By Venturis Clinic, Oklahoma City · Updated November 2026

SIBO, or small intestinal bacterial overgrowth, means there are more bacteria in the small intestine than there should be, and the usual way to test for it is a breath test done at home over two to three hours. At Venturis Clinic in Oklahoma City, SIBO testing is part of a wider gut workup that starts with a listening consult and a Good Faith Exam, with all care performed by licensed medical staff under our medical director.

This page explains what SIBO is, the signs, how breath testing works and where it falls short, and what a care plan can involve. It is not a diagnosis. SIBO is one of several things we look for when someone has IBS-type symptoms; see our main IBS doctor in Oklahoma City page for the bigger picture.

What is SIBO?

Most of the bacteria in the gut live in the large intestine. The small intestine normally has far fewer, kept in check by stomach acid, the steady forward movement of the gut, and the valve between the small and large intestine. When one of those defenses fails, bacteria can build up in the small intestine. They ferment food early, which produces gas and can affect how nutrients are absorbed.

When the overgrowth produces mostly methane rather than hydrogen, it is now often called intestinal methanogen overgrowth (IMO). Methane is linked more with constipation, while hydrogen is linked more with diarrhea, though many people have a mix.

Common signs of SIBO

Bloating that builds through the day, often worse after meals
Excess gas and belching
Diarrhea, constipation or both
Abdominal pain or discomfort
Feeling full quickly
In some people, low vitamin B12, fatigue or unplanned weight loss

These symptoms overlap heavily with IBS, food intolerances and other gut conditions, so they cannot confirm SIBO on their own.

See a doctor promptly if you have

Blood in your stool, black stools, unexplained weight loss, a fever, vomiting that will not stop, trouble swallowing, or new symptoms after age 45. These need a standard medical evaluation first, and we will help you get that done.

Who is more likely to get SIBO

People whose gut moves slowly, including some with diabetes, thyroid problems or dysautonomia
People who have had abdominal surgery
Long-term users of acid-reducing medications
People who developed gut symptoms after a stomach infection or food poisoning
Some people with long COVID gut symptoms

How SIBO breath testing works

A breath test measures hydrogen and methane gas, which human cells do not make; bacteria do. You follow a simple diet the day before, fast overnight, then drink a sugar solution (usually lactulose or glucose) and breathe into collection tubes every 15 to 20 minutes for two to three hours. If bacteria in the small intestine ferment the sugar early, gas levels rise sooner than expected.

Before testing, you may be asked to stop antibiotics for several weeks and to pause certain supplements, laxatives or medications that affect the gut. We go through the preparation with you, because poor prep is a common reason for a misleading result.

What a breath test can and cannot tell you

Breath testing is useful but imperfect. Results can come back positive in people whose symptoms have another cause, and negative in people who still have a problem. Fast gut transit can make a result look positive; recent antibiotics or poor prep can make it look negative. That is why we read a breath test alongside your history, exam and other results, not on its own. Depending on your symptoms, we may also look at stool testing, nutrient levels, thyroid function or celiac screening. Our lab testing page lists what we use.

How Venturis works up suspected SIBO

Listening consult. When symptoms began, what helps and what makes them worse, diet, medications, past infections and surgeries.
Good Faith Exam. A medical exam by our licensed medical staff before any testing or care plan.
Review of your prior workup. Colonoscopy, endoscopy, imaging and blood work, so nothing is repeated without a reason.
GI and SIBO breath testing. Ordered when it adds useful information, with clear instructions for preparation.
Results visit. We explain what the results do and do not show and what that means for next steps.

What SIBO care can involve

Care is set after testing and depends on your results and history. Standard medical options for SIBO include prescription antibiotics chosen by your medical team. Plans often also look at why the overgrowth happened, such as slow gut movement, medications or another condition, along with diet changes during and after treatment. SIBO can come back, so follow-up matters. We work alongside your gastroenterologist or primary care doctor rather than replacing them, and no specific result is promised.

Care options at Venturis

SIBO is often not the only thing going on. When your exam and testing point to an overlapping condition, our team may discuss other options for that condition:

EBOO therapy in Oklahoma City is not a gut treatment, and we do not offer it for SIBO. It is sometimes discussed when a workup shows an overlapping condition such as long COVID or mold-related illness.
If labs show low B12 or other nutrient shortfalls, IV nutrients such as a Myers’ cocktail IV may be discussed. See the full IV therapy menu.

These are options that may be discussed after the Good Faith Exam, not a standard part of SIBO care.

SIBO FAQ

Is SIBO the same as IBS?

No. SIBO is one possible cause of IBS-type symptoms, and studies suggest it is found more often in people with IBS. Many people with IBS do not have SIBO.

Can I do a SIBO breath test at home?

Yes. Most breath tests are collected at home with a kit and mailed to the lab, after we go over the preparation with you.

What is the difference between hydrogen and methane SIBO?

They describe which gas rises on the test. Hydrogen is linked more with diarrhea and methane, now often called IMO, more with constipation.

Does SIBO come back?

It can, especially if the underlying cause, such as slow gut movement, is still present. That is why follow-up is part of the plan.

Do I need a referral?

In most cases, no. Bring any prior gut test results to your first visit.

Venturis Clinic is at 7917 N. May Ave., Suite B, Oklahoma City, OK 73120. We see patients from Oklahoma City and surrounding areas, including Edmond, Norman and Tulsa.

Talk it through first

Not sure whether SIBO testing makes sense for you? Talk with our team for 15 minutes, at no cost, and we will help you decide on a sensible next step.

Book your free 15-minute discovery call or call (405) 848-7246.

This page is educational and is not a diagnosis or medical advice.

SIBO Testing and Treatment in Oklahoma City