The breath test uses radioactive carbon to detect H. pylori. To perform this exam, the person is asked to drink a tasteless liquid that contains the carbon as part of the substance that the bacteria breaks down. After an hour, the person is asked to blow into a sealed bag. If the person is infected with "H. pylori", the breath sample will contain radioactive carbon dioxide. This test provides the advantage of being able to monitor the response to treatment used to kill the bacteria.