If you’ve had SIBO breath test results come back “negative” — but your symptoms haven’t gone anywhere — you’re not crazy.
This is something I see all the time.
People go through the process, complete breath testing, wait for the results… and then get told everything looks normal. Meanwhile, they’re still dealing with small intestinal bacterial overgrowth symptoms —bloating, discomfort, constipation or diarrhea, food reactions, and a gut that just doesn’t feel right.
So they’re left wondering: if my test is normal, why do I still feel like I have SIBO?
The truth is, SIBO breath tests are not as straightforward as they seem.
In many cases, the issue isn’t the test itself – it’s how the results are interpreted. When interpretation relies too heavily on rigid cutoffs or summary boxes, it can miss the broader pattern. When evaluated more thoughtfully, these tests can provide highly meaningful insights and significantly guide treatment decisions.
That doesn’t mean the test is useless — in fact, when it’s interpreted properly, it can be one of the most insightful and game-changing tools for someone who’s been struggling with irritable bowel syndrome symptoms for a long time. It just means you have to know what you’re looking at.
In this post, I’m going to walk you through the most common ways SIBO breath tests can come back “negative” even when something is clearly going on — and how to actually make sense of your results so you’re not left guessing.
Why the Type of Sugar Used in Your SIBO Test Matters
Before we get into that, it helps to understand what a small intestinal bacterial overgrowth (SIBO) breath test is actually measuring. After a period of fasting, you drink a sugar solution, which microbes ferment, producing gases like hydrogen or methane. These gases are then measured in each breath sample over a 2–3 hour period, and the timing of when they rise helps give insight into where fermentation may be occurring along the digestive tract.
One of the most overlooked reasons for a “false negative” SIBO test is simply the type of test that was used.
Most breath tests for SIBO use either glucose or lactulose as the substrate, and they behave very differently in the body. This is why glucose-based breath testing and lactulose-based testing can give you very different results depending on where overgrowth is occurring. Glucose is absorbed relatively quickly in the small intestine, so it may not reach the portions further down in the gut where overgrowth can sometimes occur. If bacterial overgrowth is sitting further downstream in the bowel, the glucose never reaches it, and the test can come back negative even when something is clearly going on.
Lactulose works differently. It is not absorbed in the small intestine, so it continues through the gut and is fermented by bacteria further down in the small intestine and in the colon. That allows us to see fermentation patterns along the full length of the digestive tract, giving a more complete picture of what’s happening further along the small intestine.
This becomes especially important when we’re talking about methane-dominant overgrowth, or intestinal methanogen overgrowth (IMO). Methanogens aren’t just confined to one specific spot in the gut and may be present more broadly throughout the intestinal tract, which is part of why the term IMO is now used. Because of this wider distribution, a glucose-based breath test may not always capture the full picture of methane activity.
An easy way to think about this is like checking only the front half of a tunnel and assuming nothing is happening further down. Just because you don’t see anything at the entrance doesn’t mean there isn’t activity deeper inside.
This doesn’t mean one test is always better than the other, but it does mean they can give you very different information depending on where small bowel bacterial overgrowth is happening.
One client I worked with—we’ll call her Kelly—came in dealing with pretty classic methane-type symptoms. She had significant bloating that got worse as the day went on, ongoing constipation, and a level of brain fog that was really starting to affect her day-to-day.
She told me she had already been tested for SIBO, and had even started exploring SIBO treatment options with her doctor, but then her test came back negative, which left her feeling stuck and, honestly, pretty frustrated. She felt like SIBO still made sense for what she was experiencing, but didn’t know where to go from there.
As I always do, I asked to see the actual test results myself. It took a bit of back and forth with her doctor’s office, but she was eventually able to get a copy. When I reviewed it, I saw that it was negative and that glucose had been used as the substrate.
I explained to her that glucose can catch a lot of cases, especially when overgrowth is happening earlier in the small intestine, but it can miss methane when it’s occurring further along the digestive tract. And with what we now understand about intestinal methanogen overgrowth (IMO), that’s not uncommon.
Since it had been a few months anyway, we decided to retest using lactulose to get a more complete picture.
Sure enough, her follow-up test showed a clear methane overgrowth that wasn’t visible on the original test—appearing later in the timeline in the third hour, exactly where a glucose test wouldn’t have picked it up.
From there, we were able to move forward with a targeted plan. As we worked through addressing the overgrowth, her bloating improved, her brain fog lifted, and for the first time in a long time, she was able to have regular bowel movements without relying on Miralax. We were also able to reintroduce foods without her reacting to everything, and put together a plan to help prevent things from coming back.
If your symptoms still feel all over the place, what you’re eating day to day can make a big difference while you sort this out.
We put together a simple, realistic SIBO diet plan that walks you through what to focus on (and what not to overcomplicate).
Download it here: SIBO 7-day Meal Plan
Some Tests Are Obvious… Many Are Not
Some tests are more straightforward than others. In some cases, results clearly meet diagnostic criteria based on current guidelines and are fairly easy to interpret in context.
One pattern you may see is something called a “double peak,” where hydrogen rises early in the test and then rises again later. This has historically been described in lactulose breath testing, where the early rise was thought to reflect small intestinal fermentation and the later rise colonic fermentation.
Here’s what that pattern can look like in practice, but it’s important to remember it’s just one possible presentation, not the only one. Breath tests can show a range of different patterns, and clinically relevant results don’t always follow this exact shape.
Notice how the line rises early, dips, and then rises again later. This is a pattern that has historically been interpreted as fermentation occurring first in the small intestine and then later in the colon. It’s one example of how breath test patterns can look, but it’s not the only presentation you’ll see in hydrogen-dominant SIBO.
Or methane that’s elevated across the entire test — what we typically see in methane SIBO patterns — steady, consistent, often well above normal, without much fluctuation. I call this a “high and sustained” presentation.
This is the classic constipation pattern. Methane stays elevated the entire time, which tells us it’s continuously slowing motility.
These are what I think of as slam dunk positives. They check every box, match textbook criteria, and are almost always flagged correctly as positive SIBO test results.
But many real-world tests don’t look like that. They’re not clean, they’re not obvious, and they don’t always follow the exact pattern the lab is programmed to detect.
Instead, they fall into a gray area where something is clearly off, but not in a way that gets labeled “positive.”
This is where I see patients get missed.
I had a client, Megan, who came to me after being told her test was completely normal. She had daily bloating, chronic constipation, and frequent abdominal pain, and felt like food just sat in her system all day.
When we reviewed her test together, nothing technically spiked high enough to meet the standard cutoff. But her methane stayed at 6–8 parts per million (ppm) the entire time, which is below the 10 ppm threshold for methane positivity, though it can still be meaningful when we look at it alongside her symptoms and overall pattern.
That’s the difference between a lab interpretation and a clinical interpretation. The lab is asking whether the test meets criteria, while I’m asking whether the pattern actually explains what the patient is experiencing.
And a lot of the time, those are not the same question.
So while it’s helpful to recognize what a textbook positive looks like, it’s even more important to understand that many legitimate cases don’t present that way. That’s what we’re going to walk through next — the patterns that get missed, misread, or dismissed, even when they’re clinically meaningful.
Rigid Interpretation Rules Miss Real Patterns
This is where things start to break down.
Because the issue usually isn’t the test itself, it’s how the test is being interpreted. Most labs rely on strict cutoffs and simple rules, which can work well for obvious cases but fall short when patterns are more nuanced.
And in real life, they usually are.
When it comes to interpreting SIBO breath test results, these rigid rules often don’t reflect what’s actually happening in the body.
Hydrogen Rules: The 20 ppm Increase Problem
The standard rule for hydrogen — based on the North American Consensus — is a rise of at least 20 ppm within the first 90 minutes. If that doesn’t happen, the test is often labeled negative.
The problem is that this rule assumes you’re starting from a low baseline. It also assumes the solution moves through the small intestine within that 90-minute window, which isn’t always the case. In reality, transit time can be slower — sometimes closer to 120 minutes — especially in people dealing with constipation or impaired motility.
So if gas rises later, it may still be coming from the small intestine, but it gets dismissed because it falls outside that 90-minute cutoff. And if someone starts out already elevated, they may never rise an additional 20 ppm at all, even if levels are high throughout.
Elevated Baseline Hydrogen Can Completely Mask a Positive
One of the clearest examples of this is elevated baseline hydrogen. If hydrogen starts out high, the test may never meet formal criteria based on a rise from baseline, even when the overall pattern still suggests abnormal fermentation.
It’s not uncommon to see hydrogen start elevated and stay elevated throughout the test, yet the report still labels it as normal because there wasn’t a significant rise from baseline. In more extreme cases, I’ve even seen baselines in the 80–100 ppm range get labeled “normal” for that same reason.
Take a look at this test result from one of my patients for a second. Does anything look off to you?
Look at the box at the top and find the observed hydrogen (H₂) value — 100 ppm. Then look to the right of it… It’s marked “normal.”
Really? In what world is a hydrogen level of 100 considered normal?
This is exactly how these rules can fail. If you look at the actual data in the Results box at the bottom, her baseline hydrogen started at 81.16 ppm. Because the criteria require a rise of 20 ppm above baseline, her levels would have needed to reach over 101.16 ppm to be flagged as positive. Since it didn’t, the lab marked it as negative — despite her hydrogen being extremely elevated the entire time.
Clinically, this is nowhere near normal.
This was a client of mine — we’ll call her Kathy — and she was struggling with severe SIBO symptoms. She had severe diarrhea that kept her home, interfering with her ability to travel, spend time with her grandkids, and, honestly, just enjoy her retirement. She was losing weight, becoming depleted, and her quality of life had taken a major hit.
And yet, she was told her test was normal.
Kathy is Italian, and one of the things she shared with me early on was how much she missed cooking — garlic, onion, big family meals — all the things she had always loved. Food had become something she feared instead of something she enjoyed.
Once we addressed what was actually going on here, everything started to change for the better. Her symptoms improved, her digestion stabilized, and she was able to start expanding her diet again. She got back to eating, cooking, and living her life.
In fact, she ended up getting so busy traveling and enjoying herself again that we eventually lost touch — which, honestly, is one of my favorite outcomes.
Because this is the kind of case that highlights the real issue: the data was there the entire time. It just wasn’t being interpreted in a way that matched what was actually happening in her body.
Methane Cutoffs Are Too High
Most labs use a cutoff of 10 ppm to call a test positive, so if methane stays below that, it’s typically flagged as negative. But clinically, we see symptoms — especially constipation — starting much lower, often around 3 ppm and above, and some labs even note this nuance in their reports.
This is where interpretation really matters. You might remember the example we looked at earlier, where methane didn’t rise until the third hour, which alone could be missed on a 2-hour test.
Even in that same example, methane never rises above 10 ppm, so despite a clear pattern, it could still be labeled “negative” by standard lab criteria. And yet, this is exactly the type of pattern we often see in constipation-driven cases.
Some labs try to account for this nuance — for example, you may notice the methane box highlighted differently here, and in the full report, interpretation notes often mention that lower levels can still be clinically relevant in constipation cases. But even with that, many providers are still relying on the ≥10 ppm cutoff and would read this as normal, leading to that familiar “your test was negative” conversation.
Patients Often Never See the Full Picture
Most people are only told one word: negative. They’re not shown the baseline levels, the progression over time, or the overall pattern, so they miss everything that actually matters.
And that’s where a lot gets lost. Even in the examples we’ve walked through, the data told a very different story from the final label.
One client I worked with — we’ll call her Linda — came to me after getting her breath test results back and feeling confused. During our initial conversation, she told me, “I had some methane, but it wasn’t very high — it was only 11.” Which, if you’re just going off the cutoff of 10, sounds like a very mild elevation.
That’s exactly how she had been interpreting it. And this is why I always want to see the full test results — because what’s in the summary box is often only a small piece of what’s actually going on.
When I looked at the summary box on her report, it was easy to see how she came to that conclusion. It listed her methane as 11, her hydrogen as normal, and the combined result as normal, so of course, she thought this was just a slight elevation.
But when I reviewed the actual methane readings, it told a completely different story. Her levels were 76… 81… 78… 71… 82… and then up to 87 — a very high, sustained methane pattern the entire time.
What made this especially confusing is that the summary box wasn’t showing her actual methane levels — it was showing an increase of 11 ppm, likely calculated between two values. So instead of highlighting the fact that her methane was massively elevated throughout the test, the way the report summarized it completely distracted from what actually mattered.
She wasn’t wrong — she was just reading exactly what the report was telling her. And this is what I mean when I say patients don’t see the full picture, because the data is technically there, but the way it’s presented makes it incredibly easy to miss.
When I explained it to her, she was like, oh my God… no one has ever broken this down for me like this. And that moment is everything, because for the first time, her symptoms actually made sense.
Because interpretation matters just as much as the data itself. Two people can look at the exact same test and come to completely different conclusions depending on what they’re actually paying attention to.
This is why understanding these patterns — not just the final result — is so important.
If you’ve been told your test was “normal,” but this is sounding a lot like your experience, there’s usually more to the story.
This is exactly what we do in our work—review the full pattern, connect it to your symptoms, and map out what’s actually going on.
You can schedule a strategy call here to talk through your results and what working together would look like:
https://nutritionresolution.com/strategy-call/
What Happens in the Last Hour Still Matters
Elevated Fermentation Later in the Test Isn’t Always “Normal”
When gas levels rise in the last portion of the test, it’s often written off as normal large intestinal fermentation. And to a certain extent, that’s true — we do expect some fermentation once the substrate reaches the colon.
But in practice, some patterns go well beyond what we’d typically expect. You may see levels climb much higher or more aggressively in that final hour, which can suggest that something else is going on beyond just “normal digestion.”
You may notice the final reading wasn’t captured — that can happen in real-world testing and doesn’t change the overall pattern here.
In my experience working with clients, this kind of pattern often shows up alongside small intestinal overgrowth. It doesn’t necessarily mean everything is happening in the small intestine, but it can point to a broader imbalance in how fermentation is occurring throughout the gut, including the large intestine, and it’s something we take into account when interpreting the full picture.
This Still Connects to Symptoms
Even if that fermentation is happening later in the test, it doesn’t make it irrelevant. Patterns like this are often associated with symptoms like bloating, discomfort, and changes in bowel habits.
In some cases — like the example above — this pattern clearly meets criteria for SIBO. But in other cases, you may see a similar late rise that doesn’t technically meet the cutoff for a “positive” test.
Either way, it can still help explain why someone feels the way they do — especially when everything is being labeled as “normal.” And in a functional nutrition practice like ours, this is still something we would address, because it can absolutely be a meaningful driver of symptoms even outside of a formal SIBO diagnosis.
Transit Time Can Distort Results
Slow Transit Can Hide What’s Actually Happening
One of the most overlooked factors in SIBO testing is how quickly — or slowly — things are moving through your digestive system. Breath tests are read based on the idea that things move through the small intestine at a fairly consistent pace, but research shows this timing can vary quite a bit from person to person.
When transit is slow, the solution may not travel far enough during the testing window to fully interact with microbes further along the small intestine. As a result, gas production can appear minimal or delayed, even when overgrowth is present.
This is one of the reasons you may see what’s called a “flatline” pattern — where hydrogen and methane levels stay low or barely change throughout the test. Normally, we would expect to see gas levels rise later in the test, especially in the third hour, as the solution reaches the large intestine and feeds the bacteria that naturally live there.
On paper, a flatline often gets labeled as normal, but in the right clinical context, it can actually point to under-detection rather than the absence of an issue. We’ll break this down more in a later section, but slow motility is one of the factors that can contribute to this type of pattern.
At the same time, flatline patterns are not always about slow transit. In practice, we often think about other possibilities — like hydrogen sulfide — which we’ll walk through shortly. This is why looking at the full clinical picture matters, because a flatline pattern on its own doesn’t tell the whole story, and the surrounding symptoms help point us toward what’s actually driving it.
Fast Transit Can Make Results Look Positive When They’re Not
Just like slow transit can hide what’s happening, fast transit can distort the test in the opposite direction. If the solution moves too quickly through the small intestine, it may reach the large intestine earlier than expected.
When that happens, you can see an early rise in gas levels that looks like small intestinal fermentation, when it’s actually coming from the large intestine. On paper, this can meet criteria for a positive test, even though it’s not reflecting overgrowth in the small intestine.
This is one of the reasons timing alone doesn’t tell the full story. An early rise isn’t always SIBO — sometimes it’s just the substrate moving faster than expected and feeding bacteria further downstream.
This is where clinical context becomes essential. Symptoms, patterns, and the full test timeline all help determine whether that early rise is truly coming from the small intestine or not.
In our work at Nutrition Resolution, we’ll often look at transit time more directly, too. And yes, sometimes that literally means having someone eat something that will visibly show up in their stool so we can see how long it takes to move through — not glamorous, but incredibly telling. Because once you understand how fast (or slow) things are actually moving, it can completely change how you interpret what you’re seeing on the test.
What “Normal” Actually Looks Like
At this point, we’ve looked at a lot of patterns that can be missed or misinterpreted. But in order to really understand what’s abnormal, you have to know what normal actually looks like.
On a typical normal breath test, hydrogen levels stay low throughout the small intestine. Then, once the solution reaches the large intestine — usually in the third hour — you’ll see a rise as the bacteria that naturally live there begin to ferment it.
This is a normal test result from a patient of mine who was diarrhea-predominant. You’ll notice hydrogen stays low early on, then rises later in the test, which is exactly what we expect to see when fermentation is happening in the right place.
You may also notice that methane is not zero here. Earlier, we talked about how even lower levels of methane can be meaningful in constipation-predominant cases, but in someone with a diarrhea pattern like this, we rely much more on the traditional ≥10 ppm cutoff — and levels below that are not typically driving symptoms in the same way.
This is what a generally normal pattern looks like — low gas levels early, with fermentation happening later once the substrate reaches the large intestine.
When the pattern looks like this, and it aligns with a diarrhea presentation, it doesn’t point us toward SIBO as the driver. It tells us we need to zoom out and look elsewhere, rather than trying to force an overgrowth explanation where it doesn’t fit.
Flatline Patterns — Not Always “Normal”
A flatline pattern is exactly what it sounds like — little to no rise in hydrogen or methane across the entire test. On paper, this often gets labeled as normal because nothing crosses the typical thresholds used to call a test positive.
Before we go further, it’s important to understand what this test is actually measuring. Most 2–3 hour breath tests only measure two gases: hydrogen and methane. They are not directly measuring the third type of SIBO — hydrogen sulfide — which means there are scenarios where hydrogen is still being produced through fermentation, particularly later in the test as the substrate reaches the large intestine, but instead of accumulating and showing up, it’s being used to produce hydrogen sulfide and therefore doesn’t show up as elevated hydrogen.
So if we assume transit is normal for a moment, we would expect to see gas levels rise later in the test — especially in the third hour — as the solution reaches the large intestine and feeds the bacteria that naturally live there. If that rise doesn’t happen, it tells us something is interfering with what we would normally expect to see.
This is where hydrogen sulfide comes in. In these cases, hydrogen is still being produced, but certain bacteria are actually using that hydrogen to produce hydrogen sulfide instead. So instead of seeing hydrogen rise on the test, it stays flat — not because nothing is happening, but because that hydrogen is essentially being “used up” before it can show up on the results.
This is why flatline patterns can be so misleading. Both slow motility and hydrogen sulfide can result in a test being labeled “negative,” even when symptoms are significant.
This is where the symptom picture becomes essential. If someone has clear signs of slowed motility — like long-standing constipation or known motility issues — that can point more toward transit playing a role. But if motility seems relatively normal and symptoms include things like sensitivity to sulfur-containing foods (such as eggs, garlic, or onions), increased bloating or discomfort with those foods, body aches, fatigue, or a more “toxic” or unwell feeling overall, that can point more toward hydrogen sulfide as a contributor.
In some cases, using a three-gas breath test that measures hydrogen sulfide directly can help clarify this, but even then, interpretation and clinical context still matter.
Bottom line: a flatline does not mean normal — it means you have to look deeper.
Improper Prep vs True Patterns
Another factor that can influence breath test results is how the test is prepared for. Before a SIBO breath test, there’s usually a specific prep protocol that includes a low-fermentation diet the day before and an overnight fast, helping reduce leftover fermentation from earlier meals so the results are more accurate.
If that prep isn’t followed closely, it can affect the starting point of the test. Instead of beginning at a low baseline, gas levels may already be elevated before the test even really begins.
When that happens, one pattern you might see is a high baseline that gradually comes down with repeated readings. Rather than staying elevated, levels start high and then decrease as the test progresses, sometimes followed by a rise later once the substrate moves further along.
And honestly, I went digging through our files to find a clean example of this to show you… and couldn’t even find one. That’s how thorough we are when it comes to walking our patients through test prep. But if you imagine a graph where hydrogen starts elevated and then steadily comes down, that’s often a sign that something during the prep phase may have interfered with the results.
That pattern looks very different from what we see with true overgrowth. In methane-dominant cases, for example, levels tend to stay elevated and consistent across the entire test, not drop off after the first reading.
That distinction matters more than most people realize. A high baseline on its own can be misleading, and without looking at how the pattern evolves over time, it’s easy to misinterpret what’s actually going on.
This is why we always look at the full trend, not just the starting number. It helps prevent misinterpretation in both directions — avoiding both false positives from poor prep and missed patterns that actually reflect overgrowth.
Alternative Interpretation Approaches (Clinical Nuance)
Up to this point, we’ve been talking about standard interpretation rules — things like a 20 ppm rise in hydrogen or methane above certain thresholds. But in practice, those aren’t the only ways clinicians evaluate these tests.
There are alternative approaches that take a more nuanced view of what’s clinically meaningful. One example of a more nuanced, clinician-driven interpretation — often discussed in functional GI circles, including by Dr. Allison Siebecker — is looking at the combined total of hydrogen and methane rather than evaluating each gas in isolation.
In this approach, a combined hydrogen and methane level of 15 ppm or more within the first 120 minutes may still be considered clinically significant, even if it doesn’t meet the traditional criteria for a “positive” test.
That doesn’t necessarily mean it would be labeled as SIBO from a conventional or diagnostic standpoint. But from a functional perspective, it can still represent an overgrowth pattern that’s contributing to symptoms and worth paying attention to.
In our work at Nutrition Resolution, this is exactly the kind of nuance we look for. If the pattern is there and it aligns with what someone is experiencing, we don’t ignore it just because it doesn’t meet a strict cutoff. We take it into account and build a plan to help rebalance the gut environment and move things in the right direction.
This is really the bigger takeaway: strict criteria are helpful, but they’re not the only way to interpret these tests. The pattern, the timing, and the person sitting in front of you all matter just as much.
This doesn’t replace a formal diagnosis, but it does help us understand what may be contributing to symptoms and how to move forward.
We love testing, but only when it’s used in the context of stepping back, zooming out, and looking at the whole person — not treating the test in isolation.
Why This Matters
All of this matters more than most people realize, because these interpretation gaps don’t just stay on paper; they affect real people.
When a test gets labeled “negative,” the conversation often stops there. Patients are told everything looks normal, even when their symptoms clearly say otherwise. They hear things like, “your colonoscopy was normal, there’s no cancer,” or “it’s just IBS,” or “it’s probably just stress.”
And while those statements aren’t necessarily wrong, they often don’t explain why someone is still feeling the way they are.
So people are left trying to figure things out on their own, or worse, starting to question whether what they’re experiencing is even valid.
In many cases, the underlying issue is still there — it just wasn’t captured or interpreted in a way that reflects what’s actually going on. So symptoms persist, and people stay stuck in that cycle of trying things, not getting answers, and feeling like they’re missing something.
This is something we see all the time. People come to us after being told their test was normal, but when we take a closer look at the full pattern, their symptoms, and the bigger picture, it becomes clear that there was more going on than what was initially picked up in the interpretation.
That’s why understanding these patterns matters. Because a “negative” result doesn’t always mean nothing is there — it may just mean it wasn’t interpreted in the right context.
You may have heard that SIBO breath tests “aren’t accurate,” and in many cases, that perception comes from experiences like the ones we’ve walked through here. It’s not so much that the test itself is inherently flawed — it’s that there are a lot of nuances in how these results need to be interpreted. When those nuances are missed, it can lead to confusion, conflicting opinions, or results that don’t seem to match how someone feels.
If you’ve been told your test was normal, but your symptoms don’t line up, this is exactly the kind of situation we help people work through. You can schedule a strategy call here, where we’ll talk through what’s going on, and I can review your test results with you as part of that conversation and outline what a plan of working together could look like.
Conclusion
SIBO breath tests can be incredibly useful, but their value comes down to how they’re interpreted. They give us detailed data, and when you know how to read the full pattern in context, that data can be incredibly informative.
A “negative” result doesn’t automatically mean there’s no overgrowth or imbalance. As you’ve seen throughout this post, there are a number of ways these tests can miss or misrepresent what’s actually happening.
This is why we don’t look at tests in isolation. We look at the full picture — the patterns within the data, your symptoms, your history, and how everything connects.
Because when you move beyond just treating what’s flagged on a report and start addressing the underlying patterns and root drivers, you’re no longer stuck guessing. You’re working with a clearer understanding of what’s actually going on — and that’s often when people finally start making real, lasting progress.
If you’ve been feeling stuck or like your results don’t fully explain what you’re experiencing, this is exactly the kind of work we help people with every day. You can learn more or schedule a strategy call here to take the next step.
Frequently Asked Questions (FAQ)
What does it mean if my SIBO test was negative but I still have symptoms?
This is more common than people realize. A “negative” result doesn’t always mean nothing is going on — it may mean the pattern wasn’t interpreted in a way that reflects what’s actually happening. This is where more thorough SIBO test results interpretation can make a big difference.
What is considered a hydrogen breath test normal range?
Based on the North American Consensus, a hydrogen rise of less than 20 parts per million (ppm) within the first 90 minutes is typically considered “normal.” If levels don’t increase by at least 20 ppm in that early window, the test is often labeled negative.
That said, this is where things can get tricky. These cutoffs assume a low starting baseline and a predictable transit time — which isn’t always the case. As you saw throughout this post, patterns can still be clinically meaningful even when they fall within what’s labeled as the hydrogen breath test normal range.
Can SIBO test results be explained differently depending on who reviews them?
Yes — and this is a big part of the issue. SIBO test results explained by a lab are often based on strict criteria and cutoffs, while a clinical review looks at patterns, timing, and symptoms. That’s why two people can look at the same test and come to very different conclusions.
Do you need to follow a specific SIBO protocol to get better?
Not necessarily. While you’ll see a lot of standardized SIBO protocol approaches online, the most effective approach is one that’s tailored to the individual. It should be based on multiple factors — including the type of overgrowth (hydrogen, methane, or hydrogen sulfide), degree of elevation, symptom presentation, motility, digestion, and the overall gut environment. From there, the specific agents used, whether prescription or herbal, are selected accordingly. A more personalized strategy that accounts for these factors tends to be much more effective than following a one-size-fits-all plan.
What is the best treatment for SIBO?
Treatment for SIBO typically involves working with a healthcare provider to address the overgrowth itself, along with the underlying factors that allowed it to develop. That might include medications, supplements, and dietary strategies, depending on the individual case.
What should I do if my results don’t match how I feel?
If your symptoms are ongoing but your test was labeled “normal,” it’s worth taking a closer look at the full results rather than relying on the summary alone. This is exactly where a more detailed review can help connect the dots and clarify what’s actually going on.
Are SIBO breath tests the same as lactose breath tests?
No. While both use breath testing to measure gas production, they’re looking for different things. Lactose breath tests are designed to assess lactose intolerance, while SIBO tests evaluate bacterial overgrowth in the small intestine using different substrates like glucose or lactulose. The testing process may look similar, but what they’re measuring — and how the results are interpreted — is different.
Why do SIBO breath tests measure carbon dioxide?
Carbon dioxide is used as a check to make sure each breath sample is coming from deep lung (end-alveolar) air, which helps improve the accuracy of the measurement. This helps ensure that hydrogen and methane readings reflect true breath levels rather than being affected by shallow breathing or inconsistent technique. Without this quality check, results may be less reliable.
