What causes green stool?

Green stool can occur due to a normal or benign condition and not be a cause for concern. For example, you may produce green stool after consuming certain iron-rich foods or iron supplements, leafy green vegetables, or products with green food coloring

Additionally, a newborn baby will normally pass thick, sticky and dark green stools (called meconium) for the first few days after birth. Breast-fed babies may also have greenish stool.

Green stool can also be a symptom of various intestinal disorders that interfere with the normal digestion process, such as Salmonella food poisoning. As food passes through the digestive system, a yellow-green fluid called bile that helps digest food changes color, resulting in a stool that is light to dark brown. However, when an infection such as Salmonella causes diarrhea, food and feces pass through the digestive tract quickly before changing to a brown color.

Disease-related causes of green stool

Green stool can be caused by the following diseases:

  • Bacterial infection

  • Celiac disease (severe gluten intolerance that damages the small intestine )

  • Eating disorder, such as binge eating and abusing laxatives

  • Giardia (protozoan infection)

  • Intestinal cancer

  • Irritable bowel syndrome (IBS; digestive discomfort that does not cause intestinal damage or serious disease)

  • Pseudomembranous colitis (often due to overgrowth of C. difficile bacteria after a course of antibiotics for another bacterial infection)

  • Salmonella or E. coli food poisoning

  • Viral gastroenteritis (stomach flu)

Medication- and food-related causes of green stool

Green stool can be caused by supplements and other ingested substances including:

  • Breast milk

  • Certain antibiotics, which can lead to antibiotic-associated diarrhea and progress to pseudomembranous colitis

  • Eating green crayons

  • Green food coloring, such as those in drinks or popsicles

  • Iron supplements

  • Laxatives

  • Leafy green vegetables, which are rich in iron

Questions for diagnosing the cause of green stool

To diagnose the underlying cause of green stool, your doctor or licensed health care practitioner will ask you several questions related to your symptoms. You can best help your health care practitioner in diagnosing the underlying cause of green stool by providing complete answers to these questions:

  • When did the green stool start?

  • What is the color, texture and frequency of your bowel movements?

  • What medications, vitamins and supplements are you taking?

  • Do you have any other symptoms?

What are the potential complications of green stool?

Green stool can be normal, but it can also be caused by a serious intestinal infection or other disorder. It is important to contact your health care provider when you develop a persistent color change in your stool. Once the underlying cause is diagnosed, following the treatment plan that you and your health care provider design specifically for you can help reduce any potential complications including:

  • Dehydration from loss of fluids

  • Low potassium levels

  • Malabsorption syndrome

  • Malnutrition


  1. Diarrhea. National Digestive Diseases Information Clearing House (NDDIC). http://digestive.niddk.nih.gov/ddiseases/pubs/diarrhea/.

What is green stool?

Green stool is a condition in which the feces have a green coloring or tint. Green stool may be normal in some cases, such as in breast-fed infants. Green stool can also be caused by taking iron supplements or eating certain foods such as green leafy vegetables. Green stool can also indicate a problem with food digestion due to a disease, disorder or other abnormal process.


What other symptoms might occur with green stool?

Green stool may be accompanied by other symptoms, which vary depending on the underlying disease, disorder or condition. Symptoms that may accompany green stool include:

Medical Reviewer: Cynthia Haines, MD Last Annual Review Date: Aug 2, 2013 Copyright: © Copyright 2014 Health Grades, Inc. All rights reserved. May not be reproduced or reprinted without permission from Health Grades, Inc. Use of this information is governed by the HealthGrades User Agreement.

This Article is Filed Under: Digestive System

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