Why Is My Poop Dark Green?

Dark green poop can be surprising, but it’s not always a sign of something serious. Stool color can change for many reasons—from the foods you eat to how fast things move through your gut. Below, you’ll find clear explanations of common causes, when to worry, and what you can do next.

How Stool Color Works

• Bile pigments: Your liver produces bile to help digest fats. Bile starts out green, then changes to yellow and brown as it moves through your intestines.
• Transit time: The speed at which stool moves affects how much pigment is broken down. Faster transit can leave more green bile pigment intact.
• Diet and supplements: Things you eat or take can tint your stool.

Common Causes of Dark Green Poop

1. Diet and Food Coloring

   • Leafy greens: Spinach, kale, and other dark green vegetables contain chlorophyll, which can tint stool.
   • Artificial colors: Green candies, frostings, sports drinks, and gelatin snacks may pass color directly through your digestive tract.

2. Rapid Intestinal Transit

   • Acute diarrhea: When stool moves too quickly, there isn’t enough time for bile to turn brown. Infections and food intolerances often cause loose, greenish poops. (Foxx-Orenstein & McFarland, 2010)
   • Laxatives: Overuse of stimulant laxatives can speed up transit.

3. Bile Acid Malabsorption

   • Bile acid diarrhea: If your ileum (last part of the small intestine) can’t reabsorb bile properly, excess bile enters the colon and can produce green, watery stools. Symptoms may include urgency, cramping, and fatigue. (Walters & Pattni, 2006)
   • Causes: Inflammatory bowel disease (IBD), surgical removal of part of the ileum, or idiopathic (no known cause).

4. Infections

   • Bacterial: Salmonella, Shigella, Campylobacter
   • Viral: Rotavirus, norovirus
   • Parasitic: Giardia lamblia
     These can inflame the gut lining, speed transit, and cause greenish diarrhea. Look for fever, abdominal pain, or recent travel.

5. Medications and Supplements

   • Iron supplements: Can darken stool, sometimes with a greenish hue.
   • Antibiotics: May disrupt normal gut bacteria and produce green, loose stools.

6. Other Conditions

   • Celiac disease: Poor absorption and faster transit in untreated cases can alter stool color.
   • Post-surgery changes: Removal of part of the small intestine or gallbladder can affect bile flow.
   • Irritable bowel syndrome (IBS): Can cause alternating diarrhea and constipation, sometimes with greenish stools.

When to Be Concerned

Most causes of dark green poop are harmless and resolve on their own. However, see a doctor if you experience:

• Persistent green diarrhea for more than 48 hours
• Blood in stool or black, tarry stool
• Severe abdominal pain or cramping
• High fever (over 102°F/39°C)
• Signs of dehydration: dizziness, dry mouth, dark urine
• Unexplained weight loss
• Jaundice (yellowing of skin or eyes)

If you’re unsure how serious your symptoms are, consider doing a free, online symptom check to help decide your next steps.

What You Can Do Now

• Review your diet: Cut back on green veggies and artificial colorings for a day or two to see if stool color returns to normal.
• Stay hydrated: Especially if you have diarrhea. Aim for clear fluids, oral rehydration solutions, or broths.
• Monitor symptoms: Note stool consistency, color changes, frequency, any pain or fever.
• Avoid unnecessary laxatives or over-the-counter remedies unless directed by a healthcare provider.

Diagnosing the Cause

If green poop persists or you have alarming symptoms, a healthcare provider may recommend:

• Stool studies: To check for infection, blood, or malabsorption.
• Blood tests: To assess liver function, inflammation markers, or celiac disease antibodies.
• Imaging: Ultrasound or CT scan to look at your gallbladder, bile ducts, or intestines.
• Endoscopy or colonoscopy: If structural problems or inflammatory bowel disease are suspected.

Treatment Options

• Dietary changes: Eliminate trigger foods, adjust fiber intake, or follow a low-FODMAP plan for IBS.
• Medications:
  • Bile acid binders (e.g., cholestyramine) for bile acid diarrhea
  • Antibiotics or antiparasitics for confirmed infections
  • Probiotics to help restore healthy gut bacteria after antibiotics
• Management of underlying disease:
  • Gluten-free diet for celiac disease
  • Anti-inflammatory drugs or biologics for IBD
  • Surgery or stenting for obstructive conditions

Preventing Green Poop

• Eat a balanced diet: Include fruits, lean proteins, whole grains, and varied vegetables.
• Drink plenty of fluids: Helps maintain normal transit time.
• Practice good food safety: Wash produce, cook meats thoroughly, and avoid known allergens.
• Take medications as prescribed: Follow dosing guidelines for iron supplements, antibiotics, or bile acid binders.
• Manage stress: Stress can affect gut motility and trigger IBS symptoms.

When to Talk to a Doctor

If you experience any life-threatening or serious warning signs—high fever, severe pain, bloody stool, signs of dehydration, or unexplained weight loss—contact your doctor or go to the nearest emergency department right away. Always consult a healthcare professional before starting or stopping any medication.

Remember, while dark green poop is often harmless and temporary, you know your body best. If you’re concerned or your symptoms persist, speak to a doctor for personalized advice.