Can SIBO cause acid reflux?

Yes, SIBO is a frequent hidden driver of chronic acid reflux and gastroesophageal reflux disease (GERD). When misplaced bacteria ferment dietary carbohydrates in the small intestine, they produce large volumes of hydrogen and methane gas. Because the small intestine is narrow, this gas buildup creates intense intra-abdominal pressure that pushes upward directly against the stomach. This physical pressure forces the Lower Esophageal Sphincter (LES)—the muscular valve separating the esophagus and stomach—to pop open. When the LES opens under pressure, stomach acid and digestive contents reflux upward into the esophagus, causing heartburn. To explore how low acidity worsens this loop, read our guide on [low stomach acid SIBO](/low-stomach-acid-sibo).

Disclaimer: This content is reviewed and fact-checked by Daryl Stubbs, Certified Holistic Nutritional Consultant (C.H.N.C), for educational purposes. It does not constitute medical advice or a doctor-patient relationship.