The nine conditions this site covers
The short answer
These nine produce overlapping symptoms and get mistaken for one another routinely. Several are defined by symptoms rather than confirmed by a test, which is the structural reason the confusion happens rather than a failure of anyone involved. Start from a label here, or start from the pair you are trying to separate.Start from a label
- Small intestinal bacterial overgrowth23 pages
An overgrowth of bacteria in the small intestine, diagnosed in practice by a breath test that measures gases rather than bacteria. Where that gap matters, and what it does not rule out.
- Mast cell activation syndrome8 pages
A syndrome with two competing sets of diagnostic criteria that do not agree. What each one requires, what that disagreement means for you, and what it overlaps with.
- Histamine intolerance5 pages
A proposed reaction to dietary histamine with no agreed confirmatory test. Why the published food lists contradict each other, and what the blood test does and does not show.
- Irritable bowel syndrome3 pages
IBS is defined by symptom criteria and by ruling other things out, not by a test that confirms it. Why that makes overlapping labels so common.
- Food intolerance5 pages
A reproducible reaction to a food that does not use the immune mechanism of an allergy. Which means the common tests are answering a different question.
Covered, but not yet in depth
These four appear on our comparison pages but do not yet have enough behind them to be worth a page of their own. Saying so is more useful than building four thin pages that look like coverage.
Long COVID gut symptoms
Digestive symptoms that persist after a COVID infection, which overlap heavily with several of the other labels here and arrived recently enough that the literature separating them is thin.
Postural orthostatic tachycardia syndrome
A disorder of autonomic regulation, defined by a measured heart rate response to standing. It appears alongside gut symptoms often enough that it belongs in any honest account of what overlaps with what.
Candida overgrowth
A widely marketed explanation for diffuse symptoms. The organism is real and genuinely causes disease in defined settings. The version sold to the general public is a much broader claim than the one those settings support.
Mold illness
A contested label applied to multi-system symptoms attributed to mold exposure. It carries an unusually heavy commercial apparatus of tests and protocols relative to what is established.
Common questions
- Why do these conditions get confused with each other?
- Because several of them are defined by symptoms rather than confirmed by a test, and the symptoms overlap heavily. Two of the labels here are explicitly diagnoses of exclusion, which means what you end up being called can depend on which other things were looked for first.
- Can you have more than one of these at once?
- People commonly carry more than one of these labels, and our comparison pages are written on that assumption rather than treating them as alternatives. What is much harder to establish is whether one caused another, and in most cases the honest answer is that the order cannot be recovered after the fact.
- Why do only some of these have their own page?
- A page collecting a single article is not a hub. Five of the nine are referenced by enough of our published work to be worth starting from, and the other four are listed here with the pages that actually cover them. When one of those four reaches three pages it gets promoted automatically.