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, the blood may coat the stool, be mixed in with the stool, or even be passed without any stool at all.
Potential 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
Potential 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 StoolPotential causes 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 StoolPotential causes 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 StoolPotential causes 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
If a change in stool color cannot be attributed to a dietary reason, or is accompanied by any other symptoms (such as diarrhea, constipation, weakness, or dizziness), a doctor should be consulted. Frank blood in the stool, or passing blood with no stool should be reported to a physician as soon as possible.
Dugdale DC. "Stools - pale or clay-colored." A.D.A.M. 2 Sept 2012. 4 Sept 2013.
Heller JL. "Bloody or tarry stools." A.D.A.M. 7 Jan 2011. 4 Sept 2013.
National Institute of Diabetes and Digestive and Kidney Diseases. "Bleeding in the Digestive Tract." National Digestive Diseases Information Clearinghouse. November 2004. 6 Aug 2013.