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Small Intestinal Bacterial Overgrowth (SIBO)

Small intestinal bacterial overgrowth (SIBO) occurs when there are excess bacteria in the small intestine. SIBO often happens because of lack of movement of the small intestine.

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SIBO: Why choose Johns Hopkins?

  • Our specialists treat a high number of patients with mild to severe SIBO. We have the experience needed to understand the fine points of the condition and provide the right treatment.
  • The volume of patients we treat means we can study SIBO and improve treatment success. Our division also participates in clinical trials.
  • Our team has specialty training in gastrointestinal diseases. You’ll receive focused treatment and specialized care for your condition.
  • We work with other specialists to manage conditions that occur along with SIBO. For example, if you have scleroderma or diabetes, you may also develop SIBO. Our team works with subspecialists who treat those conditions to ensure seamless care.
  • Our team includes a nutritionist who specializes in helping patients with motility diseases. The nutritionist, along with a registered nurse, can help you change your dietary habits and see improvement in your condition. You have fast access to the team through My Chart.

SIBO Symptoms

SIBO is an abnormal number of bacteria in the small intestine that can lead to:

  • bloating and increased passing of gas (flatulence)
  • diarrhea or constipation
  • abdominal pain
  • nausea
  • fatigue

In more extreme cases, the small intestine may not be able to absorb nutrients. In these situations, you may also experience weight loss and anemia (iron deficiency).

SIBO Treatment Options

Our specialists understand that there are different levels and types of SIBO. These distinctions matter when determining the most appropriate treatment. Depending on the extent of your condition, treatment may vary. We deliver customized treatment for:

  • hydrogen-predominant SIBO: The primary treatment is the antibiotic rifaximin.
  • methane-predominant SIBO: This type of SIBO is harder to treat, and it may take longer to respond to treatment. We use rifaximin plus neomycin for these cases.
  • recurrent SIBO: We closely monitor you for a recurrence of SIBO. If it happens, you will benefit from our experience treating the disease. We have experience with formulations of antimicrobial herbs, which can be used to treat recurrences and as an alternative for initial treatment of hydrogen- or methane-predominant SIBO.
    As part of your treatment, we recommend following a FODMAP (low fermentable oligosaccharides, disaccharides, monosaccharides and polyols) diet and consulting with a nutritionist.

What are SIBO risk factors?

Structural or anatomic abnormalities may affect normal movement of the small intestine (motility). Stasis, or lack of movement, can lead to bacterial imbalance. This can occur if you:

  • Have diverticulosis — tiny bulging pouches (diverticula) in the small intestine
  • Had surgery that changed the small intestine’s structure, such as Roux-en-Y gastric bypass surgery, or surgery on the right colon with removal of the ileocecal valve, or surgery on the last part of the small bowel.
  • Have adhesions (scar tissue) that developed after radiation therapy or after multiple abdominal surgeries
  • Have amyloidosis (a buildup of amyloid protein deposits) — deposits can accumulate in the small intestine and change its structure

Use of certain medications could be linked to SIBO. These include:

  • Narcotic medications
  • Anti-spasm medications for irritable bowel syndrome (IBS), such as hyoscyamine or dicyclomine
  • Long-term use of proton pump inhibitors (PPIs) — medications that decrease acid in the stomach to control heartburn
  • Frequent use of antibiotics, which may alter the bacteria in the small bowel

Chronic systemic conditions can cause motility issues. If you have these conditions, you may be at a higher risk for SIBO:

Having a lowered immune system. This includes those who have:

Our SIBO Diagnostic Procedures

Our gastroenterologists (doctors who specialize in the digestive system) diagnose SIBO with a lactulose breath test. For the test, you will swallow a drink containing the sugar lactulose. Next, you will breathe into a balloon approximately every 15 minutes over the course of three hours. Each time, we remove the breath sample from the balloon and test it. SIBO may be present if your breath sample contains hydrogen or methane shortly after drinking the solution.

We provide the SIBO breath test at our clinics at Green Spring Station and in Columbia, Maryland.

Our Team of SIBO Specialists

Our specialists have extra training in gastrointestinal diseases. That skill, combined with our experience treating SIBO, means we can deliver the highest level of care and the most appropriate treatment.

Kathleen Johnson

Kathleen Johnson, M.A.


Our SIBO Research

Our team is actively involved in understanding SIBO, and our division participates in clinical trials to learn more.

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