Section Menu

Hydrogen Breath Test

Also known as: breath test, small intestinal bacterial overgrowth hydrogen breath test.

What is a hydrogen breath test?

If a doctor suspects that a patient is experiencing digestive problems where food is not being digested properly, he or she may order a hydrogen breath test.

Hydrogen is produced by bacteria in the digestive tract. If a large amount of hydrogen is detected by the hydrogen breath test, it’s an indication that a large amount of unabsorbed food has reached the intestines.

What happens during the procedure?

After fasting for 12 hours, a patient fills a balloon using their breath. Then the patient consumes a test sugar such as lactose and glucose or lactulose which is a non-absorbable sugar, and repeats the test every 15 minutes for several hours.

Is any special preparation needed?

The patient needs to avoid eating for 12 hours before the hydrogen breath test.

What are the risk factors?

There are no risks related to the hydrogen breath test.

Reviewed by: Carrie Firestone Baum, MD

This page was last updated on: 9/16/2025 12:41:16 PM

Gastroenterology

The Division of Pediatric Gastroenterology at Nicklaus Children's Hospital is dedicated to the treatment of a wide variety of gastrointestinal problems in infants, children and adolescents with a multidisciplinary approach. 

Learn More
Check Your Symptoms
Use the symptom checker tool to check how serious your symptoms are, if a healthcare visit is needed, and what steps you can take to relieve your symptoms at home.

Learn more about

Functional Abdominal Pain Many forms of abdominal pain are related to problems with the digestive function of the intestinal tract; inflammation within the lining of the intestinal tract; or blockages or other abnormalities in the structure of the intestinal tract or its associated organs.
Pancreatitis Pancreatitis is an inflammation of the pancreas. The pancreas is an abdominal organ found in the upper part of the abdomen which plays an important role in digestion and controlling the body’s blood sugar.
Lactose Intolerance Test This test is used to determine if a child is intolerant to milk or other products containing lactose. Early detection can prevent unnecessary discomforts and can be treated with adequate diet.