Stool color: When to worry

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  • With Mayo Clinic gastroenterologist

    Michael Picco, M.D.

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Mayo Clinic Health Manager

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Question

Stool color: When to worry

Yesterday, my stool color was bright green. Should I be concerned?

Answer

from Michael Picco, M.D.

Stool comes in a range of colors. All shades of brown and even green are considered normal. Only rarely does stool color indicate a potentially serious intestinal condition.

Stool color is generally influenced by what you eat as well as by the amount of bile — a yellow-green fluid that digests fats — in your stool. As bile pigments travel through your gastrointestinal tract, they are chemically altered by enzymes — changing the pigments from green to brown.

Consult your doctor if you're concerned about your stool color. If your stool is bright red or black — which may indicate the presence of blood — seek prompt medical attention.

Stool colorWhat it may meanPossible dietary causes
Green Food is moving through the large intestine too quickly, such as due to diarrhea. As a result, bile doesn't have time to break down completely. Green leafy vegetables, green food coloring, such as in Kool-Aid or popsicles, iron supplements.
Light-colored, white or clay-colored A lack of bile in stool. This may indicate a bile duct obstruction. Certain medications, such as large doses of bismuth subslicylate (Kaopectate, Pepto-Bismol) and other anti-diarrheal drugs.
Yellow, greasy, foul-smelling Excess fat in the stool, such as due to a malabsorption disorder. Sometimes the protein gluten, such as in celiac disease. But see a doctor for evaluation.
Black Bleeding in the upper gastrointestinal tract, such as the stomach. Iron supplements, bismuth subsalicylate (Kaopectate, Pepto-Bismol), black licorice.
Bright red Bleeding in the lower intestinal tract, such as the large intestine or rectum. Red food coloring, beets, cranberries, tomato juice or soup, red Jell-O or Kool-Aid.

AN00772

Feb. 5, 2008

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