Small Intestinal Bacterial Overgrowth (SIBO)

What is small intestine bacterial overgrowth?

SIBO means you have an excess of gut bacteria in your small intestine. This bacteria is supposed to be present in other parts of your digestive system, such as the colon. Though bacteria is necessary to digest food properly, it’s important that the bacteria, and your digestive system in general, are balanced and work together effectively.

Signs and symptoms of SIBO include:

  • Bloating and excess gas
  • Change in bowel habits (diarrhea or constipation)
  • Abdominal pain that’s worse after eating
  • Nausea and cramping
  • Indigestion

In addition to these symptoms, severe cases of SIBO can interfere with your body’s ability to absorb nutrients. Your small intestine may not be able to perform its usual role in digestion. This can happen as a result of the bacteria itself consuming the nutrients, or from the bacteria causing damage to your small intestine.

Is SIBO related to irritable bowel syndrome (IBS)?

SIBO shares many symptoms with IBS, including bloating, abdominal pain, diarrhea, and constipation. Though the exact relationship between SIBO and IBS is unknown, many doctors believe that SIBO is the root cause of IBS for a subset of patients.
Though this may sound confusing, keep in mind that IBS is a collection of symptoms that can result from many different factors. Doctors often arrive at a diagnosis of IBS after ruling out other conditions, and there’s no definitive test for IBS.
If you’ve been diagnosed with IBS and haven’t responded to dietary changes, it’s possible that your symptoms result from bacterial overgrowth, and not from food sensitivities. If you have SIBO, a treatment approach that directly targets the bacteria in your small intestine may relieve some or all of your IBS symptoms.

How is SIBO diagnosed and treated?

If you have the symptoms of SIBO, the physician may perform a breath test. This is a noninvasive test that involves breathing into a tube before and after drinking a sugar solution. If you have SIBO, the excess bacteria may release hydrogen and methane, which are then detectable in your breath.
The primary treatment for SIBO is an antibiotic called XifaxanⓇ that reduces the overgrowth of bacteria in your small intestine. Xifaxan is effective and well-tolerated in most people, but your SIBO may return, requiring multiple courses of antibiotics to manage it.
The physician also look at potential underlying causes of your SIBO. Sometimes, SIBO results from another condition, such as gastroparesis or celiac disease, from structural problems with your digestive system, or from the side effects of medication.