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:
Maroon-colored stolls or bright red blood often men that the blood is coming from the small or large bowel, rectum, or anus. The term "hematochezia" is used to describe this finding.
Abnormal blood vessels
When blood supply is cut off to part of the intestines, called Bowel inschemia
Call your doctor right away if you notice blood or changes in the color of your stool. You should be examined by your doctor even if you think that hemorrhoids are causing the blood in your stool.
In children, a small amount of blood in the stool is usually not serious. The most common cause is constipation. You should still tell your child's doctor if you notice this problem.
Your doctor will take a medical history and perform a physical exam that focuses on your abdomen and rectum.
You may be asked the following questions:
You may need to have one or more tests to look for the cause:
Reviewed By: 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.