What causes green stool (feces)?

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Last updated: May 13, 2025View editorial policy

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Differential Diagnosis for Green Poop

  • Single most likely diagnosis
    • Bile pigment: Green poop can be caused by the presence of bile pigments in the stool, which is a common and harmless condition. This occurs when bile is not fully absorbed in the intestines, giving the stool a greenish color.
  • Other Likely diagnoses
    • Viral gastroenteritis: Certain viruses, such as norovirus, can cause green poop due to the rapid transit of stool through the intestines, which doesn't allow for the complete breakdown of bile pigments.
    • Food coloring or dyes: Consuming foods or drinks with green food coloring can temporarily turn the stool green.
    • Iron supplements: Iron supplements can cause green or black stools due to the oxidation of iron.
  • Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
    • Intussusception: A rare condition where a part of the intestine telescopes into another part, which can cause green or bloody stools. This condition requires immediate medical attention.
    • Bowel obstruction: A blockage in the intestines can cause green or bloody stools, and if left untreated, can lead to severe complications.
    • Inflammatory bowel disease (IBD): Conditions like Crohn's disease or ulcerative colitis can cause green stools due to inflammation and bleeding in the intestines.
  • Rare diagnoses
    • Giardiasis: A parasitic infection that can cause green, frothy stools, although this is relatively rare in developed countries.
    • Malabsorption disorders: Certain conditions, such as celiac disease or pancreatic insufficiency, can cause malabsorption of nutrients and bile pigments, leading to green stools.
    • Pseudomembranous colitis: A rare condition caused by an overgrowth of Clostridioides difficile bacteria, which can cause green or bloody stools.

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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