Small Intestinal Bacterial Overgrowth (SIBO) is a condition where bacteria that normally live in the large intestine migrate into the small intestine, where they don’t belong. This imbalance can interfere with digestion, absorption, and overall gut health—leading to a wide variety of symptoms that often overlap with other digestive concerns.
At Sun Valley Natural Medicine, we see SIBO as one piece of a larger health picture. By understanding the different types, symptoms, and testing options, you can better appreciate how personalized treatment is essential.
Types of SIBO
Not all SIBO looks the same. Depending on which gases the bacteria produce, SIBO can present differently in each person.
Hydrogen-dominant SIBO
Caused by bacteria that produce hydrogen gas.
Often associated with diarrhea, bloating, and abdominal discomfort.
Methane-dominant SIBO (sometimes called Intestinal Methanogen Overgrowth, or IMO)
Caused by archaea (not technically bacteria) that produce methane gas.
Frequently linked with constipation, bloating, and slower gut motility.
Hydrogen sulfide-dominant SIBO
Involves bacteria that produce hydrogen sulfide gas.
Can present with diarrhea, bloating, abdominal pain, and sometimes a sulfur-like odor to gas.
Some people may have a mixed picture—with elevations in more than one type of gas.
Common Symptoms
The type of SIBO often influences which symptoms are most prominent, but overlap is common.
Hydrogen-dominant: Loose stools, urgency, bloating, cramping, fatigue.
Methane-dominant: Constipation, bloating, abdominal distension, slow transit time.
Hydrogen sulfide-dominant: Diarrhea, foul-smelling gas, abdominal pain, brain fog.
Beyond digestive symptoms, SIBO may also contribute to nutrient deficiencies (such as B12, iron, or fat-soluble vitamins), skin conditions, joint pain, and mood changes.
Diagnostic Approaches
Because symptoms alone cannot confirm SIBO, testing plays an important role.
Breath testing
The most common and non-invasive way to test for SIBO.
Patients drink a sugar solution (like lactulose or glucose), and breath samples are collected every 15–20 minutes to measure hydrogen, methane, and sometimes hydrogen sulfide gases.
The TrioSmart breath test is one of the newer options and measures all three gases—hydrogen, methane, and hydrogen sulfide—in a single test.
Other approaches
Small bowel aspirate and culture is considered the “gold standard” but is invasive and rarely used outside of research or specialty centers.
Symptom assessment and therapeutic trials can provide clinical insight, though they’re less precise than breath testing.
At Sun Valley Natural Medicine, we typically recommend breath testing, as it balances accuracy, accessibility, and patient comfort.
Treatment Considerations
Treatment for SIBO is never one-size-fits-all. Depending on the type and severity, approaches may include:
Dietary strategies – Temporary use of specific diets (such as low-FODMAP or SIBO-specific diets) to reduce fermentable foods that feed bacteria.
Herbal antimicrobials or antibiotics – To reduce bacterial overgrowth. Choice depends on gas type and patient tolerance.
Prokinetics – Support gut motility, especially after treatment, to reduce recurrence.
Nutrient support – Address deficiencies (like B12 or iron) that often accompany SIBO.
Underlying root causes – Correct issues such as low stomach acid, sluggish motility, chronic stress, or structural concerns that predispose to SIBO.
Because recurrence is common, treatment usually involves not just clearing the overgrowth but also rebuilding long-term digestive health.
Final Thoughts
SIBO is a complex condition that looks different in every person. Whether you experience diarrhea, constipation, or a mix of both, your symptoms and test results help guide the right approach.
At Sun Valley Natural Medicine, we emphasize individualized care—because no two SIBO cases are exactly the same. With thoughtful testing, targeted treatment, and ongoing support, it’s possible to restore balance and improve both digestive and overall health.