You’ve been told by your doctor that a hydrogen breath test is necessary for further evaluation of your medical condition. This noninvasive test measures the amount of hydrogen and methane produced in the small intestine after a person has ingested a dose of a form of sugar.  The test is called noninvasive because it does not involve the insertion of needles or other devices into the body.

The test involves breathing into a balloon-like bag. Some of the air will be removed and inserted into a machine to obtain a baseline reading. You will be asked to drink a glass of flavored solution. You will not be able to drink anything else during test. A timer will be set and you will be asked to breathe into the balloon every 30 minutes. Samples again will be inserted into the machine, and the hydrogen and methane levels will be evaluated. This routine may continue for up to four hours, depending upon the hydrogen values seen during the testing time. It is suggested that you bring videos, books, magazines, small crafts, etc., to entertain yourself during this procedure. The hospital also may have a TV or magazines for your use. 

Review these documents to help you prepare for your procedure: 
Hydrogen breath test instructions
Insurance information for hydrogen breath test