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My stool has changed color. What does it mean?

Medically reviewed by Carmen Fookes, BPharm. Last updated on Sep 8, 2019.

Official Answer

by Drugs.com

Your poop (stool) can come in a range of colors. All shades of brown and even green are considered normal.

The two main causes of poop color change are diet and conditions that change how fast food travels through our intestine. The speed that food travels through our intestine is important, because a substance that mixes with food, called bile, doesn't have enough time to break down if food is moving too fast through the intestine.

Bile is a yellow-green fluid produced by our liver and stored and released by our gallbladder. Anytime we eat food that contains fat, even a small amount of fat, a signal is sent to our gallbladder to release bile, which flows into the upper part of our small intestine through two small tubes (the cystic duct and common bile duct). As bile travels down our intestine it is chemically altered by enzymes, and the color changes from yellowish-green to brown. However, this process takes time and several different conditions can quicken intestinal transit time, meaning that bile retains some of its yellowish-green color.

The table below summarizes the most common color changes and possible reasons. Only rarely does stool color indicate a potentially serious intestinal condition. Generally, a color change accompanied by other symptoms, such as abdominal pain, diarrhea, cramps, weight loss, or fever should be investigated further. Bright red or black poop may indicate the presence of blood and you should talk to your doctor straight away.

Color Medical Causes Dietary Causes
Black stool
  • Bismuth subsalicylate (Kaopectate, Pepto-Bismol)
  • Bleeding within the GI tract (eg, from stomach ulcers)
  • Bowel ischemia
  • Cancer
  • Iron supplements
  • Varices
  • Vascular malformations
  • Blueberries
  • Dark chocolate
  • Iron supplements
  • Licorice
Blue/purple stool
  • Prussian blue (Radiogardase) – a medication used to move radioactive compounds from a person’s body
  • Porphyria
  • Blue food coloring
  • Blueberries/imitation blueberries
  • Blue drink mixes
  • Currants/raisins
  • Plums
Green stool
  • Crohn’s disease
  • Gall bladder disease
  • Infection (eg, E. coli, Giardia, Norovirus, salmonella)
  • Irritable bowel syndrome
  • Medications such as Depo-Provera (medroxyprogesterone birth control shot), indomethacin, iron supplements
  • Ulcerative colitis
  • Broccoli, green leafy vegetables, kale, spinach, wheatgrass
  • Iron supplements
  • Licorice
  • Green or black food coloring
Light-colored or clay-colored stool
  • Celiac disease
  • Gall bladder disease
  • Giardia
  • Lack of bile (eg, from a bile tract obstruction)
  • Large doses of anti-diarrhea drugs or bismuth subsalicylate (Kaopectate, Pepto-Bismol)
  • Liver disease
  • Pancreas disease
  • Gluten
  • Fatty foods
Red stool
  • Bleeding in the lower part of the digestive system
  • Cancer
  • Diverticulosis
  • Hemorrhoids
  • Ulcerative colitis/ Crohn’s disease
  • Worming medications
  • Beets
  • Cranberries
  • Red drink mixes
  • Red gelatin
  • Red food coloring
  • Sundried tomatoes
  • Tomato juice/soup
Yellow stool
  • Absorption disorders
  • Celiac disease
  • Infection
  • Liver and gall bladder disease
  • Pancreatic disorders
  • Carrots
  • Gluten
  • Sweet potatoes
  • Yellow food coloring

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