Medically reviewed by Sumiran Racherla, MD, Internal Medicine. Last reviewed: October 23, 2026.
What kind of doctor provides SIBO Breath Test?
A gastroenterologist usually orders this test. A gastroenterologist is a doctor who treats digestive system problems. Your provider tells you which medicines to avoid and what to eat before the test. A direct primary care or concierge doctor can be a first stop for an evaluation and can refer you to a specialist when needed.
What it is
SIBO stands for small intestinal bacterial overgrowth. It is a condition in which very large numbers of bacteria grow in the small intestine. A hydrogen breath test is the most common way to measure the bacteria in your small intestine indirectly. Tests for this condition may include hydrogen and methane breath tests.
Why a doctor might recommend it
The most common symptoms of SIBO are the following.
- Belly fullness.
- Belly pain and cramps.
- Bloating.
- Diarrhea, most often watery.
- Gassiness.
Bacteria in the small intestine break food into gas and nutrients. Extra bacteria may lead to extra gas. SIBO is diagnosed when a person has digestive symptoms and signs of extra bacteria in the small intestine.
How to prepare
Your provider tells you how to get ready.
- Your provider will tell you to avoid some medicines, such as antibiotics and laxatives, for a few weeks.
- Your provider will also give you a diet to follow the day before.
What happens during it
Normally, a small amount of hydrogen is found in your breath. During the test, you will swallow a sugar. Bacteria in your small intestine break the sugar down. The gas they make leaves your body through your breath. Over a few hours, you breathe into a container that measures the hydrogen in your breath. During this time, a health care professional will ask you about your symptoms.
Recovery
Your breath is checked for hydrogen during a 3-hour period. A hydrogen level above the cut-off suggests excess bacteria. If your hydrogen levels go up and your symptoms get worse during the test, your doctor may diagnose a condition such as SIBO.
Call 911 or go to the emergency room if you have trouble breathing, chest pain or discomfort lasting two minutes or more, fainting, coughing up or vomiting blood, or bleeding that will not stop.
Risks and side effects
A breath test measures the amount of bacteria only indirectly. A SIBO diagnosis needs symptoms and signs of extra bacteria.
Who performs it
A gastroenterologist usually orders the test.
Common questions
What happens if the test shows SIBO?
SIBO can be treated with a short course of antibiotics. SIBO can come back after treatment and may need repeat treatment.
What conditions can lead to SIBO?
Diseases that slow the small bowel can lead to SIBO. Diabetes and scleroderma are examples. Crohn disease is one condition that can create pouches or blockages in the small intestine.
How long does the breath test take?
Your breath is checked for hydrogen during a 3-hour period. You breathe into a container over a few hours.
Do I need to change my diet or medicines before the test?
You will get diet instructions for the day before your test. Your provider will tell you to avoid some medicines, such as antibiotics and laxatives, for a few weeks.
How does a direct primary care or concierge doctor fit in?
A direct primary care doctor charges a flat monthly fee instead of billing insurance, while a concierge doctor usually charges more and often works alongside insurance.
Sources
- American College of Gastroenterology - Small Intestinal Bacterial Overgrowth (SIBO)
- NIDDK - Diagnosis of Diarrhea
- MedlinePlus - Small bowel bacterial overgrowth
Medical Disclaimer
This content is for general educational and informational purposes only and is not medical advice. It is not a substitute for professional medical advice, diagnosis, or treatment, and reading it does not create a doctor-patient relationship. Always seek the advice of your physician or another qualified health provider with any questions about a medical condition, and never disregard or delay seeking professional advice because of something you read here. If you think you may have a medical emergency, call 911 (or your local emergency number) immediately.
