McCall McPhersonFounder, Modern Thyroid Clinic.

SIBO symptoms to look out for #sibo #sibolife #smallintestinalbacteriaovergrowth #sibotreatment

28 Jun 2026 · 2 min

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1:55

In this video, McCall McPherson explains the strong association between small intestinal bacterial overgrowth (SIBO) and hypothyroidism, noting that about 54% of people with hypothyroidism have SIBO compared to only 5% of the general population. She attributes the link to reduced stomach acid in hypothyroid patients, which creates an environment for bacterial overgrowth in the upper gastrointestinal tract where bacteria normally do not reside. The resulting overgrowth leads to fermentation of food, producing methane and hydrogen gases that cause hallmark symptoms such as bloating, belching, and burping after meals or even after drinking water, as well as visible abdominal distention, inflammation, and irregular bowel movements (diarrhea and/or constipation). McPherson describes treatment as challenging, often requiring multiple rounds of antibiotics and sometimes antifungals, and emphasizes the need for a supportive partner during the long‑term management process. Crucially, she stresses that without addressing the underlying thyroid dysfunction—and thereby restoring adequate stomach acid—any bacterial eradication is likely to be temporary, leading to recurrence of SIBO.

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SIBO, especially in the thyroid world, is an issue. So 54% of people with hypothyroidism have SIBO in some studies versus 5% of the general population without thyroid issues. And it's because we lose our stomach acid. That loss of stomach acid creates an environment for bacteria to flourish in our upper GI tract where we're not actually supposed to have bacteria. That is in our lower GI tract. So hypothyroidism and SIBO go hand in hand. Symptoms are bloating, after you eat, even sometimes in severe cases after you drink water. And what's happening is we're eating, the food is going into our stomach where we should have acid secreted to break it down, and then it moves along. In SIBO, we don't have enough stomach acid and we have a lot of bacteria. So we eat, food goes in, and it almost ferments, and that bacteria releases a lot of methane and hydrogen gas, which pushes air up and makes us burp. Hallmark classic SIBO. Burping, belching after eating. I look pregnant. In fact, I'll drop a photo of me here when I had my SIBO. It was horrible. It was absolutely horrible compared to a photo of me when I was 8 months pregnant in the same dress. It is wild, y'all. So it's belching, burping, inflammation, like inflammation, you know, regardless of what you eat. Diarrhea and/or constipation are also super common symptoms. SIBO is pretty tricky to treat. Tricky to treat like that. Um, it often requires a few rounds of treatment with antibiotics, sometimes even antifungals, but you need to have a really good partner on your side with it because it's a long-term journey and not necessarily a quick fix. Most importantly, fix your thyroid because even if you get rid of all the bacteria, but you don't fix your thyroid, you don't produce enough stomach acid. It's just gonna come back.