SIBO is small intestinal bacterial overgrowth — too many bacteria, or the wrong kinds, in the small intestine. It can interfere with digestion and cause bloating, gas, and changes in bowel habits.

How is SIBO diagnosed?

Usually with a breath test that measures gases produced by bacteria after drinking a sugar solution, sometimes with other tests. Symptoms alone can't confirm it, so a doctor's assessment is needed.

Is SIBO the same as IBS?

No, though they share symptoms and can overlap. SIBO is a bacterial overgrowth in the small intestine; a doctor can assess whether it's contributing to your symptoms.

Yes, SIBO can recur, so ongoing management is sometimes needed. Treatment is guided by a doctor and often addresses the underlying cause.

SIBO: Signs, Causes & What Helps

SIBO stands for small intestinal bacterial overgrowth — when too many bacteria, or the wrong kinds, build up in the small intestine. Bacteria belong mostly in the large intestine, so an overgrowth higher up can interfere with digestion and cause bloating, gas, and changes in bowel habits.

Quick answer: SIBO is an overgrowth of bacteria in the small intestine that can cause bloating, gas, diarrhea, and discomfort. Its symptoms overlap with IBS, so it's diagnosed by a doctor — often with a breath test — rather than guessed.

Common symptoms

Bloating, often worse after meals
Excess gas
Diarrhea, or sometimes constipation
Abdominal discomfort
In some cases, signs of poor nutrient absorption

Because these overlap heavily with IBS and other conditions, symptoms alone can't confirm SIBO.

What can contribute to SIBO

Slowed gut movement — when the small intestine doesn't clear bacteria as it should
Structural factors — changes in the gut anatomy can create areas where bacteria collect
Certain underlying conditions — some health conditions raise the risk

A doctor can explore whether any of these apply to you.

How SIBO is diagnosed

SIBO is typically assessed with a breath test, which measures gases produced by bacteria after you drink a sugar solution, sometimes alongside other investigations. Self-diagnosis is unreliable because so many conditions cause similar symptoms — a proper assessment matters.

What helps

Treatment is guided by a doctor and may involve addressing the underlying cause, dietary adjustments, and specific medical treatments. Because SIBO can recur, ongoing management is sometimes needed. Avoid self-treating based on an assumption — get it assessed first.

When to see a doctor

See a doctor for persistent bloating, gas, and changes in bowel habits, especially if they're affecting your daily life or come with weight loss or signs of poor absorption.

Track it with PoopID

A symptom record helps your doctor see the pattern and judge whether further testing is worthwhile. PoopID logs your Bristol type, frequency, and bloating from a photo. See the digestive conditions overview for related guides.

Sources:
NIDDK — Digestive Diseases. niddk.nih.gov
NHS — Bloating and gut symptoms. nhs.uk

This article is for general information only and is not medical advice. Consult a qualified healthcare professional about any symptom that concerns you.