Bloody stools often are a sign or a problem in the digestive tract. Blood in the stool may come from anywhere along your digestive tract from your mouth to your anus.
Stools - bloody; Hematochezia; Melena; Stools - black or tarry
Heavy or rapid bleeding in the upper GI tract can cause bright red stools.
Eating black licorice, lead, iron pills, bismuth medicines like Pepto-Bismol, or blueberries can also cause black stools. Beets and tomatoes can sometimes make stools appear reddish. In these cases, your doctor can test the stool with a chemical to rule out the presence of blood.
Bleeding in the esophagus or stomach (such as with peptic ulcer disease) can also cause you to vomit blood.
Bleeding that takes place in the esophagus, stomach, or the first part of the small intestine most often causes the stool to appear black or tarry. Your doctor may use the term "melena."
Bleeding in the upper part of the GI tract will usually cause black stools due to:
Abnormal blood vessels
A tear in the esophagus from violent vomiting (Mallory-Weiss tear)
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David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by A.D.A.M. Health Solutions, Ebix, Inc., Editorial Team: David Zieve, MD, MHA, Bethanne Black, Stephanie Slon, and Nissi Wang.