If you’re like most people who suffer from nagging digestive problems, such as bloating, stomach pain and diarrhea or constipation, you’ve probably been told that you have irritable bowel syndrome (IBS). But that’s not the whole story.

Problem: The symptoms of another common intestinal illness, known as small intestinal bacterial overgrowth (SIBO), are similar to those of IBS. As a result, SIBO often gets missed. It’s important to recognize SIBO, as this can dictate the type of treatment for this condition.

Good news: Researchers from Cedars-Sinai in Los Angeles recently identified a way to improve the diagnosis and treatment of patients with this IBS-related condition.

Background: SIBO is caused by having too much of certain strains of bacteria in the small intestine. In up to 78% of patients who are diagnosed with IBS, the actual culprit is SIBO.

Even though it’s normal (even desirable) for bacteria to live in the digestive tract, the problem with SIBO is that there is too much bacteria—or the wrong type. These bacteria produce excessive amounts of methane gas, one of several types of gas that can lead to flatulence. Methane (along with other gases such as hydrogen) is produced when certain foods (mainly carbohydrates) combine with gas-forming bacteria.

Current test: Even though IBS tends to be the catchall default diagnosis for people with gastrointestinal (GI) problems, a breath test can be used to determine whether SIBO is present. The test is simple: After a one-day diet that eliminates foods that feed bacteria, you drink a sugar solution and breathe into a device that captures a sample of your breath. A positive breath test for hydrogen or methane gas explains the most common symptoms of SIBO—gas and bloating…flatulence…belching…abdominal pain or cramping…and constipation.

The problem is, methane gas is linked to constipation, but hydrogen has not been linked to the diarrhea that is experienced by many SIBO patients, so doctors knew there was something missing from the routine test for this condition.

Latest development: A large clinical trial has linked the presence of another gas, hydrogen sulfide, to the symptom of diarrhea. That result led to the development of the new breath test device, which is sensitive to four gut gases (carbon dioxide, methane, hydrogen and hydrogen sulfide) that are new hallmarks of SIBO. The new test is scheduled to become available by the end of 2018.

Why this matters: Without an accurate diagnosis, patients with SIBO are unlikely to be prescribed the correct antibiotics (typically a 10- to 14-day course)—the treatment of choice for this condition. The distinction is crucial because IBS is usually treated with self-care approaches, such as diet and stress management…and/or medication, such as dicyclomine, an antispasmodic for bowel spasms—but not antibiotics. Exception: In IBS patients with high levels of hydrogen sulfide, antibiotics may also provide relief when used in conjunction with IBS medication. Rifaximin (Xifaxan), a broad-spectrum antibiotic that is often used to treat SIBO, has been shown to reduce bloating, abdominal pain and loose stools in patients with diarrhea-predominant IBS.

Bottom line: If you struggle with digestive problems, talk to your doctor about both IBS and SIBO. Proper testing will help ensure that you get the best possible treatment.

For more on common causes of stomach distress, read here.

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