What is the SIBO Test: How To Prepare & Next Steps

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A SIBO test is a non-invasive hydrogen breath test. It’s the primary diagnostic test for small intestine bacterial overgrowth (SIBO), a complex disorder of the digestive system. SIBO is linked to multiple causes, making diagnosing and treating it difficult. 

SIBO affects millions of people, many are unaware of the disorder. Living with the side effects can decrease your quality of life. The disorder may be triggered by irritable bowel syndrome (IBS), hypothyroidism, and other medical conditions.

SIBO Hydrogen Breath Test

What is a SIBO test? A SIBO Test is a non-invasive hydrogen breath test used to identify changes in the gut microbiome and abnormal growth of bacteria in the small intestine. 

How do you get tested for SIBO? Your healthcare provider can test you for SIBO by giving you a SIBO test that takes approximately 3 hours. Throughout the test, they will measure levels of hydrogen and methane in your breath at regular intervals.

Can I test myself for SIBO? You can test yourself for SIBO, but at-home test kits are prone to contamination or poor implementation. It’s best to receive a breath test in the controlled environment of a doctor’s office to ensure accurate test results are not contaminated.

What to Expect

To begin your breath test, you’ll drink a solution of water and lactulose or glucose substrate. Bacteria in your small intestine love sugar and will produce more gas as they consume it.

Does the SIBO test make you sick? A SIBO test should not make you sick or cause any more discomfort than you usually experience when consuming sugars or carbohydrates.

Lactulose is manufactured sugar that acts as a laxative because our bodies cannot digest it. It contains galactose and fructose. Lactulose differs from lactose, but many SIBO breath tests contain lactose. Talk with your doctor about other options if you have severe lactose intolerance.

Although lactulose breath tests have been standard in the past, glucose breath tests are becoming more popular thanks to better accuracy. Lactulose breath tests can produce more false positives than glucose tests produce false negatives.

Because it is present in so many cases of IBS, breath testing for SIBO is one way we diagnose IBS.

Before the SIBO test

Consult with your doctor about how you can best prepare for your breath test. In general, here’s what you can do to prepare:

  • Plan for 2- and 3-hour tests. The 3-hour breath test is preferred for most patients, especially if they suffer from constipation.
  • Don’t take probiotics or antibiotics for 4 weeks leading up to your breath test. This can skew breath test results.
  • Check with your doctor about taking PPIs (proton-pump inhibitors). We recommend talking to your provider about your use of PPIs, as they can increase your risk of SIBO.
  • Avoid laxatives, bowel purgatives (given for colonoscopies), and fiber supplements the week before your breath test.
  • 24 hours before your test, adhere to a low-residue diet, minimizing sugars and starches.
  • Do NOT eat 12 hours before your test. You can drink water and nothing else.
  • Take all your medications (other than antibiotics, of course) 6 hours or more before your test. Try not to take anything within 6 hours before the breath test.
  • Do NOT smoke 1-2 hours before your test.

During Your Breath Test

When it is time for SIBO breath testing to commence, you’ll follow these steps:

  1. If you’re administering the test at home, make sure the test is not expired.
  2. Doctors may ask you to rinse your mouth out to reduce contamination from your oral microbiome.
  3. Provide a baseline breath sample. This usually begins by blowing up a balloon.
  4. Drink the sugar solution containing the carbohydrates (glucose or lactulose). This will react with your gut bacteria.
  5. Breathe into the breathalyzer, or special glass tubes, that measure how quickly your gut is producing hydrogen and methane gas. Tests may require you to continue giving breath samples every 15-20 minutes.
  6. During the test, you cannot eat, drink, sleep, or exercise vigorously.
  7. Take the time to catch up on magazines or movies during the 2-3 hour test time.

Results and Next Steps

Once the provider has collected your breath samples, test results are usually ready within 2-14 days. Your doctor will discuss the results with you. 

What does it mean if you test positive for SIBO? Testing positive for SIBO means that your hydrogen levels are above 20 ppm from your baseline. If you have positive results, you can discuss treatment options with your provider.

A methane-positive SIBO breath test usually indicates constipation-dominant IBS (IBS-C).

A hydrogen-positive SIBO breath test usually indicates diarrhea-dominant IBS (IBS-D).

What is SIBO?

SIBO is the acronym for small intestine bacterial overgrowth, a gut health disorder of excessive bacterial growth and presence in the small intestine. A majority of IBS patients suffer from SIBO. The most prevalent way to test for SIBO is through a breath test.

According to a cross-sectional study from 2003, 6% of healthy individuals could suffer from SIBO without knowing it. That percentage jumps to 15% for adults above 61 years old.

What are the first signs of SIBO? The first signs may include feeling like you’re bloated or gassy all the time. Some people suffering from SIBO may also experience symptoms such as a lack of appetite, nausea, constipation, or diarrhea.

How do doctors test for SIBO? Doctors typically test for SIBO with a SIBO breath test. They can also do a jejunal aspiration, which is much more invasive and costly.

Symptoms of Small Intestine Bacteria Overgrowth

If you are experiencing symptoms of SIBO, consider a SIBO test to diagnose your condition. 

The symptoms of SIBO may include:

  • Abdominal pain
  • Bloating
  • Cramping
  • Stomach growling
  • Flatulence
  • Constipation or diarrhea
  • Nausea
  • Fat malabsorption
  • Weight loss
  • Fatigue
  • Rash
  • Joint pain
  • Asthma
  • Skin conditions (acne, eczema, rosacea, etc.)
  • Malnutrition


Surgery or disease can cause SIBO when the digestive system slows down, allowing bacteria to colonize your digestive tract. The following medical conditions may cause or contribute to SIBO:

  • Hypothyroidism
  • Cirrhosis of the liver
  • Diabetes
  • Celiac disease
  • Fibromyalgia
  • Parkinson’s disease
  • Scleroderma
  • Small bowel diverticulosis
  • Inflammatory bowel disease (Crohn’s disease or ulcerative colitis)
  • Irritable bowel syndrome

Risks of SIBO

What happens if SIBO is left untreated? If your SIBO is left untreated, dehydration and malnutrition can occur. In severe cases, dehydration and malnutrition can lead to death, though this is rare. 

If you are experiencing digestive health distress and have symptoms of malnutrition such as pale skin, unusual food cravings, or difficulty breathing, contact your healthcare provider immediately.

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More Ways to Diagnose SIBO

  • Small intestine culturing — Many believe culturing your small intestine is the gold standard for SIBO diagnosis. With culturing, however, contamination is possible. This test is also more invasive and expensive.
  • Personal medical history — Talking about your personal medical history helps your doctor understand what the root cause of your SIBO could be.
  • Family medical history — Discussing your family medical history may reveal genetic dispositions towards certain gastrointestinal disorders, such as SIBO.
  • Physical examination — Endoscopies are invasive physical exams that can help diagnose SIBO. 
  • Blood test — A SIBO blood test can detect SIBO caused by food poisoning. These blood tests typically measure antibodies against toxins and nerve proteins. More often, a blood test would simply rule out conditions other than SIBO.
  • Urine test — Urine testing can detect significant bacterial markers, but it’s almost impossible to know the origin of these markers. Urine tests are best used in conjunction with other tests.
  • Stool test — Comprehensive stool testing can help determine the bacterial makeup of your large and small bowels.

Treatments for SIBO

How do you treat SIBO? You can treat it in various ways, depending on the root cause of your SIBO, but its treatment boils down to 3 basic steps (the 3 R’s):

  1. Reduce small intestine bacterial overgrowth
  2. Restore gut motility
  3. Repopulate good bacteria in your large intestine

You can achieve this process of reducing, restoring, and repopulating in several ways.

  • Avoid antibiotics. If you take too many antibiotics, you can develop antibiotic resistance, which comes with its own issues. You may even develop a secondary or worsened infection from the antibiotics themselves. On occasion, antibiotics are necessary, but they should be used only as a last resort.
  • Reduce daily stress whenever possible. Constant stress activates immune responses that, in the long term, harm our bodies. One of many ways that stress can make our immune system turn against us is by triggering SIBO. Cutting out stress may help treat SIBO, and restore normal gut motility.
  • Eat a SIBO diet to treat and prevent SIBO. We recommend the low-FODMAP diet, which is also helpful for managing IBS. This means avoiding honey and ripe bananas for SIBO or IBS.
  • Try a dietary supplement. We recommend incorporating supplements such as oregano oil or garlic extract (because of the allicin).
  • Don’t use probiotics until you are sure the small intestine bacterial overgrowth is addressed. Probiotics help repopulate your large intestine with good bacteria, but they can also worsen small intestine bacterial overgrowth.

There are medications to treat SIBO. Typically, we don’t prescribe pharmaceuticals unless absolutely necessary. Here are a few medications that may treat it:

  • Prokinetics, like prucalopride or naltrexone
  • Antibiotics, like rifaximin or neomycin
  • Antispasmodics, but mainly for patients experiencing diarrhea more often than constipation

SIBO patients typically consume less fiber and less vitamin B2, B6, and B9 than individuals who do not suffer from it. We always recommend consuming plenty of fiber and enough B vitamins to assist in treating and preventing SIBO.

Individuals with active SIBO can find that supplemental fiber exacerbates pain and bloating, so discuss taking supplemental fiber outside your food with your practitioner.

Outlook for SIBO Patients

Many mainstream gastroenterologists and researchers would call SIBO “incurable,” but we disagree! They really mean that we need to address the root causes that have led to bacterial overgrowth. There are multiple treatments that PrimeHealth provides to address the root causes. 

Live in the Denver area and struggling with SIBO symptoms? Get a FREE in-person consultation with a member of our medical staff! Schedule your appointment today.


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