Small Intestinal Bacterial Overgrowth (SIBO): Symptoms, Treatment, & Diagnosis

By Chesney Fowler, MD
Medically reviewed checkmarkMedically reviewed
December 30, 2019

Have you been told that you have small intestinal bacterial overgrowth or, SIBO? It may be the first time you’ve ever heard of the condition, and you might be unsure what it means. In this article, you will learn what SIBO is, how it may be diagnosed, and how to manage your symptoms.

What Is SIBO?

SIBO (pronounced ‘see-boh’) stands for small intestine bacterial overgrowth. SIBO occurs when you have an excess of bacteria in your small intestine. Everyone has several types of naturally-occurring bacteria in their intestines but when the delicate balance of bacteria is disturbed due to overgrowth, you can get uncomfortable SIBO symptoms such as bloating, diarrhea, abdominal pain, constipation, and excess gas. You are at a higher risk of developing SIBO if you are an adult female or if you have a preexisting digestive issue, such as irritable bowel syndrome (IBS).

Check your symptoms and get free personalized health answers

Get Started

Causes of SIBO

A normal small intestine (bowel) contains many different types of bacteria – around 10,000 bacteria per milliliter of fluid, to be precise. Some of these bacteria are beneficial (good) and some are considered pathogenic (bad). The good bacteria protect your body from bad bacteria and candida (yeast) overgrowth. They also help your body absorb nutrients from food and produce vitamins, like folate and vitamin K. Good bacteria also help maintain the normal muscular activity of the small bowel, which produces waves that move intestinal contents–such as food and water–through the gut.

When the small intestine does not move food along fast enough, SIBO can develop. When bowel contents move too slowly, bacteria hang around for too long which gives them the opportunity to multiply excessively. Levels of the good bacteria can fall too low relative to the bad bacteria and the resulting imbalance causes the unpleasant SIBO symptoms you are experiencing like gas, bloating and stomach pain.

The main triggers of SIBO are:

  • Abnormally slow movement of food along the digestive system
  • Lower than normal levels of stomach acid, which may be due to medications (e.g. heartburn medications that decrease stomach acid levels)
  • Recurrent antibiotics that impact ‘good’ bacterial growth
  • Physical abnormalities of the small intestine, which may be due to surgery such as gastric bypass
  • A weakened immune system, such as occurs in AIDS and other medical conditions

SIBO Symptoms

SIBO can cause many uncomfortable digestive issues some of which are similar to those caused by other digestive disorders, e.g. IBS, Crohn’s disease, and lactose intolerance.

SIBO signs and symptoms include:

All of these symptoms can also occur with many other medical conditions so it is important to consult with a doctor who can make the correct diagnosis. Prompt treatment will help you avoid some of the unwanted side-effects of untreated SIBO such as malnutrition, unwanted weight loss or anemia.

How Is SIBO Diagnosed?

SIBO can be hard to diagnose as its symptoms are similar to those of other conditions that affect the stomach and intestines. In order to make a definitive diagnosis your doctor may do the following:

  • Take a medical history: Your doctor will ask about your symptoms and take a full medical history.
  • Examine you: Your doctor may feel your abdomen for signs of excess gas or bloating.
  • SIBO breath test (hydrogen breath test): Your doctor might recommend a SIBO breath test to measure the concentration of hydrogen and methane in your breath. Bacteria produce certain gases when they break down carbohydrates in the gut and the results of this test can inform your doctor if bad bacteria in your small intestines are working in overdrive.
  • Endoscopy: Occasionally, your doctor might consider an endoscopy. This is more invasive than the breath test but may be more accurate to identify bad bacteria in your small intestines. The test is performed by means of an endoscope passed down the back of your throat while you are sedated. A sample of fluid is taken from the small intestine and is cultured and evaluated for the presence of bacteria.
  • Medication trial: Your doctor may prescribe a trial period of taking a SIBO medication such as an antibiotic to re-balance your gut microbiota. If your symptoms resolve quickly after taking the medication, it may be concluded that you had SIBO. However, the best way to make these changes permanent is to make dietary and lifestyle adjustments, such as regular exercise, to keep your gut moving along at a normal pace.

SIBO Treatment Options

The first priority in the treatment of SIBO is to get your gut bacteria back into balance to ease your symptoms and help your body better absorb nutrients from your food. Your doctor may recommend some or all of the following treatments:

  • SIBO dietary modifications: Your doctor may put you in touch with a nutritionist specialized in treating SIBO who can advise you on some dietary interventions that could ease your symptoms.
  • SIBO treatment antibiotics: Antibiotics can stabilize the gut microbiota by reducing the number of harmful intestinal bacteria. As always, antibiotics are not without side effects and risks. Overuse of antibiotics can increase your risk of certain types of infections such as C. difficile and candida (yeast). The specific treatment you are offered will depend on the results of the breath test you took. Antibiotics such as rifaximin may be recommended.
  • Nutrient therapy: If you become malnourished or dehydrated due to SIBO, your doctor may order fluids and certain nutrients to be delivered through an intravenous (IV) drip.
  • Relevant medical treatments: If you have an underlying medical condition, such as celiac disease or diabetes, that might have contributed to SIBO, your doctor will recommend suitable treatments for these conditions.
  • SIBO surgery: In very rare cases, SIBO can be caused by a structural problem, such as a stricture, that slows down your gut transit time. If this is the cause of your SIBO, your doctor may recommend surgery.
  • SIBO herbal treatments: Some promising results have been obtained from treating SIBO with mixed herbal therapies. Keep in mind, herbs and supplements can interact with other medications that you take.

SIBO Prevention and Care: What You Can Do at Home

If your SIBO is not due to an illness or a structural abnormality, you may be able to treat or manage your SIBO symptoms by making the following dietary changes:

  • Cut out sugary foods and drinks, including alcohol
  • Keep a food diary and notice which foods make your symptoms worse, then take steps to eliminate them
  • Avoid taking fiber supplements if they contribute to bloating and gas
  • Avoid taking liquid medications (such as cough syrup) that contain sugar alcohols
  • Try a low-FODMAP diet (FODMAPs are a type of carbohydrate that can cause irritation in some people).
  • Take prebiotics or probiotics, either as a supplement or in your diet

If you suffer from any of the following medical conditions, you are more likely to develop SIBO:

Other risk factors for SIBO include:

  • Being of older age
  • Being female
  • Having had previous bowel surgery
  • Long-term use of proton pump inhibitors (PPIs)
  • Having recently completed a course of antibiotics or having had multiple courses of antibiotics
  • Alcohol consumption, even if it is moderate
  • Having lower than normal levels of stomach acid
  • Having diabetes mellitus (either type I and type II)
  • Suffering from an organ system dysfunction, such as liver cirrhosis, chronic pancreatitis, or renal failure
  • Taking oral contraceptive pills (OCPs)
  • Structural abnormalities such as diverticulosis (pouches in the wall of the intestine), scar tissue from radiation or abdominal surgery, a buildup of a protein called amyloid in your small intestine or short bowel syndrome
  • Having a GI tract blockage
  • Taking narcotics

Check your symptoms and get free personalized health answers

Get Started

Complications of SIBO

Having an abnormally large population of harmful bacteria in the small intestine can impact the body in other ways. Bacterial overgrowth makes it harder for the body to absorb nutrients and carbohydrates from food which can lead to vitamin deficiencies and excessive gas.

Other complications that you may experience alongside SIBO are:

When to See a Doctor

If you are experiencing SIBO-like symptoms that have not gone away or responded to any treatments you have tried, speak to your doctor. SIBO can be unpleasant but there is no reason to suffer for long periods when your doctor can advise you about treatments that will restore the balance of your gut bacteria and relieve your symptoms.

How K Health Can Help You

K Health can help you quickly determine whether you may have SIBO and can connect you to a doctor instantly. Our doctors are available to help you learn how to relieve your symptoms and what you can do to help prevent them in the future.

K Health articles are all written and reviewed by MDs, PhDs, NPs, or PharmDs and are for informational purposes only. This information does not constitute and should not be relied on for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment.

Chesney Fowler, MD

Dr. Fowler is an emergency medicine physician and received her MD from George Washington University. She completed her residency in emergency medicine at Christiana Care Health System. In addition to her work at K Health, Dr. Fowler is a practicing emergency medicine physician in Washington, DC.