The carbon 14 breath test is a test set up to check for H. pylori infection in the stomach, and fasting is recommended prior to the test. In addition, antibiotics should be stopped within four weeks before the test, and acid-suppressing drugs should be stopped two weeks before the test to avoid false-negative results. In addition, the carbon 14 breath test is radioactive, so children or pregnant women, or women of childbearing age who are planning to become pregnant, are advised not to complete this test, but to consider the carbon 13 breath test to determine the presence of H. pylori infection.