Stool Color Changes (cont.)
Benjamin Wedro, MD, FACEP, FAAEM
Benjamin Wedro, MD, FACEP, FAAEM
Dr. Ben Wedro practices emergency medicine at Gundersen Clinic, a regional trauma center in La Crosse, Wisconsin. His background includes undergraduate and medical studies at the University of Alberta, a Family Practice internship at Queen's University in Kingston, Ontario and residency training in Emergency Medicine at the University of Oklahoma Health Sciences Center.
Bhupinder Anand, MD
In this Article
Black tarry stools
Black stools are a worrisome symptom because it may be due to bleeding into the gastrointestinal tract, most often the esophagus, stomach or duodenum. Red blood cells are broken down by digestive enzymes and turn the stool black. These stools tend to be tarry and foul smelling. This can be a medical emergency; black tarry stools should not be ignored.
Blood from nosebleeds or from dental procedure and injuries can be swallowed and may be the cause of black stool.
Certain foods and medications can turn stool black, including iron, bismuth (Pepto Bismol, loperamide [Kaopectate]), beets, and licorice. While the stools may be black, they also tend to be gritty and not tarry. Pregnant women may have black stools due to prenatal vitamins, which contain iron.
Bright red stools
The most common cause of bright red stool is bleeding from hemorrhoids, but other bleeding causes are much more significant. For that reason, blood in the stool should never be ignored. Other causes include infection, inflammatory bowel disease (Crohn's disease, ulcerative colitis), diverticular bleeding, tumors, and arteriovenous malformations (AVM). Brisk bleeding from the upper GI tract may cause stools to be red instead of black because there has not been enough time for the red blood cells to be digested. Red food coloring and beets can also give a reddish hue to the stool.
Light-colored white or clay-colored stools
White or clay colored stool are often seen with liver or biliary tract diseases. Lack of bile which gives stool its brown color leaves it appearing pale.
Medically Reviewed by a Doctor on 6/18/2015
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