Hydrogen Breath Test

  • Medical Author:
    Jay W. Marks, MD

    Jay W. Marks, MD, is a board-certified internist and gastroenterologist. He graduated from Yale University School of Medicine and trained in internal medicine and gastroenterology at UCLA/Cedars-Sinai Medical Center in Los Angeles.

  • Medical Editor: William C. Shiel Jr., MD, FACP, FACR
    William C. Shiel Jr., MD, FACP, FACR

    William C. Shiel Jr., MD, FACP, FACR

    Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.

Are there other ways in which hydrogen breath testing can be used?

Antibiotics are used for treating bacterial overgrowth of the small bowel; however, any one antibiotic may be effective at eliminating the overgrowing bacteria only 50%-60% of the time. Therefore, if symptoms do not disappear in an individual following treatment with antibiotics, it may be useful to repeat the breath test to determine if the antibiotics have eliminated the bacteria. If not, a different antibiotic or non-antibiotic treatment can be tried.

What are the side effects of hydrogen breath testing?

The side effects of hydrogen breath testing are exactly what one would expect to see in individuals who poorly digest and absorb sugars and carbohydrates, for example, bloating, distention, pain, and diarrhea. When lactulose is used these symptoms are unlikely to occur or are mild because the dose of lactulose used for testing is small.

What are the alternatives to hydrogen breath testing?

For diagnosing lactose intolerance, an alternative procedure to breath testing requires blood samples to be taken after the ingestion of lactose. If the digestion and absorption of lactose is normal, the levels of glucose in the blood should rise. The elevation of blood glucose occurs because the lactose is broken down into its two component sugars, galactose and glucose, as it is absorbed into the blood. A second alternative is to give a dose of lactose (or other dietary sugar) and observe an individual for symptoms. If the individual is intolerant, bloating, distention, pain, flatulence, and diarrhea are likely to occur. A third alternative is a trial of a diet in which the potentially-offending sugar is strictly eliminated. All of these alternatives, however, have limitations and problems.

Bacterial overgrowth can be diagnosed by culturing (growing) the bacteria from a sample of fluid from the small intestine and counting the numbers of colonic bacteria that are present. This procedure requires a tube to be passed through the nose, throat, esophagus and stomach under X-ray guidance so that fluid can be obtained from the small intestine. It is an uncomfortable and expensive procedure, and most laboratories are not able to accurately culture the samples. Hence, this test is not performed routinely.

Medically reviewed by Avrom Simon, MD; Board Certified Preventative Medicine with Subspecialty in Occupational Medicine


"Use and abuse of hydrogen breath tests"
National Institutes of Health

Medically Reviewed by a Doctor on 9/2/2016

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