SIBO that keeps coming back is telling you something
You took the antibiotics. You did the diet. Maybe you even tried the herbs. For a few weeks you felt like yourself again. Then the pressure, the gas and the afternoon distention came back, and you started the cycle over.
If that sounds familiar, you are not failing treatment. Recurrence is information. When SIBO returns again and again, it usually means something is still allowing bacteria to settle and multiply in the small intestine. Clearing the overgrowth matters. Finding what lets it come back matters more.
At our Manhattan practice, Dr. Raphael Kellman approaches SIBO the way he approaches every chronic condition: by asking what changed in the body's environment, not just which organisms are present. We call this looking for the root beneath the root.
Why SIBO keeps coming back
Antibiotics are an evidence-supported treatment for properly diagnosed SIBO, and rifaximin is the best studied. But clearing the overgrowth is often not the end of the story. In one study of patients whose SIBO had been successfully treated, the breath test turned positive again in:
Those numbers are not an argument against treatment. They are an argument against stopping the investigation at the bacteria.
Think of water that keeps collecting on the floor. Mopping is necessary, but the puddle is not the whole problem. Something is letting the water back in. The American College of Gastroenterology says the same thing in its SIBO guideline: treating the underlying cause is the primary way to reduce recurrence. That principle sits at the center of how Dr. Kellman builds a SIBO plan.
The root beneath the root
SIBO describes what is happening in the small intestine. It does not always explain why it started. The small intestine normally holds relatively few bacteria because food keeps moving, stomach acid filters microbes, and bile and digestive enzymes keep the environment in check. When one of those defenses weakens, overgrowth gets its opening.
The most common contributors Dr. Kellman looks for:
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1Slow motility. Between meals, a cleansing wave called the migrating motor complex sweeps the small intestine clean. When it weakens, food and bacteria linger. Research in patients with abnormal breath tests found fewer of these cleansing waves.
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2Low thyroid function. Thyroid hormone sets the tempo of the gut. A slow thyroid can mean a slow intestine.
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3Low stomach acid. Acid is the upper gut’s microbial filter. H. pylori, autoimmune gastritis and long-term acid-suppressing medication can all reduce it.
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4Weak digestion. Pancreatic enzyme or bile problems leave undigested food behind for bacteria to ferment.
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5Constipation and pelvic-floor dysfunction. If the exit is blocked, pressure and fermentation build upstream, even with a daily bowel movement.
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6Medications. Opioids, some antidepressants, iron, acid suppressants and GLP-1 drugs can slow the gut.
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7Structural factors. Adhesions, prior surgery, strictures or diverticula can create places where contents stall.
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8Nutrient gaps. Certain deficiencies affect the nerves and muscles that move the gut.
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9The brain–gut axis. Stress does not make symptoms imaginary, but it does change motility, sensation and immune signaling.
Often more than one is involved. A durable plan addresses the ones that apply to you.
SIBO, methane overgrowth and IBS are not the same
These labels are often used interchangeably. They shouldn't be, because each points to a different plan.
Small intestinal bacterial overgrowth
Excess bacteria in the small bowel that causes symptoms such as bloating, gas, pain, diarrhea or nutrient problems. It is usually linked to hydrogen on a breath test.
Intestinal methanogen overgrowth
Often called “methane SIBO,” but the organisms involved are archaea, not bacteria, and they can live in the colon as well. Methane is closely tied to constipation and slow transit, so repeating the same antibiotic used for hydrogen SIBO often misses the point.
Irritable bowel syndrome
A disorder of gut–brain interaction defined by abdominal pain and changed bowel habits. IBS and SIBO can overlap, but you can have one without the other, and symptoms can persist after an overgrowth is treated.
Getting the pattern right is the first step. Treating every distended abdomen as SIBO guarantees that many people will stay sick.
The thyroid–motility connection
Thyroid hormone helps set the speed of the whole body, including the gut. When thyroid signaling is low, the esophagus, stomach, small intestine and colon can all slow down. Constipation is the best-known sign, but bloating, reflux, early fullness and nausea can appear too.
These are associations, and low thyroid is not the cause of every case. But in the right patient, it may be the hidden slowdown that lets SIBO return. If your SIBO keeps coming back and you also feel cold, tired, foggy or constipated, your thyroid deserves a careful look, beyond a single TSH result.
Learn how Dr. Kellman evaluates the thyroid →The research link to SIBO is striking
In a 2007 study, 54% of patients with a history of autoimmune hypothyroidism had a positive SIBO breath test, compared with 5% of controls.
One study found that stopping thyroid medication in older adults nearly doubled the time it took food to reach the colon (75 to 135 minutes), and restarting it brought the time back down.
Testing that answers a question
A longer lab list is not automatically a deeper evaluation. Every test should answer a specific question about your care.
First, we define your pattern. When does the bloating start, and is it upper or lower abdominal? Does passing stool or gas relieve it? Are stools hard, loose, greasy or incomplete? Did symptoms begin after food poisoning, antibiotics, surgery, pregnancy or a new medication?
Then we choose tests that fit. Depending on your history, that may include:
- Hydrogen–methane breath testing, with the right preparation and substrate (glucose or lactulose)
- Thyroid evaluation beyond a reflex TSH: TSH and free T4 read together, antibodies when autoimmunity is suspected, and your results over time
- Blood count, iron, B12 and other nutrients when indicated
- Celiac screening and inflammation markers when the pattern calls for it
- H. pylori testing for upper-gut symptoms
- Pancreatic or bile evaluation when digestion looks weak
- Motility or pelvic-floor testing for stubborn constipation
Bring your previous results. Past breath tests, lab reports and treatment history help us see what has already been tried and why it didn't hold.
The Unbloating approach: six phases
Dr. Kellman's plans are layered. The order changes with each patient, but the structure stays the same:
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Phase 1Restore movement and the exit.Treat constipation early, correct pelvic-floor problems, review medications that slow the gut, and treat established thyroid dysfunction. Spacing meals can also give the gut’s cleansing wave time to work.
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Phase 2Restore digestion.Address H. pylori, low acid, or pancreatic and bile problems when they are present, based on testing rather than guesswork.
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Phase 3Selectively prune a documented overgrowth.Use targeted antibiotics or botanicals when testing supports it, matched to the pattern (hydrogen vs. methane).
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Phase 4Rebuild the microbiome.Expand the diet after any short restriction, reintroduce foods methodically, and choose probiotics by strain and pattern, not marketing.
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Phase 5Retrain sensation and mechanics.For a sensitive gut or visible distention, add approaches such as diaphragmatic breathing, gut-directed therapy or pelvic-floor rehabilitation.
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Phase 6Prevent recurrence.Track bowel habits, early warning signs and thyroid status, and reassess rather than repeat the same treatment automatically.
The goal is not to sterilize the intestine. It is to restore an environment where your microbes, digestion and gut movement can work together again. This is the heart of Microbiome Medicine.
Frequently asked questions
Can SIBO be cured?
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An overgrowth can often be cleared, but whether it stays away depends on what allowed it in the first place. That is why Dr. Kellman focuses on motility, thyroid function, digestion and the other underlying drivers alongside treating the bacteria.
What causes SIBO?
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Usually a combination of factors that let bacteria settle in the small intestine: slow gut movement, low stomach acid, weak digestion, constipation, certain medications, prior surgery or low thyroid function.
How do you test for SIBO?
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The most common test is a hydrogen–methane breath test after drinking glucose or lactulose. It is useful but imperfect, so results should be read alongside your symptoms and history.
Can SIBO go away on its own?
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Symptoms can rise and fall, but if the underlying cause is still present, overgrowth tends to persist or return. A proper evaluation is the best way to know what is driving yours.
Can SIBO be treated naturally?
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Botanical antimicrobials are an option for some patients, with more limited evidence than antibiotics. In either case, the more important work is correcting the conditions that let SIBO return.
What does a consultation cost?
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The initial consultation with Dr. Kellman is $575. The practice is private-pay. Bring previous breath tests and lab results.
Let's find what keeps your SIBO coming back
If you've been treated before and the symptoms keep returning, bring your history and your results. Dr. Kellman will look at the whole pattern (motility, thyroid, digestion and the microbiome) and build a plan designed to last.
Want the full explanation first? The Book of Unbloating is Dr. Kellman's 15-chapter guide to bloating, SIBO and the root beneath the root, including his complete testing map and treatment architecture.
Raphael Kellman, MD
Dr. Kellman trained in internal medicine at Albert Einstein College of Medicine of Yeshiva University. Over more than 25 years of practice, he has treated more than 60,000 patients — many arriving after years of unexplained symptoms and dismissed concerns.
He is credited with coining the term "Microbiome Medicine," recognizing the gut microbiome's role as a central regulator connecting immune, thyroid, and metabolic function. This framework underlies his approach to autoimmune disease, thyroid disorders, mood and cognitive symptoms, and chronic digestive issues. He has written 10+ books exploring the microbiome, gut health, and the gut-brain axis.
More about Dr. Kellman →This page is educational and is not a substitute for individualized medical diagnosis or treatment. Persistent or severe bloating can accompany conditions that need prompt evaluation. Seek medical care for gastrointestinal bleeding, black stools, persistent vomiting, fever, jaundice, severe or rapidly increasing abdominal pain, unintentional weight loss, or an inability to pass stool or gas. Supplements and herbs can interact with medications.
References
- Pimentel M, et al. ACG Clinical Guideline: Small Intestinal Bacterial Overgrowth. Am J Gastroenterol. 2020;115:165–178.
- Lauritano EC, et al. Small intestinal bacterial overgrowth recurrence after antibiotic therapy. Am J Gastroenterol. 2008.
- Lauritano EC, et al. Association between hypothyroidism and small intestinal bacterial overgrowth. J Clin Endocrinol Metab. 2007.
- Rezaie A, et al. Hydrogen and Methane-Based Breath Testing in Gastrointestinal Disorders: The North American Consensus. Am J Gastroenterol. 2017.
- Lacy BE, et al. ACG Clinical Guideline: Management of Irritable Bowel Syndrome. Am J Gastroenterol. 2021.