green stool

Green stool usually means that food has passed through the intestines faster than normal before it could be changed from green to brown. As bile pigments are added to digested food and move through your gastrointestinal tract, they are chemically altered by enzymes, changing the pigments from green to brown. When food passes through the intestines faster than normal, it is called decreased bowel transit time or rapid transit.

Consult your doctor if you’re concerned about your stool color. If your stool is bright red or black seek medical attention immediately. Black or red stool could indicate internal bleeding.


One of the main causes of green stool is diarrhea. Diarrhea decreases bowel transit time needed to change stool from green (the original color) to brown.

Other causes include:

Foods and supplements that can cause green stool include:

  • chlorophyll (especially chlorella and spirullina supplements)
  • iron supplements
  • algae

Green Stool in Breast-fed babies

In breast-fed babies, green stool is a normal occurrence, especially right after birth.

What to do if your stool is green

If you have green stool with other symptoms and cannot think of a reason why your bowel movements may have changed, call your doctor. While green stool is not considered abnormal, serious or chronic changes in bowel movement may indicate a cause for concern.

Questions to ask your doctor

  • Is green stool normal?
  • Can green stool be caused by medications?
  • Do I need to take medicine to get rid of the green stool?
  • Can green stool be caused by food?
  • How do I treat green stool?
  • What can I do to prevent green stool?
  • What should I do if I notice green stool?
  • Is green stool dangerous and will it hurt me?
  • Do I need to change my diet?
  • Will CBD help?
  • How long will green stool last?

Why is stool brown? 

The liver constantly secretes a bright green fluid called bile into the small intestine or it is stored in the gallbladder.

Bile is needed to absorb fats and fat soluble vitamins. Bile also helps to soften stools and is responsible for giving stools their characteristic brown color.

As bile makes its way through the intestines, it progressively changes color from green to yellow to brown. The color change is caused by the action of bacteria in the large intestine on the bile salts.

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