Small intestinal bacterial overgrowth (SIBO) is an excess of bacteria in the small intestine, where relatively few normally live. It causes bloating, gas, abdominal pain, and changes in bowel habits, and it is closely linked to IBS. At Orlando Gastroenterology, our board-certified gastroenterologists diagnose SIBO with breath testing and treat it at four locations across Orlando, Clermont, Kissimmee, and East Orlando.
Small intestinal bacterial overgrowth (SIBO) occurs when bacteria that belong mainly in the colon build up in the small intestine, or when the normal small-intestine bacteria grow out of balance. These bacteria ferment food before it is fully digested, producing gas and interfering with nutrient absorption. The result is often uncomfortable bloating and digestive symptoms that can be mistaken for other conditions.
SIBO symptoms overlap with several other digestive disorders, which is why testing matters. Common symptoms include:
In longer-standing cases, unintended weight loss or nutrient deficiencies (such as vitamin B12)
SIBO develops when something disrupts the small intestine’s ability to keep bacteria moving and in balance. Contributing factors include slowed gut motility (as in some cases of IBS or gastroparesis), prior abdominal or bowel surgery, structural issues such as strictures or diverticula, certain medications that reduce stomach acid or slow the gut, and conditions like diabetes or scleroderma. Because these causes vary, treatment works best when the underlying trigger is identified.
SIBO is most commonly diagnosed with a breath test. After drinking a sugar solution (glucose or lactulose), you provide breath samples over a few hours; elevated hydrogen or methane gas indicates bacterial overgrowth. Our gastroenterologists interpret the results alongside your symptoms and history, and may recommend additional testing to look for an underlying cause. Because SIBO and IBS frequently coexist, we evaluate for both.
Treatment usually combines a course of antibiotics that targets bacteria in the small intestine with steps to address the underlying cause and prevent recurrence. Dietary adjustments — sometimes a temporary low-fermentation or low-FODMAP approach guided by your provider — can reduce symptoms, and treating any motility problem or structural issue lowers the chance the overgrowth returns. Because SIBO can recur, our team builds a follow-up plan rather than treating it as a one-time fix.
Recurrence is the most frustrating part of SIBO, and it is common — a substantial share of patients see symptoms return within a year of otherwise successful treatment.
The reason is that antibiotics clear the overgrowth but do not necessarily correct whatever allowed it to happen. SIBO is usually a downstream problem. If the underlying driver is still in place — slow motility in the small intestine, gastroparesis, scarring or adhesions from previous abdominal surgery, low stomach acid, or a structural issue such as a blind loop — bacteria will simply recolonise.
That is why we look for the cause rather than repeating the same course of antibiotics indefinitely. Depending on what we find, follow-up may involve a prokinetic to keep the small intestine moving between meals, spacing meals so the gut’s natural clearing wave can do its job, treating the underlying condition directly, or repeating the breath test to confirm the overgrowth actually cleared before we change anything else.
If your SIBO has returned more than once, that is a reason to be re-evaluated — not a reason to keep re-treating the same way.
A significant share of people diagnosed with irritable bowel syndrome (IBS) — particularly those with prominent bloating — also have SIBO, and treating the overgrowth can ease IBS symptoms. If you have been told you have IBS but continue to struggle with bloating and gas, ask our team whether breath testing for SIBO is appropriate.
Several conditions produce bloating, gas, and unpredictable bowel habits that look a great deal like SIBO, which is why we test rather than treat on symptoms alone.
The most frequent overlaps are irritable bowel syndrome, celiac disease, lactose intolerance, and straightforward gas and bloating from diet or swallowed air. Gluten intolerance can present almost identically. Pancreatic insufficiency and gastroparesis are less common but matter a great deal, because both are managed very differently from SIBO.
Getting this distinction right is not academic. A course of antibiotics aimed at SIBO will do nothing for celiac disease, and months on a restrictive diet will not resolve a motility problem. A breath test alongside the right blood work usually separates them quickly.
The symptoms overlap heavily, so the two are hard to tell apart by feel alone. A breath test can identify bacterial overgrowth, and many people have both conditions at once. A gastroenterologist can determine which is driving your symptoms.
SIBO can usually be treated successfully, but it can also come back if the underlying cause is not addressed. That is why treatment focuses on both clearing the overgrowth and correcting what allowed it to develop.
There is no single SIBO diet, but many patients benefit from a temporary low-fermentation or low-FODMAP eating plan while under a provider’s guidance. Long-term, the goal is to reintroduce foods and restore a normal, varied diet.
The SIBO breath test takes about two to three hours and is done after an overnight fast. You drink a sugar solution and provide breath samples at set intervals.
External Citation: Mayo Clinic — SIBO
Medically reviewed by Dr. Soto-Ramos
Related: IBS · Gas & Bloating · Chronic Diarrhea · Gastroparesis
Our locations: Orlando (MetroWest) · Clermont · Kissimmee · East Orlando
