What causes burps to taste and smell like feces in a patient with potential gastrointestinal issues such as Gastroesophageal Reflux Disease (GERD), Irritable Bowel Syndrome (IBS), Small Intestine Bacterial Overgrowth (SIBO), or Inflammatory Bowel Disease (IBD)?

Feculent Burps: Causes and Management

Burps that taste and smell like feces most commonly indicate small intestinal bacterial overgrowth (SIBO), where pathogenic bacteria produce hydrogen sulfide and other foul-smelling gases through fermentation of undigested food in the small intestine. 1, 2

Primary Mechanisms

The feculent odor and taste result from bacterial production of hydrogen sulfide and other sulfur-containing gases. This occurs through several pathways:

• SIBO causes overgrowth of sulfate-reducing bacteria (including Enterococcus, E. coli, and Klebsiella) that produce excess hydrogen sulfide through fermentation 1, 2
• Gastroparesis allows prolonged bacterial fermentation of sulfur-containing foods in the stomach before emptying 1
• GERD-associated gastric belching can transport these malodorous gases upward through spontaneous transient lower esophageal sphincter relaxation 3, 1

Diagnostic Workup

Start with targeted testing based on associated symptoms:

• Hydrogen breath testing (glucose or lactulose-based) measuring hydrogen, methane, and CO₂ to diagnose SIBO or carbohydrate malabsorption 4, 1
• H. pylori testing via stool or breath test, as this infection alters gastric function and contributes to dyspeptic symptoms 4, 1
• High-resolution esophageal manometry with impedance-pH monitoring if excessive belching is the primary complaint, to differentiate gastric from supragastric belching 3, 1

Order upper endoscopy only if alarm features are present: age ≥55 years with new-onset symptoms, weight loss >10%, signs of malnutrition, GI bleeding, iron-deficiency anemia, or severe dysphagia 5, 4

Treatment Algorithm

First-Line: Dietary Modification (2-Week Trial)

• Reduce high-sulfur foods including eggs, meat, cruciferous vegetables, garlic, and onions 1
• Eliminate sugar alcohols and sorbitol which increase bacterial fermentation 1
• Consider carbohydrate restriction targeting lactose, fructose, and FODMAPs if bloating and diarrhea are prominent 4

Second-Line: Pharmacologic Therapy

If dietary modification fails after 2 weeks:

• For confirmed SIBO: Rifaximin is the most studied antibiotic, though metronidazole is an alternative (note: metronidazole causes metallic taste, GI upset, and requires alcohol avoidance) 4, 6
• For GERD-related gastric belching: Omeprazole 20 mg daily combined with diaphragmatic breathing techniques 3, 4, 1
• For positive H. pylori: Appropriate antibiotic eradication regimen 4, 1

Adjunctive Behavioral Therapy

• Diaphragmatic breathing reduces excessive belching by increasing vagal tone and inducing relaxation 3, 4, 1
• Brain-gut behavioral therapy (cognitive behavioral therapy, gut-directed hypnotherapy) if symptoms significantly impact quality of life 4

Common Pitfalls

Do not order gastric emptying studies routinely—reserve these only if nausea and vomiting suggest gastroparesis 5

Do not use probiotics—they are not effective for treating bloating and distention 5

Avoid opioid analgesics for any associated abdominal pain, as they worsen gastric emptying and gas symptoms 4

When Urgent Evaluation Is Required

Seek immediate workup if feculent burps occur with:

• Age ≥55 years with new-onset symptoms 3, 4
• Weight loss >10% or malnutrition 3, 4
• GI bleeding or iron-deficiency anemia 3, 4
• Chronic watery diarrhea suggesting high-risk SIBO 4
• Severe dysphagia suggesting structural obstruction 3