SIBO Treatments and Medications

What is SIBO?

Small intestinal bacterial overgrowth (SIBO) occurs when there are excess or invasive bacteria in the small intestine. Many symptoms are barely noticeable or mild but some patients may experience painful symptoms and dangerous malnutrition.

• Reduced small intestine motility: 90% of SIBO cases are caused by small intestine dysmotility. Irritable bowel syndrome, diabetes, inflammatory bowel disease, Crohn’s disease, celiac disease, hypothyroidism, narcotic use, and scleroderma can slow down small bowel movement.
• Pancreas problems Chronic pancreatitis is another major risk factor, reducing the digestive enzymes that break down bacteria.
• Anatomic problems: Anything that causes material in the small intestine to slow down, such as diverticulitis, short bowel syndrome, gastric bypass, and other surgeries slows down small intestinal motility and raises the risk of SIBO.
• Reduced stomach acid: Stomach acid kills bacteria as they pass through the stomach. People with low stomach acid or who take proton pump inhibitors (acid reducers) may be more vulnerable to SIBO.
• Compromised immune system: Age, AIDS/HIV, and medications can all reduce the immune system’s ability to produce antibodies that keep bacteria in the small bowel in check.

How is SIBO diagnosed?

Diagnosis will be made based on a physical exam, medical history, physical symptoms, breath testing, and bacterial cultures. A family healthcare provider may start the process, but a gastroenterologist will make the final diagnosis.

SIBO symptoms

Physical symptoms will vary based on the types of bacteria that are growing in the small intestine. These symptoms may include:

• Abdominal pain
• Bloating
• Flatulence
• Watery diarrhea
• Oily stools
• Weight loss
• Signs of nutritional deficiency, such as anemia

Carbohydrate breath test

A combined methane and hydrogen breath test can help but not definitively diagnose SIBO. When they consume carbohydrates, bacteria excrete gases such as hydrogen or methane, depending on the type of bacteria. The patient breathes into a device. The hydrogen and methane in the patient’s breath are measured. The patient is then fed a solution of sugars, either lactose or lactulose, and then breathes into the machine at regular intervals. If there are too many bacteria in the small intestine, the amount of one or more of these gases will increase substantially as the bacteria start digesting the sugars. Test results can identify both hydrogen-producing and methane-producing bacteria, a distinction that can help determine what antibiotics to use.

Jejunal aspirate cultures

A more certain test is to extract material from the small intestine using an endoscope threaded through the alimentary canal, called jejunal aspiration, and then culture it to discover the bacteria growing there. Culturing the bacteria has the benefit of identifying specific types of bacteria and can help determine what antibiotics to use.

Other tests

A gastroenterologist may order blood tests to identify vitamin levels or other metabolic indicators of malnutrition. SIBO treatment always involves treating the underlying cause, so further tests and imaging may be required to identify motility, pancreas, or immune system problems.

SIBO treatment options

Treatment of SIBO involves antibiotic medications to reduce the infection, nutritional support, and treatment of the underlying cause.

Medications

The cornerstone of SIBO treatment is a one- to two-week course of antibiotics which will reduce the bacterial overgrowth, reduce swelling in the small intestinal lining, and help restore absorption of nutrients. Rifaximin (Xifaxan) is the most commonly prescribed medication, but the gastroenterologist will prescribe antibiotics specific to the types of bacteria found in the diagnostic tests.

Nutritional support

Dietary supplements will be prescribed or advised during treatment to address specific deficiencies, particularly B12 or fat-soluble vitamins. There is no consensus about the right diet to follow during antibiotic treatment. Some healthcare providers will put patients on a low carbohydrate diet to starve the bacteria of needed food and curb overgrowth. Some health care professionals will recommend a diet low in fermentable carbohydrates following treatment to prevent a recurrence.

Underlying cause treatments

The treatment of the underlying cause may involve medications, surgery, or dietary changes.

Elemental diet

As a last resort, patients with SIBO who are not responding to antibiotics may be put on an elemental diet. The goal of the elemental diet is to starve the bacteria of sugars, fats, and proteins. Limiting food intake to three nutrition shakes a day, the elemental diet replaces sugars, fats, and proteins with glucose, fatty acids, and amino acids. A two-week elemental diet has been shown to be effective in decreasing overgrowth and improving symptoms, but it is costly and many patients can’t stick to it.

SIBO medications

SIBO medical treatment involves a one- to two-week course of antibiotics along with dietary supplements in people with signs of deficiencies.

Antibiotics

Antibiotics can help reduce the number of excess bacteria in the small bowel. Bacterial cultures will determine the most effective antibiotics, but off-label, high-dose rifaximin (Xifaxan) is most often used in infections of predominantly hydrogen-producing bacteria. If methane-producing bacteria are present, neomycin may be prescribed in addition to rifaximin. Although rifaximin is very expensive, it is active only in the gastrointestinal tract and, therefore, has fewer side effects than systemic (whole-body) antibiotics. Depending on the bacteria cultured from the small intestine, a gastroenterologist might prescribe metronidazole, amoxicillin-clavulanate, ciprofloxacin, norfloxacin, or tetracycline. For SIBO, antibiotics are being used off-label, and there is no standard FDA-approved dosage.

Supplements

If there are signs of nutritional deficiencies, dietary supplements may be advised or prescribed, most typically cobalamin (Vitamin B12), fat-soluble vitamins (vitamins A, D, E, and K), and protein.

What is the best medication for SIBO?

SIBO is treated by antibiotics, but a wide variety of bacteria are responsible for the condition. For this reason, the “best” antibiotic will be the one most suitable for the bacteria causing the condition. Physicians will tailor the prescription to the predominant bacteria and the patient’s history of sensitivity to antibiotics.

What is the best home remedy for SIBO?

The best treatment for SIBO is a course of antibiotics, but these medications do not always resolve the condition. Alternative therapies, such as diet and herbal antibiotics, may help manage symptoms and prevent a recurrence.

Eat on a regular schedule

90% of SIBO cases are due to small intestine motility problems, that is, the small intestine is not moving material out fast enough. The small intestine runs in two gears. When people eat, the small intestine slows down to give food enough time to digest. About an hour and a half after eating, the small intestine then speeds up to clear everything out, called “motility motor complex.” When people eat throughout the day, the small intestine spends most of its time in slow gear, providing a good environment for bacteria to grow. The best way to prevent or minimize the symptoms of SIBO is to eat three meals a day, minimize snacking, and avoid eating before bedtime.

Diet

A diet low in fermentable carbohydrates cannot cure SIBO, but it can help manage the symptoms and may prevent a recurrence. Healthcare professionals usually recommend the low-FODMAP diet (for “low fermentable oligosaccharides, disaccharides, monosaccharides, and polyols diet) after antibiotic treatment. These carbohydrates include fructose, fructans, lactose, galactans, and sugar alcohols. They are difficult to break down and are not immediately absorbed by the small intestine. They provide a rich food supply for bacteria. Other common SIBO diets include the Cedars-Sinai Low Fermentation Diet, the Bi-Phasic Diet, the GAPS diet, and the Specific Carbohydrate Diet.

Herbal antibiotics

A healthcare professional will not prescribe or recommend herbal antibiotics, but they may be effective as an alternative medical treatment. At least four products have been shown in one study to reduce small intestine bacterial overgrowth almost as effectively as antibiotics. This includes a combination of Candibactin-AR/Candibactin-BR and a combination of Dysbiocide/FC-Cidal. The results of this study have not been verified, so the effectiveness of herbal antibiotics has not been definitively proven.

Probiotics and prebiotics

Probiotics may be recommended for SIBO. However, SIBO is not a failure of “good” bacteria suppressing “bad” bacteria as might happen during a colon infection. Instead, SIBO is an overgrowth of bacteria not usually found in the small bowel, so many doctors question the wisdom of adding even more bacteria to the mix. While certain probiotic bacteria, such as Lactobacillus, may have some effect, research hasn’t concluded that probiotics and prebiotics affect SIBO one way or the other. Some physicians, however, may recommend probiotics to prevent SIBO. Prebiotics are high in fermentable carbohydrates so their use is not advised.

What is the best treatment for SIBO?

SIBO is treated with antibiotics and nutritional support. SIBO is not so much an “infection” as it is an overgrowth of bacteria already living in the small intestine. It is usually the result of some other problem, such as gastric bypass surgery or conditions that cause a loss of intestinal motility. So, in addition to antibiotics and nutritional support, the underlying cause will be treated with medicines, diet, or surgery.

Can probiotics make SIBO worse?

Probiotics are taken to maintain a healthy population of “good” bacteria in the colon. While many specialists don’t recommend probiotics, there is conflicting evidence on the effectiveness of probiotics for SIBO. Some studies suggest that probiotics may be helpful for improving symptoms after a course of antibiotics. However, other studies show that probiotics can make symptoms worse, and the current scientific consensus is that probiotics and prebiotics accomplish little in treating or preventing SIBO.

Can SIBO be cured?

SIBO can be cured in most people by treating the underlying cause and eradicating the bacterial overgrowth with one or two weeks of antibiotic therapy. The effectiveness of antibiotics, however, may be limited. In many cases, patients successfully treated with antibiotics will experience SIBO again within nine months.

What are the side effects of rifaximin?

Oral rifaximin does not get into the bloodstream, so its side effects are limited to gastrointestinal problems such as nausea, vomiting, stomach upset, and diarrhea.

What foods to eat if you have SIBO?

A diet low in hard-to-digest carbohydrates (fermentable oligosaccharides, disaccharides, monosaccharides, and polyols, or FODMAP) can help reduce the symptoms of SIBO and, after treatment, may prevent a recurrence. Low-FODMAP foods include leafy vegetables, fruits low in fructose, unprocessed meats, fish, seafood, nuts, wheat-free bread, sugar-free sweeteners, and low-lactose dairy products.

What foods should be avoided with SIBO?

A diet high in hard-to-digest carbohydrates provides a rich source of food for the bacteria overgrowing the small intestine. The main culprits are fructose (found in wheat and processed foods), fructans (found in wheat), lactose (found in dairy products), galactans (found in legumes), and sugar alcohols (such as mannitol and sorbitol). Foods to avoid include high-fructose fruits and foods (such as soda), legumes, starchy vegetables, wheat products, high-lactose dairy products, processed meats, processed foods, and prebiotics.

What happens if SIBO is left untreated?

Bacterial overgrowth in the small bowel uses up nutrients needed by the body, such as vitamin B12, proteins, and fats. Also, lowering the fat content of the small intestine reduces the body’s ability to absorb fat-soluble vitamins such as vitamins A, D, E, and K. Severe, untreated SIBO can result in life-threatening malnutrition. It can also damage the small intestine tissues and lead to intestinal failure.

How can I treat SIBO naturally?

Science is uncertain if SIBO can resolve naturally and, if so, how commonly this occurs. Antibiotic therapy is not always successful and recurrence is high, so natural treatment may be a good alternative. The most effective natural treatments for reducing SIBO symptoms are:

• Eat on a regular schedule, minimize snacking, and avoid eating at bedtime
• Eat foods low in fermentable carbohydrates
• Take herbal antibiotics that have been shown to reduce both symptoms and bacteria populations in people with SIBO

How long does it take for Xifaxan to work for SIBO?

Xifaxan is prescribed off-label for SIBO, so there is no set therapy for its use. Three different high-dose treatment regimens are used and usually last from seven to 14 days. Patients should experience symptom relief after completing the treatment course.

Does rifaximin kill good bacteria?

Rifaximin kills many of the bacteria associated with SIBO but does not seem to affect many of the bacteria native to the colon’s microbiome.

Are bananas good for SIBO?

Bananas contain both fructose and resistant starches, both of which feed the bacteria that cause SIBO. They are often recommended as a good source of prebiotics, which will only worsen SIBO symptoms. For all these reasons, both the low-FODMAP diet and the Cedars-Sinai Low Fermentation Diet recommend avoiding bananas.

Related resources for SIBO

• 4 Facts about SIBO the Internet Keeps Getting Wrong
• Cedars-Sinai Low Fermentation Diet
• FODMAP Food List
• How Gut Health Impacts Your Well-Being
• How to Avoid Fermentable Carbs
• Small Intestinal Bacterial Overgrowth: A Comprehensive Review
• Small Intestinal Bacterial Overgrowth: Clinical Features and Therapeutic Management