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Dark colored stools
Stools are produced in the intestines and are the end product of the digestive system. When we consume food, it passes from our stomach into o...

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Dark colored stools are bowel movements that are a deeper (usually black, dark green or maroon) color rather than the usual brown color.

Alternative Names

Dark color feces.


Stools are produced in the intestines and are the end product of the digestive system. When we consume food, it passes from our stomach into our intestines. Dark colored stools (black, maroon or red) may be a sign of blood in the stool. See the Health Article Bloody or tarry stools for more information. Ingesting certain foods or substances can turn the stools dark. Iron supplements, Pepto-Bismol and blueberries can cause the stools to turn black. Beets can cause the stools to turn deep red. Spinach and chard can cause the stools to turn deep green.

Dark colored stools can also be indicative of a disease. If you have not consumed any substance that might affect the color of your stool, and the dark color persists, seek medical attention.

Associated Diagnoses

  • Alcoholic liver disease
  • Anal fissure
  • Anthrax
  • Bleeding esophageal varices
  • Cancer of the colon
  • Trauma
  • Cancer of the esophagus
  • Celiac disease
  • Colitis
  • Crohn’s disease
  • Diverticulitis
  • Enteritis
  • Hemorhoids
  • E. coli infection
  • Necrotizing enterocolitis
  • Thalessemia
  • Peptic ulcer
  • Polyp of large intestine
  • Stomach cancer
  • Stomach ulcer

Diagnosis and Treatments

A comprehensive evaluation by a physician is necessary when dark colored stools that are not due to ingesting a particular food are present. Treatment will depend on accompanying symptoms and the diagnosis. Diagnostic studies might include colonoscopy, stool culture, x-rays, blood tests, barium studies, fecal occult blood testing and flexible sigmoidoscopy.

The American Cancer Society recommends the following screening tests after age 50 for colon cancer. Screening should begin at an earlier age if there is a family history of colon cancer:

  • Fecal occult blood testing annually
  • Flexible sigmoidoscopy or barium enema every 5 years
  • Colonoscopy every 10 years

Call your provider:

Any change in the color of bowel movements that is not known to be due to eating a certain food or medication should be reported to your doctor. Report blood in the stool to your doctor immediately.

Written by: JC Jones MA, RN
Reviewed by: Paul Auerbach, MD
Written: November 6, 2007
Last Updated: November 30, 2007
Published By: Healthline Networks Inc.
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