Interested in diving into more about SIBO testing? The Buyer’s Guide to SIBO Tests is exactly what you need.

There is a page on A Gutsy Girl called Testing

It’s full of all SIBO (and many other) testing options. 

Time-and-time again, I’m asked to discuss more about SIBO testing in particular. 

So let’s go – let’s get you the help you need.

But first, SIBO.

What is SIBO?

I can’t even keep track of the number of times I’ve written about SIBO on A Gutsy Girl. If you click HERE you’ll see that I have mentioned the term on 60+ pages worth of articles. 

Therefore, if you want to know anything and everything about SIBO, just search it on this website. 

Or…..grab a copy of Reasonable SIBO.

The information in this post (leading up to testing) is just the basics.

SIBO (small intestinal bacterial overgrowth) is a serious condition affecting the small intestine.

It occurs when bacteria that normally grow in other parts of the gut start growing in the small intestine. This causes pain and diarrhea.

It can also lead to malnutrition as the bacteria start to use up the body’s nutrients.

What are SIBO Symptoms?

There are many symptoms which can be used in diagnosing if someone is affected by SIBO. These symptoms include:

  • pain in the stomach, especially after eating
  • bloating
  • cramps
  • diarrhea
  • constipation
  • indigestion
  • regular feeling of fullness
  • gas

For a list of real-life SIBO signs and symptoms, click HERE to grab my top 8.

Buyer’s Guide to SIBO Tests

Click HERE to save the Buyer’s Guide to SIBO Tests for later.

Buyer's Guide to SIBO Tests #sibo #fodmap #guthealth lab symptoms

There are two main types of SIBO. Understanding this helps understand their role in testing.

  1. Hydrogen-Dominant SIBO
  2. Methane-Dominant SIBO

Note: Remember there is also the 3rd, Hydrogen-Sulfide SIBO.

When you have an overgrowth of bacteria in your small intestine, the carbs you eat do not get broken down before they reach the large intestine.

And during this time period, fermentation of those carbohydrates is happening.

This fermentation process releases hydrogen as a byproduct, so people with SIBO have elevated levels of hydrogen in their GI tract.

This is why one of the most effective methods for diagnosing SIBO is testing hydrogen levels in the gut using a breath test.

However, SIBO can also cause an increase in methane levels because the hydrogen feeds single-cell organisms in your gut called archaea, which produce methane.

This can reduce the hydrogen levels which explains why there can be a false negative hydrogen test result and still have SIBO.

High methane production is associated with constipation, and patients treated for a bacterial overgrowth saw an improvement in their bowel regularity.

Methanogens also lead to increased production and absorption of short-chain fatty acids. They’re also linked to higher rates of obesity. people with higher intestinal methane production had higher BMIs.

This is important because they respond differently to different treatment options.

Test for SIBO: Lab Testing Options

Moving right along….

What is the SIBO Breath Test?

Still the most common, the SIBO breath test determines if your SIBO is hydrogen or methane dominant. However, it can be a bit cumbersome.

You’ll need to fast for 12 hours, and breathe into a small balloon to measure the baseline levels of hydrogen and methane.

Then ingest a precise amount of sugar to feed the bacteria and repeat breath samples every 20 minutes for 3 or more hours to see if levels of hydrogen or methane increase.

If the hydrogen levels are high then you likely have hydrogen-dominant SIBO.

However, just because one gas is dominant doesn’t mean that only one type of gas is present. You can have both types of gas present, one is just more prevalent.

See the bottom of this post for detailed information on various SIBO breath tests.

If you’re wondering what the actual test is like, you can learn how via How to Do the SIBO Breath Test.

Organix Dysbiosis Test

This functional medicine lab tests the urine for by-products of yeast or bacteria in the small intestine.

If the small intestine is housing a yeast or bacterial overgrowth, byproducts will appear in your urine, indicating their presence.

This test is much easier for patients and only requires a single urine specimen.

However, it does not determine whether the SIBO is hydrogen or methane-dominant.

Note: this can be problematic because treating SIBO for hydrogen is different than for methane.

Comprehensive Stool Test

This is also a functional medicine lab test looking at the flora of the large intestines.

When elevated levels of bacteria are found, it could indicate a presence of SIBO.

The good thing about doing stool testing is that it can can help determine many different things at once.

While it can help narrow down to SIBO, it can also assist in the discovery of multiple gut infections at one time. Some of these include: Candida, SIBO, and parasites.

Symptoms Checklist

Sometimes, though it’s maybe the least effective way at determining whether or not one has SIBO, simply using the list of symptoms listed and looking at a patient’s health history helps the doctor make a conclusion.

SIBO Breath Test Options

An advancement in SIBO is that you can get breath tests online, at your own will (i.e. without a doctor’s order).

However, do make note that just because you can get the SIBO breath test done doesn’t mean you have the ability to engage with the next steps:

  1. interpreting the results
  2. getting rid of the overgrowth

But at least getting the test done is a step in the right direction.

Just look at this huge list.

Testing Online SIBO test #sibo #guthealth #ibs

But that is confusing, right?

So I dug in to break them down for you. If you click the links below and go to the website to order they give no information on the differences, which I think is a major downfall. 

It’s frustrating because it’s actually not that difficult to breakdown.

Four things about the SIBO breath tests listed below:

  1. They are all testing for SIBO.
  2. They are broken down by hours (that you’ll measure).
  3. There are various types: lactulose, glucose, fructose, and/or a combination of any/all.
  4. SIBO breath test manufacturer.

9 Online SIBO Breath Tests to Choose From

Click HERE to save this chart for later.

9 Online SIBO Testing Options Buyer's Guide to SIBO Tests #sibo #fodmap #guthealth

Small Intestinal Bacterial Overgrowth (SIBO) (900) 3-Hr Lactulose-BioHealth Kit

The small intestine has 3 main areas – the duodenum, jejunum, and ileum.

The 2-hour testing is able to look at the first 2 areas, however, it may miss any bacteria present at the end of the small intestine (ileum), before it transitions into the large intestine (aka the colon).

The 3-hour test will hit each of the three areas. 

Small Intestinal Bacterial Overgrowth (SIBO) (900-C) 2-Hr Lactulose-BioHealth Kit

This one is exactly the same as the 3-hour test, except that it’s only 2 hours. Therefore, I would not recommend this one.

Lactulose is a manmade sugar that humans cannot digest, but SIBO bacteria love.

Drinking lactulose will not cause the same “sugar-high” as sugars that humans can digest (like sucrose or fructose).

Lactulose is also used as a laxative, so some people may experience effects of needing to use the restroom during the test.

Sometimes people may feel the same kind of side effects as what would make them need to take a SIBO test in the first place (like bloating, gas), but some people do not experience any at all.

Small Intestinal Bacterial Overgrowth (SIBO) (901) 3-Hr Glucose-BioHealth Kit

This is a 3-hour test. But this time it is a test for glucose.

With the glucose challenge, absorption occurs faster so the test more accurately diagnoses proximal overgrowth, which is considered more specific to the bacteria of concern.

Most research I’ve done prefers the glucose over lactulose test.

Small Intestinal Bacterial Overgrowth (SIBO) (901-C) 2-Hr Glucose-BioHealth Kit

This test is for 2 hours, and still for glucose. I’ve described both above.

Small Intestinal Bacterial Overgrowth (SIBO) (910) 3-Hr Glucose/Lactulose Combo-BioHealth Kit

This test will give you a combination of both glucose and lactulose testing in the full 3-hour timeframe.

Small Intestinal Bacterial Overgrowth (SIBO) (910-C) 2-Hr Glucose/Lactulose Combo-BioHealth Kit

This test is the same as above, only the timeframe is just the 2 hours.

FoodMarble AIRE2 Device review #foodmarble #LOWfodmap how to use

BTW – you can test instantly for hydrogen and methane and what you might be reacting to with the FoodMarble Aire Device + program.

Use code: GUTSYG at checkout to save 15%

Small Intestinal Bacterial Overgrowth (SIBO) (911-C)- Glucose/Lactulose/Fructose Combo-BioHealth Kit

With this option, you’re getting the full 3-hour test plus a test of all: glucose, lactulose, and fructose.

The Fructose Malabsorption test is a breath test measuring hydrogen and methane production at time intervals after consuming a fructose solution.

If the fructose doesn’t digest normally, gut bacteria will ferment the fructose, forming hydrogen and/or methane.

Hydrogen and methane are not normal products of human digestion.Measuring the amount of hydrogen and methane in breath samples reveals the potential for fructose malabsorption and can help identify a potential cause of gas, bloating and diarrhea after eating food rich in fructose.

Small Intestinal Bacterial Overgrowth 2-Hr Lactulose (SIBO, BOSI)-Genova Kit

You might not know what BOSI stands for.

It’s the same thing as SIBO, essentially: Bacterial Overgrowth of the Small Intestine. This is a 2-hour kit using lactulose only by Genova Diagnostics.

You can learn more about the test and Genova HERE

Small Intestinal Bacterial Overgrowth 3-Hr Lactulose (SIBO, BOSI)-Genova Kit

This is a 3-hour test using lactulose only by Genova Diagnostics.


  1. Lactose and lactulose are not the same things. If, however, you are severely intolerant or allergic to lactose, be sure to work with your doctor prior to choosing the lactulose option(s).
  2. According to the testing site (where all tests are linked above), “With lactulose, there is greater ability to diagnose overgrowth in the distal end of the small intestine, which is thought to be most common. With the glucose challenge, absorption occurs faster so the test more accurately diagnoses proximal overgrowth, which is considered more specific to the bacteria of concern.”
  3. SIBO + BOSI. I told you what each stand for above. All these acronyms. I get it. That’s what I created the Gutsy Glossary HERE.

Ordering Your SIBO Test

You can click any of the links above to order your test now. 

If you prefer to call and place orders for these SIBO tests vs. purchasing online, you can choose that instead. Here are the steps:

  1. Call 800-908-0000 and use code R-AGG.
  2. They will process your order and an online account will automatically be created for you.
  3. You will receive an email letting you know the kit is being mailed to you.  The kit will include instructions for collection, collection containers, and a prepaid Domestic shipping label to ship the specimen to the lab.
  4. An email will be sent advising your results are in and they will be located in the account that was created for you.

Please let me know if you have anymore questions.

Happy to add to the Buyer’s Guide to SIBO Tests if you need it.

If you found the Buyer’s Guide to SIBO Tests valuable, consider:

  1. A Gutsy Girl’s Bible: a 21-day approach to healing the gut
  2. Hydrogen Breath Test at Home
  3. Fructose Structure
Buyer's Guide to SIBO Tests #sibo #fodmap #guthealth



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One Comment

  1. Hi Sarah, I am researching SIBO tests and believe it is very important for me to have a Fructose test also, since my progressive gut issues seemed to begin with Fructose Malapsorption symptoms six years ago. However, the link you provided above only includes two basic SIBO tests now (not all of the options you’ve outlined above). Furthermore, Googling cannot seem to locate an alternative SIBO test that includes Lactulose, Glucose and Fructose. The closest I can find is Lactulose + Lactose. The lactose probably would not be necessary for me, since I do not (yet) struggle with lactose intolerance.

    This is the test I want, but it’s simply not on the site anymore:
    Small Intestinal Bacterial Overgrowth (SIBO) (911-C)- Glucose/Lactulose/Fructose Combo-BioHealth Kit

    Also, any insight into why SIBO tests have become more simplistic, rather than more comprehensive, over time?

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