Does your gut need a reset?

Yes, I'm Ready

Do you want to start feeling better?

Yes, Where Do I Start?

Do you want to start feeling better?

Yes, Where Do I Start?

The SIBO Scenario a Breath Test Can’t Detect

If you have IBS and test negative for SIBO, does that mean you’re in the clear? Not exactly. There is another type of SIBO that a traditional breath test does not diagnose.

If you need help with IBS and SIBO, click here


The SIBO Scenario a Breath Test Can’t Detect

IBS stands for irritable bowel syndrome, which includes a variety of symptoms such as gas, bloating, altered bowel function, and abdominal pain. SIBO (small intestinal bacterial overgrowth) is now recognized as the primary underlying cause of IBS.

More and more people and practitioners are becoming aware of SIBO and testing for SIBO. SIBO is commonly diagnosed using a breath test that measures the levels of hydrogen and methane in the breath. If either hydrogen or methane is above a certain level, then you test positive for SIBO.

Treatment is then recommended in the form of antibiotics, herbal antimicrobials, or an elemental diet.

While we’ve made much advancement in diagnosing and treating SIBO and IBS, there is one type of SIBO that may still get missed.

Hydrogen sulfide is a different type of marker for SIBO that is often overlooked. The standard breath test only tests for hydrogen and methane. However, there is a certain type of bacteria known as sulfate-reducing bacteria (SRB) that produces hydrogen sulfide (H2S).

Therefore, you may have IBS symptoms, undergo a breath test, and have it come back negative. Does this confirm you don’t have SIBO? Not necessarily. While you may not have hydrogen or methane SIBO, you may have hydrogen sulfide SIBO.

The unique symptom of hydrogen sulfide production is a “rotten egg” odor to belching or flatulence.

Hydrogen sulfide SIBO may be suspected when the typical symptoms are present but the breath test shows “flat-line” hydrogen and methane levels.

At this point, there is a research group in India that has created a breath test for H2S, but it’s not readily available. There is also a urine test, but it hasn’t been validated.

In this case, if you have IBS symptoms, it may be beneficial to undergo treatment for SIBO even if your breath test is negative. There is a good chance you may have hydrogen sulfide SIBO, but we don’t have a good way to test for it yet.

If you have a negative breath test, and you decide to treat SIBO, then start with a more mild treatment option, such as a low FODMAP diet, probiotics, herbal antimicrobials, or an elemental diet. If hydrogen sulfide SIBO is suspected, it’s been indicated to use the same treatment methods as those used for methanogen overgrowth.

We recommend holding off on prescription antibiotics initially since there is not a diagnostic test to confirm if H2S overgrowth is present.

In the future, we hope to have a validated hydrogen sulfide breath test available to allow us to more accurately diagnose and treat SIBO.

To learn more about H2S SIBO, check out our video here.


If you need help with IBS and SIBO, click here

What do you think? I would like to hear your thoughts or experience with this.

Dr. Ruscio is your leading functional and integrative doctor specializing in gut related disorders such as SIBO, leaky gut, Celiac, IBS and in thyroid disorders such as hypothyroid and hyperthyroid. For more information on how to become a patient, please contact our office. Serving the San Francisco bay area and distance patients via phone and Skype.


I care about answering your questions and sharing my knowledge with you. Leave a comment or connect with me on social media asking any health question you may have and I just might incorporate it into our next listener questions podcast episode just for you!