What is a 'normal' stool color?
The normal color of stool is brown, which is due to a substance called bilirubin found in bile. When the color of your stool changes, it is often harmless and may be due to dietary choices. However, persistent changes in the color and smell of your stool could be caused by gastrointestinal (GI) bleeding.
What stool colors may indicate health problems?
- Black stool: This is usually foul-smelling and is caused by upper intestinal bleeding (stomach or upper small intestine, ulcers, or tumors. It may also be caused when you take iron supplements or bismuth (Pepto Bismol).
- Maroon or purple stool: This is caused by intestinal bleeding (usually in the small intestine or first part of the colon), ulcers, tumors, Crohn's disease, ulcerative colitis, or infections.
- Bright red stool: This occurs when bright red blood gets mixed with or covers the stool as it passes through the rectum. This is caused by hemorrhoids, colon polyps, rectal fissures, massive gastrointestinal bleeding, or colon cancer.
There is considerable overlap in the appearances of the stool when dealing with a gastrointestinal bleeding episode. Any changes in the color of your stool or evidence of bleeding in your bowel movements needs to be evaluated by your physician. If stool color changes are associated with abdominal pain, fever, lightheadedness or passing out, weakness, palpitations, or if you are taking blood thinners, seek emergency care.
Medically reviewed by Avrom Simon, MD; Board Certified Preventative Medicine with Subspecialty in Occupational Medicine
UpToDate. Major causes of upper gastrointestinal bleeding in adults.