Small Intestine Bacterial Overgrowth (SIBO)

What is Small Intestine Bacterial Overgrowth (SIBO)?

Small Intestine Bacterial Overgrowth (SIBO) is an unexpected surge in bacteria in the small intestine. The excess bacteria can either be bacteria normally found in the small intestine or bacteria not normally found there. SIBO is also referred to as Small Intestinal Bacterial Overgrowth and Blind Loop Syndrome.


The symptoms of Small Intestine Bacterial Overgrowth (SIBO) are similar to the symptoms of other digestive issues such as lactose intolerance and Irritable Bowel Syndrome. Since SIBO occurs in the small intestine, the SIBO symptoms affect the digestive system.

The symptoms of SIBO include:

  • Stomach pain/discomfort
  • Diarrhea
  • Constipation
  • Bloating
  • Nausea
  • Fatigue
  • Loss of appetite
  • Flatulence (gas)
  • Weight loss
  • Weakness
  • Cramping pain
  • Discomfort after eating


Small Intestine Bacterial Overgrowth is most commonly caused by food trapped or moving slow through the small intestine. This lingering food is an ideal breeding ground for bacteria. The bacteria often interrupt the absorption of nutrients into the body and can yield harmful toxins.

Other SIBO causes include:

  • Tissue in your small intestine: Scar tissue on the small bowel or pockets of tissue that stick out through the wall of the small intestine can block the fast passage of food through the small intestine.
  • Abdominal surgery complications: Sometimes complications during surgery on the abdomen create the conditions for SIBO.
  • Other medical conditions: Other medical conditions can reduce the speed at which food moves through the small intestine. A few of these medical conditions are radiation enteritis, scleroderma, Crohn's disease, celiac disease, and diabetes.

Why Does SIBO Occur in Post-Bariatric Surgery Patients?

Post-Bariatric Surgery Patients might experience SIBO. During bariatric surgery, doctors divide the small intestine into two pouches. One of these pouches is a dead end, known as a blind loop, where bacteria can collect. This can lead to Small Intestine Bacterial Overgrowth.


We recommend that you schedule an appointment with your doctor if you have any of the symptoms of Small Intestine Bacterial Overgrowth. During the appointment, your doctor will conduct a routine physical exam, ask about your symptoms, and explore your medical history.

The physical exam may include your doctor gently applying pressure to your abdomen. Your doctor may also order additional tests such as breath, blood, stool, or other tests (like X-rays) that will help them with a SIBO diagnosis. The prognosis for SIBO is optimistic. There are treatments for SIBO and sometimes changing lifestyle habits is enough to resolve the condition.

Breath test

A SIBO breath test is a noninvasive test that can be administered in a doctor’s office or at home. The breath test can detect high levels of hydrogen or methane, two gases released by surplus bacteria in the small intestine. For this test, your doctor will ask you to fast the night before, to consume a sweet drink and to breathe into a series of tubes or medical balloons at intervals for 2-3 hours.

Blood test

Your doctor will take a small sample of your blood to test for a lack of nutrients or anemia. Anemia is when your blood lacks enough red blood cells to convey oxygen to your body, which often results in fatigue.

Stool sample

Your doctor will collect a stool sample to test for your body’s absorption of fat. A low rate of absorption can suggest SIBO. Excess bacteria in the small intestine can reduce the normal absorption rate of nutrients into your body.


Treatment for Small Intestine Bacterial Overgrowth usually involves treating the underlying condition causing SIBO. Treatment can include a regimen of antibiotics, surgical repair, and nutritional support.


Antibiotics are generally the first step of SIBO treatment. Your doctor will prescribe medication that you may need to take long-term to reduce and manage bacteria in your small intestine. Medication can quickly reduce bacteria; however, bacteria can multiply again if a patient stops taking their SIBO antibiotics.

Surgical Repair

Surgery is used to repair the structural issues with the small intestine, such as a pouch of tissue collecting bacteria or tissue blocking the passage of food. Surgery can be combined with antibiotics and nutritional support.

Nutritional Support

Your doctor may recommend nutritional supplements to correct nutritional deficiencies as a result of SIBO. Your doctor may also suggest a lactose-free diet because individuals with damaged small intestines sometimes lose the ability to properly digest lactose (sugar in milk and other dairy products). Managing your nutrition can reduce intestinal stress, improve weight gain, and resolve nutritional shortages common with Small Intestine Bacterial Overgrowth.


Small Intestine Bacterial Overgrowth may produce complications across your entire body. For example, bacterial overgrowth can reduce the body’s ability to absorb fats and carbohydrates in foods.

Other SIBO complications can include:

  • Joint pain
  • Constipation
  • Reduced brain function
  • Dehydration
  • Malnutrition
  • Leaky gut (gas, bloating, cramps)

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