Stool Color & Medical Diagnosis

A medical diagnosis can be determined through stool colour. Stool is typically brown, but bowel movement colours can vary. However, just because a person's stool colour isn't brown doesn't mean he is not healthy.

Bowel Movement Colors

Bowel movements can be red, black, yellow, green and whitish/clear. Black, red and yellow are less healthy stool colours.

Red Stool Color

The shade of red stool determines the medical diagnosis. Bright red is an indicator of hematochezia; a simple type of rectal bleeding. The darker the red the more serious the medical diagnosis is likely to be. Dark red stool can indicate stomach or colon cancer.

Black Bowel Movements

Stool that appears black is a very bloody stool. Black stool will likely lead to the medical diagnosis of a bleeding ulcer.

Yellow Bowel Movements

Yellow bowel movements may indicate Celiac disease, an inherited intolerance for foods with gluten. Gluten is a protein found in grains like wheat, barley and rye which are used in cakes, breads and muffins. Yellow, oily bowel movements indicate the body is not properly digesting fats.

Colours in Relation to Diet

Green and yellow stool colour can be linked to diet. Yellow stool colour indicates too much fat in the diet. Green bowel movements can be caused by eating green foods like spinach and lettuce or foods with green dyes like Popsicles. Additionally, green bowel movements can be caused by travelling through the gastrointestinal tract too fast.


Stool colour may be affected by any medication a person is taking. Medications can reduce the amount of bile (fluid that digests fats) in the waste. As a result, stool may turn a whitish colour.

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About the Author

Zachary Fenell is a 2009 graduate of Notre Dame College of Ohio. He holds a Bachelor of Arts in communication with minors in philosophy and writing. Fenell has been writing since 2002, when he joined his high school newspaper, "The Arc Light." In college Fenell won awards for excellence in English and communication.