November 25, 2015
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Stool Color Changes (cont.)

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What are symptoms of stool color changes?

Changes in stool color alone do not cause symptoms. The underlying cause of the change in stool color, texture, or form is responsible for any symptoms.

What are the causes of stool color, texture, and form changes?

In most cases, stool color changes are not symptoms of disease. Changes in stool color may be due to:

  • Diarrhea may cause green or yellow stools.
  • Some foods (beets, Jell-O, licorice)
  • A few OTC and prescription medications
  • Diseases affecting the liver, pancreas, and intestines

Green stools

If stool passes through the intestine too quickly, there might not be enough time for bile to be digested and broken down to provide the normal brownish stool color. Bile that is chemically changed by bacteria in the intestine can be greenish-brown. It takes time for the bile to be fully changed in the intestine and become brown again, and if the transit time is short, the stool remains green colored.

Green stools may be a normal variant. It can also be caused by a diet rich in green vegetables, especially spinach. Iron supplements also may be a cause, though iron often turns stool black.

Yellow, greasy, and foul smelling stool

There are a variety of reasons why stool will be yellow, greasy, and foul smelling. It can be due to the intestine's inability to digest and absorb fat because of diseases of the intestinal lining (such as in celiac disease and cystic fibrosis) because the pancreas is unable to manufacture adequate digestive enzymes (such as with chronic pancreatitis or pancreatic cancer that blocks the pancreatic duct, or there is not enough bile being delivered to the intestine (such as in cancer of the liver or bile ducts that block delivery of bile to the intestine). The yellowness, greasiness, and foul smell is due to the undigested fat.

Bright red stools

The most common cause of bright red stool is bleeding from hemorrhoids, but other bleeding causes are much more significant. For that reason, blood in the stool should never be ignored. Other causes include infections of the intestines, inflammatory bowel disease (Crohn's disease, ulcerative colitis), diverticular bleeding, tumors, and arteriovenous malformations (abnormal communications between arteries and veins in the wall of the intestine that rupture). Brisk bleeding from the upper GI tract may cause stools to be red instead of black if there has not been enough time for the red blood cells to be digested. Red food coloring and beets can also give a reddish hue to the stool.

Medically Reviewed by a Doctor on 9/16/2015


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