Over the past two years, I have received a growing number of inquiries about treating Hydrogen Sulfide (H2S) SIBO. These questions come from patients who have struggled with recurring SIBO for years and, through their own research, have discovered that a newly recognized gas may be driving their ongoing symptoms.
What is H2S SIBO?
Small Intestine Bacterial Overgrowth (SIBO) has traditionally been diagnosed using a lactulose breath test that measures overproduction of Hydrogen (H2) and Methane (CH4). H2S has been suspected as a contributing factor for some time, but its implications for health have remained poorly understood – and a commercially available test did not exist until seven years ago.
Gas is a natural byproduct of metabolism. All living organisms produce it. Plants release oxygen, animals exhale carbon dioxide (CO2), and H2S is produced by humans, bacteria, and yeasts alike.
In moderate amounts, H2S actually benefits the body: it is anti-inflammatory and helps protect and repair the lining of the gastrointestinal tract.
In excess, however, H2S becomes toxic, particularly to the nervous system. It can damage the mitochondria, the energy-producing centers of our cells, and suppress immune function. Yet two critical questions remain: how much H2S is too much, and how can it be accurately measured outside a research setting?
These unresolved questions have placed the only commercially available test under considerable scrutiny. As clinicians, we must always interpret test results within the broader context of a patient’s symptoms.
So what symptoms might H2S SIBO actually cause?
Our understanding of H2S SIBO’s symptom profile is still evolving.
The most commonly observed symptoms include:
- diarrhea
- bowel urgency
- abdominal pain
- heartburn
- and visceral hypersensitivity
Other possible symptoms are:
- constipation
- bladder irritation or interstitial cystitis-like symptoms
- body pain
- numbness and tingling in the extremities
- and histamine intolerance
Notably, these symptoms often worsen with the consumption of sulfur-rich foods, such as wine, dried fruits, processed meats, eggs, dairy, cruciferous vegetables, onions, and garlic.
How is H2S SIBO Diagnosed?
Diagnosing H2S SIBO involves a two-hour breath test performed at home. The patient drinks lactulose, a sugary laxative that humans cannot digest, which passes to the lower small intestine where bacteria ferment it and produce gas.
An H2S reading above 3 at any point during the test is considered positive, suggesting that H2S-producing bacteria or yeasts are likely responsible for the patient’s symptoms.
A reading below 2 makes this less likely. TrioSmart by Gemelli Biotech is currently the only commercially available test that measures all three gases: H2, CH4, and H2S.
What Does H2S SIBO Treatment Look Like?
Treatment for H2S SIBO falls into three categories: elemental diet, antibiotics, and herbal antimicrobials.
The elemental diet involves drinking a pre-digested nutrient formula that is absorbed rapidly in the upper third of the small intestine, effectively starving the bacteria in the lower small intestine.
Antibiotic options include Rifaximin, Neomycin, Amoxicillin-clavulanate, Trimethoprim/sulfamethoxazole, and Nitazoxanide.
Herbal antimicrobial options include bismuth compounds, oregano, uva ursi, pomegranate, silver, prebiotics, probiotics, molybdenum, and butyrate, among others.
While we do not yet have sufficient data to determine which approach is most effective, we have seen positive outcomes with each of the options listed above. Like intestinal methanogen overgrowth (IMO), H2S SIBO tends to be more difficult to treat, and an additional anti-biofilm protocol is often required.
If you suspect you may have H2S SIBO, it is important to consult a trained provider rather than attempting to treat the condition on your own. Many other health conditions can present similarly, and interpreting breath test results is rarely straightforward. An inaccurate diagnosis can lead to delayed, ineffective, or unnecessary treatment.
Please reach out to the providers at Naturopathic Family Health for proper evaluation and guidance. Feel free to schedule a complimentary 10-minute consultation to learn more about our individualized approaches.
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Dr. Sherry Su, ND, FABNG
Naturopathic Doctor San Jose
408-356-1364
Dr. Sherry Su is a licensed naturopathic doctor specializing in gastrointestinal disorders, women’s health, thyroid and adrenal imbalances, and anxiety. She earned her degree from Bastyr University and holds the prestigious FABNG certification for advanced expertise in evidence-based naturopathic gastrointestinal care. With a compassionate, integrative approach, Dr. Su uses minimally invasive therapies to help patients reclaim their health and well-being. She is passionate about empowering patients with sustainable lifestyle changes and personalized care.
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