In some cases, an unusual stool color is harmless and can be attributed to a particular food or medication -- but not always. Changes in bowel habits that persist can be a serious matter and should always be investigated by a physician.
Black Or Red Stool
Black or red stools can indicate internal bleeding somewhere in the gastrointestinal tract. Stool that contains blood from the upper digestive tract is black, tarry, has a distinctive odor, and is known as "melena." Stool that is red in color because it contains blood is called hematochezia. In the case of hematochezia, blood may coat the stool, be mixed in with the stool, or even be passed without any stool at all.
Causes of black colored stools include:
- acidified blood (blood from higher in the digestive tract)
- iron supplements or foods high in iron
- Pepto-Bismol or other medicines containing bismuth
- black licorice
- large amounts of spinach or other greens
- other foods dark in color
Causes of red colored stools include:
- blood (such as from hemorrhoids, anal fissures, or diverticualr disease)
- red gelatin, popsicles, or food containing artificial red coloring
- tomato juice or soup
- large amounts beets
Pale Or Clay-Colored StoolCauses of pale or clay colored stools include:
- liver disease (such as hepatitis or obstruction of bile ducts)
- antacids containing aluminum hydroxide
- barium from a recent barium enema test
Green StoolCauses of green stools include:
- large amounts of green, leafy vegetables
- green or purple artificial coloring (popsicles, Kool-Aid, gelatin)
- iron supplements
- infectious gastroenteritis
- rapid bowel transit or decreased colonic transit time
Orange StoolCauses of orange colored stools include:
- some medications (such as beta-carotene and Rifampen)
- foods high in beta-carotene: carrots, sweet potatoes, apricots, winter squash, pumpkin, cantaloupe, and mangoes
National Institute of Diabetes and Digestive and Kidney Diseases. "Bleeding in the Digestive Tract." National Digestive Diseases Information Clearinghouse. November 2004. 22 Apr 2009.
A.D.A.M. Health Illustrated Encyclopedia. "Bloody or tarry stools." A.D.A.M. 25 July 2007. 22 Apr 2009.
A.D.A.M. Health Illustrated Encyclopedia. "Stools - pale or clay-colored." A.D.A.M. 8 Aug 2008. 23 Apr 2009.