What precautions should i take before taking a blood stool test?

Food: Some fruits contain chemicals that prevent the guaiac, the chemical in which the test paper is soaked, from reacting with the blood. Aspirin and some nsaids irritate the stomach, resulting in bleeding and should be avoided prior to the examination, along with red meat and many vegetables and fruits containing vitamin c. All of these factors could result in a false-positive test.

Avoid red meat: The tests are very sensitive for blood in your stool and if you eat red meat it may be a false positive as the "blood" would be from the red meat and not your bowels.