoms, Celiacs can drain your energy pretty badly. The good thing is, Celiac is currently the only autoimmune disease that has a known cause: Cereal Grain, the Gluten part of cereal grain to be precise. The cure? In short: Stop eating food that is made from grains or contains grains in some form. That is something one can try out, and see if it helps – no other diagnostic tests necessary. (Side-note: There are other conditions where grains can cause problems).


Rheumatoid arthritis
In Rheumatoid Arthritis your immune system attacks your joints and causes (besides other problems) inflammation (and pain) in your joints. In both ME/CFS and Fibromyalgia you tend to have mainly muscle pain (and not so much painfull joints), so one should be able to tell these conditions apart.

Having inflamed sinuses can be associated with substantial fatigue and pain.

Behçet’s disease
Sometimes, Behçet’s disease can be almost invisible to the naked eye because some patients have few if any mouth ulcers or any other visible signs of the disease. Behçet’s disease is basically an overactive immune system that causes inflammation of blood vessels – mainly the small blood vessels. Cardinal symptoms are profound fatigue, migraines, poly arthralgia or multiple joint pain just like arthritis.

Diseases of the hormone system
Side-note: Diseases of the hormone system usually have an autoimmune component.


Adrenal insufficiency

Psychiatric problems

Trauma / PTSD

Diseases of the central nervous system (CNS)

(Uni-Polar) depression

Bi-Polar depression

Multiple sclerosis (MS)

There is a lot that should be written about how to distinguish ME/CFS from cancer, so take this with some grain of salt: If your symptoms persist for a longer time, it probably isn't cancer



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