Will this be resolved?

Some of it probably will. Hydrogen sulfide has no published threshold at all, which is the kind of gap that gets filled once enough data exists. Whether the underlying testing approach survives is a larger question that is being argued now.

How do I talk to a doctor who thinks none of this is real?

Not by arguing about the label, which is the part they have a considered position on. Bring what is measurable: a symptom record with dates, any results with the method and substrate used, and specific questions about what a given test can and cannot show. That is a conversation about evidence rather than a contest about a name, and it travels much further.

Is it worth paying for a private test if the evidence is this weak?

Sometimes, and it turns on what you would do differently with the result. A test that would change a decision can be worth the money even when the underlying evidence is thin. A test that produces a number nobody will act on is expensive reassurance. Deciding in advance which of the two you are buying is the step people skip.

Why the diagnostics here are contested

By B. Gray Randolph · Updated August 6, 2026

If you have read six articles and come away more confused, that is the correct response to the material. It is not a gap in your reading.

What contested actually means here

The short answer

Specialists disagree about the tests, the criteria, and in some cases whether a condition exists as commonly described. That is different from saying your symptoms are not real. Symptoms are not what is in dispute. What is in dispute is what to call them, how to confirm it, and whether the tools used to do so actually work.

Most writing in this space resolves that discomfort by picking a side and sounding certain. We would rather name the disagreements, because knowing which argument you have wandered into is more useful than being handed one side of it.

There are four separate disagreements, not one

Collapsing them into "it's complicated" is what makes this feel unnavigable. They are distinct and they have different statuses.

1. Whether the main test should be used at all. This is a live argument in the literature rather than a fringe position, and it is worth reading alongside what each breath test can physically measure.

Kashyap P et al., Neurogastroenterology & Motility 2024 Peer-reviewed studyWe have not yet confirmed a direct link to this document, so we are not giving you one. The citation above is enough to find it, and we would rather say this than send you to a journal front page.

2. What the thresholds should be, where they exist. The published cutoffs are consensus figures agreed by a panel rather than numbers derived from outcome data. And for one of the three gases there is no threshold at all.

Rezaie A et al., American Journal of Gastroenterology 2017 Clinical guideline

3. How much the evidence supports current practice. The guideline is unusually candid about this, and it is the single most useful thing to know before reading anything else.

Pimentel M et al., American Journal of Gastroenterology 2020 Clinical guideline

All six recommendations conditional. Five of six resting on evidence its own authors grade as very low quality. That is not us being sceptical about a guideline; it is the guideline being explicit about itself.

4. Whether symptoms can identify anything. Tested directly, and they could not.

Scalese G et al., Journal of Clinical Medicine 2025 Peer-reviewed studyWe have not yet confirmed a direct link to this document, so we are not giving you one. The citation above is enough to find it, and we would rather say this than send you to a journal front page.

Symptoms did not significantly differ between test-positive and test-negative groups, and the two common tests agreed with each other on 8.7% of cases.

Why two clinicians can look at this and land in different places

The short answer

Because they are weighing the same weak evidence, and weak evidence supports more than one defensible reading. A guideline that grades most of its own recommendations as very low quality does not compel a single conclusion. One clinician reads that as a reason for caution, another as a reason to try something. Neither is being unreasonable.

This is worth internalising because the alternative explanation, that one of them is simply wrong or dismissive, is usually not what is happening and does not help you in the appointment.

What is not settled here

We are not neutral about everything here. Where a test is sold for a purpose a guideline says it cannot serve, we say so. Where a product category has no independent evidence, we say so. What we will not do is manufacture a resolution to a disagreement that specialists are still having, because a confident answer we cannot support is exactly the thing that made this hard for you to research.

How to read anything in this space, including us

Two filters do most of the work.

What does the source stand to gain? A clinic selling consultations and a brand selling supplements both have a reason to present contested things as settled. This is not an accusation of dishonesty; it is a structural observation about who can afford to say "we do not know".

Does the source acknowledge the disagreement at all? A page that presents any of this as resolved is either uninformed or selling. That single test filters most of what you will find.

Apply both to this site. We have no consults and no supplement line, which is why we can afford to leave things unresolved. What we do have is the intention to earn commission on some products eventually, which is disclosed, and which you should weigh.

What to do with this

Being clear that the uncertainty is real, rather than a failure of your research, changes what a good appointment looks like. The productive questions are about what a specific test can physically measure and what a specific result would rule out, because those have answers. Which contested label fits you frequently does not.

Common questions

Will this be resolved?: Some of it probably will. Hydrogen sulfide has no published threshold at all, which is the kind of gap that gets filled once enough data exists. Whether the underlying testing approach survives is a larger question that is being argued now.
How do I talk to a doctor who thinks none of this is real?: Not by arguing about the label, which is the part they have a considered position on. Bring what is measurable: a symptom record with dates, any results with the method and substrate used, and specific questions about what a given test can and cannot show. That is a conversation about evidence rather than a contest about a name, and it travels much further.
Is it worth paying for a private test if the evidence is this weak?: Sometimes, and it turns on what you would do differently with the result. A test that would change a decision can be worth the money even when the underlying evidence is thin. A test that produces a number nobody will act on is expensive reassurance. Deciding in advance which of the two you are buying is the step people skip.