Q. When should you be concerned about changes in stool color?
Dr. Dave says: White or clay-colored stool, especially if you notice that your urine is dark too, is worth calling your doctor about. And blood in your stool can be potentially worrisome as well. What most people don’t know is that it looks different depending where the bleeding is coming from. Black and tar-like in consistency (not just really dark brown), or blood that’s dark and mixed into the stool so that it looks “marbled,” as well as bright red blood, tend to come from higher to lower, respectively, in your gastro-intestinal tract and are always worth a call to your doctor.