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Blood In Stool

Causes of Blood In Your Stool


Updated May 20, 2014

Written or reviewed by a board-certified physician. See About.com's Medical Review Board.

Seeing blood in the toilet or on the tissue after wiping can be frightening. Blood can range in a multitude of colors and also be caused by many different conditions. The important thing to do when you experience blood in your stool is to not panic and to see your doctor.

Is Blood In My Stools a Symptom of Cancer?

Most likely, the blood in your stool is related to a less serious condition. However, if bleeding is cancer related, colorectal cancer and anal cancer are two types of cancers that can cause rectal bleeding or blood to be present in the stool. It is important to note that precancerous conditions, like colon polyps, can cause rectal bleeding. BUT: Do not assume that because you have blood in your stool you have an advanced cancer.

If It's Not Cancer, What Could Be Causing Blood in My Stools?

When most people discover blood in their stool, it is most often caused by hemorrhoids or anal fissures. Other causes can include:

The color of the blood can also give insight into where the bleeding is coming from and help make a diagnosis. Bright red bleeding usually indicates bleeding from the rectum and lower end of the colon. Dark red, brown or black blood usually is caused by bleeding in the upper gastrointestinal tract.

Medications or foods can also alter the color of stools. Bismuth subsalicylate (Pepto Bismol) and Kaopectate can cause black stools following usage. Iron tablets and eating beets can also cause stool color changes that are not serious.

Seeing Your Doctor

It is important to see your doctor if you have blood in your stool. Do not assume that it is caused by hemorrhoids or anal fissures. While these are the most common culprit, you can't determine at home if it isn't polyps or another source that is the cause of the bleeding.


Bleeding in the Digestive Tract. National Digestive Diseases Clearinghouse. Nov. 2004. [http://digestive.niddk.nih.gov/ddiseases/pubs/bleeding/index.htm].

Blood in Stool. American Cancer Society. 7 Apr. 2008. [http://www.cancer.org/docroot/MBC/content/MBC_2_3x_Blood_in_Stool.asp?sitearea=MBC].

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