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What is Small Intestinal Bacterial Overgrowth (SIBO)?

Small Intestinal Bacterial Overgrowth (SIBO)

Small intestinal bacterial overgrowth (SIBO) is a condition characterized by an abnormal increase of bacteria in the small intestine that may be associated with abdominal pain, malnutrition, or other symptoms. In most cases, these bacteria do not normally reside in the small intestine but arrive from other parts of the gut.

Causes of Small Intestinal Bacterial Overgrowth

Small intestinal bacterial overgrowth (SIBO) occurs when food moves slowly through the digestive system, promoting the growth of bacteria, and in turn diarrhea and malnutrition. It may be associated with

  • A history of abdominal surgery (Scar tissue)
  • Low levels of stomach acid
  • Structural abnormalities of the small intestine such as a loop or fistula
  • Injury to the small intestine
  • Scar tissue in or around the small intestine
  • Blockage of the GI tract
  • Immune deficiencies
  • Radiation therapy
  • Scleroderma
  • Irritable bowel syndrome
  • Crohn’s disease
  • Ulcerative colitis
  • Certain medications

Symptoms of Small Intestinal Bacterial Overgrowth

Symptoms of small intestinal bacterial overgrowth include:

  • Abdominal pain
  • Diarrhea
  • Bloating
  • Excess gas (flatulence)
  • Loss of appetite
  • Nausea
  • Vomiting
  • Malnutrition
  • Weight loss
  • Weak bones

Diagnosis of Small Intestinal Bacterial Overgrowth

Your doctor will review your medical history and symptoms and perform a physical examination. The following diagnostic tests may be ordered:

  • Lactose breath test: Your doctor will give you a sugar solution to drink. You will be then instructed to breathe out every 15-20 minutes in a bag for 3 hours as the solution gets digested. This test helps to detect high levels of methane and hydrogen which are released by bacteria as they digest the sugar solution.
  • Intestinal aspiration: This study uses an endoscope - a thin, flexible tube with a camera and light source - that is inserted through your esophagus and stomach into your intestine where a sample of intestinal fluid is collected. The sample is evaluated in the laboratory for bacterial growth.
  • Blood tests: To look for vitamin deficiency due to malnutrition
  • Stool tests: To determine if fat has been absorbed properly
  • Imaging tests: Imaging tests such as X-rays, CT scans, and an MRI may be conducted to identify abnormalities of the digestive tract.

Treatment for Small Intestinal Bacterial Overgrowth (SIBO)

Treatment for small intestinal bacterial overgrowth is mainly based on its root cause. Common therapeutic methods include:

  • Medications: Your doctor will prescribe antibiotic medications to reduce the growth of bacteria. You may need a long course of antibiotics and various types.
  • Diet: Your doctor will recommend a nutritional and balanced diet to eliminate deficiencies. In cases of severe malnutrition, IV therapy may be recommended. Fiber supplements should be avoided.
  • Lactose-free diet: You should follow a lactose-free diet if your damaged intestine loses its ability to digest lactose.
  • Surgery: Surgery may be recommended to treat structural abnormalities such as a loop or fistula.


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Dr. Gyawali is exclusively available at

Mubadala Health – Jumeirah, Dubai

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Jumeirah Beach Rd Jumeirah 3
Dubai, UAE

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I was referred to Dr Gyawali for a manometry test. He carefully studied my medical history. and realised that my previous doctor had repeatedly missed a significant diagnosis. He immediately referred me on to the necessary specialists for urgent treatment. I cannot thank him enough..

Patient at Queen's Hospital

29th February 2020