Small intestinal bacterial overgrowth (SIBO) is a serious condition affecting the small intestine. It occurs when bacteria that normally grow in other parts of the gut start growing in the small intestine. That causes pain and diarrhea. It can also lead to malnutrition as the bacteria start to use up the body’s nutrients.

Read on to learn more about SIBO.

SIBO symptoms mainly affect the gut. They may include:

  • pain in the stomach, especially after eating
  • bloating
  • cramps
  • diarrhea
  • constipation
  • indigestion
  • regular feeling of fullness
  • gas

You may also experience weight loss.

SIBO is not yet well understood. It can occur when:

  • your small bowel has anatomic abnormalities
  • the pH changes in your small bowel
  • your immune system isn't working properly
  • the muscular activity of the small intestine malfunctions, which means that food and bacteria aren’t removed from the organ

SIBO is associated with various conditions, such as:

Read more: What’s causing abdominal pain and diarrhea? »

Having a chronic condition or surgery that affects the gastrointestinal (GI) tract can put you at risk of SIBO. Certain diseases and chronic conditions can also increase your risk, including:

  • Crohn’s disease
  • diabetes
  • scleroderma
  • HIV
  • Parkinson’s disease
  • hypothyroidism
  • medications that slow down the gut, such as narcotics

See your doctor if you have any of the symptoms of SIBO. Your doctor will ask about your symptoms and medical history. They’ll also do a physical examination, which may include palpating, or gently feeling, your abdomen. They may also order blood, fecal, or other tests.

Breath test

A breath test is a common test for diagnosing SIBO. Excess bacteria in the small intestine can lead to the release of the gases hydrogen and methane, which can be identified through a breath test. This test is noninvasive and can be performed at home or in a doctor’s office.

You’ll need to fast overnight before having a breath test. During the test, you’ll breathe into a tube. You’ll then drink a special sweet drink provided by your doctor. You’ll breathe into a series of additional tubes at regular intervals for 2 to 3 hours after consuming the drink.

Further testing

If the breath test isn't conclusive or SIBO treatments aren’t working, your doctor may need to sample the fluid from your small bowel to see what bacteria is growing there.

SIBO can be treated with a combination of antibiotics and diet changes.

Antibiotics

First, you need to get the bacteria under control. This is usually done with antibiotics, such as ciprofloxacin, metronidazole (Flagyl) or rifaximin (Xifaxan). You may also need intravenous (IV) therapy for nutrition and fluids if your condition has led to malnutrition or dehydration.

Antibiotics may decrease the number of bacteria in the small intestine, but they won’t address the underlying issue that caused the problem in the first place. If your doctor determines that your SIBO is due to an underlying condition, you’ll also need to begin treatment for that condition. Diet changes may also help.

Diet and SIBO

There’s no evidence to prove that a certain diet causes SIBO, but many people with SIBO have found relief after following a special diet. Work with your doctor before making any changes to your diet.

You may only need to make small adjustments:

  • Eat a balanced, nutritious diet.
  • Eat smaller meals more frequently to avoid having too much food sitting in your stomach.
  • Avoid gluten products if you have celiac disease.

Your doctor may also recommend trying an elemental diet. This diet replaces food and drinks with certain liquid formulas for a specified amount of time. In one small-scale , 80 percent of participants with SIBO had a normal breath test result after following an elemental diet for 15 days. The researchers concluded that an elemental diet may be highly effective at managing this condition. More research is needed, however. Work with your doctor before starting this diet, and follow their instructions.

Can probiotics be used to treat SIBO?

Taking probiotics could help return the bacteria in your gut to normal. A found that probiotic treatment could be more effective at treating SIBO than antibiotics. However, a from 2016 found that evidence for the effects of probiotics in treating SIBO was inconclusive. Your best option is to follow your doctor’s advice.

SIBO usually occurs because of an underlying condition. If you have a chronic condition, such as Crohn’s disease or celiac disease, work with your doctor to develop a long-term treatment plan. SIBO is treatable, but it may recur. It can also lead to dehydration and malnutrition when it’s left untreated. Contact your doctor if you suspect you have SIBO so that you can start treatment right away.