 [ Symptoms ] is there a simple inexpensive way to remove small round black and brown beauty marks [ Disease ] black stools could indicate blood but it can also mean that you have been taking pepto bismol the bismuth in this medication causes that stools to be blackish red like stools do not necessarily mean blood but it could be there are special stool tests that will test for the presence of occult hidden blood that should be done four weeks of diarrhea does require a thorough work up so i am glad that this is being done