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Digestive Disorders > Symptoms

What does the color of my stool mean?

Elizabeth Oliver, PhD

Elizabeth Oliver, PhD

Stool consists of waste products that are eliminated from the body. The color of stool is usually related to what we eat and can range widely.

Because our diet often varies daily our stool color can also vary between each bowel movement. This means that changes in the color of your stool is rarely a reason to worry.

Occasionally, variations in stool color can be the first sign of a more serious health problem. Common causes for the different colors of stool are described below.

Stool color Possible causes (dietary or other) Should you see your healthcare provider?
Red stool
  • Beets, red wine, food coloring
  • Bleeding in the lower intestinal tract such as the large intestine or rectum
If you suspect blood in the stool, consult your physician
Black stool
  • Blueberries, charcoal tablets, iron supplements
  • Bleeding in the upper gastrointestinal tract such as the stomach
Yes, if changes can’t be explained by food or medication.
Dark brown stool
  • Increased meat consumption
  • Low fluid intake
Usually harmless
Yellow stool
  • Antibiotics, dairy products
  • Inability to digest or absorb fat
Yes, if changes persist for several weeks or can’t be explained by food or medication.
White stool
  • Bismuth-based medications
  • Lack of bile
Green stool
  • Spinach, broccoli
  • Bacterial infection (e.g. by salmonella)
Yes, if accompanied by diarrhea
Orange stool
  • Carrots
Usually harmless

How does stool get its color?

Stool color is influenced by what you eat as well as the amount of bile that is present in your stool. Bile is a yellow-green fluid which helps you to digest fats. Bile gets its color from two pigments called bilirubin and biliverdin which are produced by the breakdown of red blood cells. As the bile pigments travel through the digestive tract they become chemically altered by enzymes and change from green to brown, giving your stool its characteristic color.

What is the color of normal stool?

Stool comes in a range of different colors. All shades of brown and even green are considered normal. Certain foods or medications can lead to various changes in stool color. Once you eliminate these foods or medications from your diet your stool color should return to normal.

What does red stool mean?

Red stool can be alarming, but it is not always a reason to be worried. Uniformly red-colored stool can be caused by a variety of different foods including beets, red wine, and cranberries.

Red stools can also be caused by fresh blood. Red blood is typically a result of bleeding in the lower digestive system, such as from the rectum or colon. As blood from lower in the gastrointestinal system is exposed to less of the digestive process, it keeps its bright red color. Common causes include:

  • Hemorrhoids, anal tears, and fissures
  • Chronic inflammatory bowel disease (ulcerative colitis or Crohn’s disease)
  • Inflammation of the rectum, known as proctitis
  • Diverticulosis, which is inflammation of small pouches known as diverticula that can form on the colon

If you are unable to trace your red stool back to food that you have recently eaten, consult your physician for advice.

What does black stool mean?

Black stool may be caused by certain foods such as blueberries and licorice, as well as some medicines including iron supplements and bismuth-based medication.

Bleeding in the upper digestive tract can also cause black or tarry stools. Bleeding can occur in the esophagus, stomach, or duodenum. When the blood comes into contact with stomach acid or digestive fluids, the red blood cells break down, resulting in a dark tar-like appearance. Some causes of upper gastrointestinal bleeding include:

  • Stomach ulcer
  • Ruptured esophageal varices (large veins in the esophagus or stomach)
  • Gastric cancer

If you suspect you have blood in your stool, contact your physician to rule out any serious medical conditions.

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What does yellow stool mean?

Yellow-brown stool color is usually harmless and can be attributed to diet. The consumption of milk, starchy products, and eggs can cause stool to turn yellow and is typical in infants who are breast-fed. Medications such as antibiotics can also turn bowel movements yellow.

Yellow stool that appears in conjunction with diarrhea is most likely caused by a bacterial or viral infection such as gastrointestinal influenza. Antibiotics can also result in yellow diarrhea.

If yellow bowel movements become regular or are accompanied by other symptoms, it may suggest an underlying problem.

Light-yellow greasy stool with an unpleasant odor is known as steatorrhea. Steatorrhea, or fatty stool, is a result of excess fat in your stool. It occurs because the body is unable to digest or absorb fats and so excretes them instead. This can be a result of a malabsorption disorder, such as celiac disease, an enzyme deficiency, or gastrointestinal disease. Fatty bowel movements often float in the toilet. If this problem persists for an extended time it may lead to weight loss.

What does gray-white stool mean?

Pale colored stool can be caused by bismuth-based medications used to treat diarrhea. The chalky liquid contrast barium which is required for certain medical examinations can lead to almost white stool. Your stool will return to its normal color once all the barium has been expelled.

White or clay-like stool can also be caused by a lack of bile. Bile is produced by the liver and stored in the gallbladder. Bile is released into the intestine during digestion and gives stool its characteristic brown color. If the liver doesn’t produce bile or bile is obstructed from leaving the liver the stool will be light colored or white.

Additional symptoms can include:

  • Dark urine
  • Yellowing of the skin and eyes (jaundice)
  • Itching (pruritus)

Possible causes include diseases of the biliary tract, the liver, gallbladder, bile ducts, or the pancreas.

What does green stool mean?

Diet is the most common reason for green stool. Dark green vegetables such as kale, spinach and broccoli contain a lot of chlorophyll, which can turn the stool green.

Diarrhea can also lead to green stool. Diarrhea causes food to move rapidly through the large intestine and as a result the green-yellow colored bile doesn't have time to break down completely. Diarrhea can be caused by bacterial or viral infections as well as gastrointestinal conditions such as irritable bowel syndrome and ulcerative colitis. Overuse of laxatives can also lead to green stool.

What does orange stool mean?

A large amount of carrots or squash may result in an orange coloration of the stool. This is not dangerous.

What to do if my stool is discolored?

Most one-off changes in stool color are likely to be caused by diet. If the color change becomes frequent or is accompanied by additional symptoms you should consult your healthcare provider who will be able to evaluate your symptoms and investigate further. If you suspect you have blood in your stool you should always seek medical advice immediately.

Floch MH. Netter's Gastroenterology E-Book. Elsevier Health Sciences; 2019 Jan 18

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Bekkali N, Hamers SL, Reitsma JB, Van Toledo L, Benninga MA. Infant stool form scale: development and results. J Pediatr. 2009;154(4):521-526.e1. doi:10.1016/j.jpeds.2008.10.010

Tseng J-J, Lai M-S, Lin M-C, Fu Y-C. Stool Color Card Screening for Biliary Atresia. Pediatrics. 2011;128(5):e1209-e1215. doi:10.1542/peds.2010-3495

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Elizabeth Oliver, PhD

Elizabeth Oliver, PhD

Elizabeth Oliver is a researcher and freelance writer with a passion for health sciences. She completed her degree in pharmacology at the University of Edinburgh and PhD in reproductive health at Imperial College London. She currently works as a researcher at the Karolinska Institutet Stockholm.

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