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Green Stool

What it Means When Your Poop is Green

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Updated March 21, 2014

green stool Peter Cade/The Image Bank/Getty Images

It may be alarming to see green stool (or other types of unhealthy stool) in the toilet but there are some common reasons why it occurs. 

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

Bile plays a role in the emulsification, absorption, and digestion of fat and fat soluble vitamins. It helps to soften stools and is responsible for giving stools their characteristic brown color. Bile helps to alkalinize the contents of the intestines. It is made up of bile salts, cholesterol, phospholipids, bilirubin, and electrolytes.

As bile makes its way through to the small intestine and then to the large intestine via the bile ducts, it progressively changes color from green to yellow to brown, due to the action of bacteria in the large intestine on the bile salts.

Green stool often indicates that food has passed through the intestines faster than normal (called decreased bowel transit time), before it could be changed from green to brown. Diarrhea decreases bowel transit time so any condition that causes diarrhea can result in green stool.

Conditions that can cause green stool include:

  • Laxative use (e.g. OTC laxatives, insoluble fiber or senna, cascara sagrada, rhubarb
  • Food poisoning
  • Celiac disease
  • Watery diarrhea due to Clostridium difficile (typically after antibiotic use) 
  • Medication side effects (e.g. ciprofloxacin, lexapro, nyquil, zantac)
  • Ulcerative colitis
  • Crohn's disease
  • Malabsorption
  • Irritable bowel syndrome
  • Bacterial overgrowth
  • Infectious diarrhea - especially Salmonella and Giardia
  • Traveler's diarrhea
  • Cancer
  • Graft versus host disease
  • Alcohol consumption - ethanol stimulates bowel motility

In some cases, soluble fiber can be increased in the diet to slow transit time. You can get soluble fiber naturally through food such as oats, legumes (peas and other beans), rye, barley, certain fruits and vegetables (prune juice, plums, bananas, berries, carrots, the insides of apples and pears, root vegetables, psyllium seeds. Also see Natural Remedies for Diarrhea for three ways to address diarrhea naturally. 

Food, dyes and supplements that can cause green stool include: 

  • Spinach, kale and other green vegetables
  • Blueberries
  • Juicing with green vegetables or fruits or during a juice fast.
  • Green or purple food coloring in drink mixes, frozen ice pops, cake icing, blue Gatorade, packaged fruit snacks and other foods.
  • Grape-flavored Pedialyte may turn stools bright green.
  • Foods that contain the green pigment chlorophyll can also cause temporarily green stool, including algae and grasses such as wheatgrassspirulinabarley grass, seaweed and chlorella.
  • Nutritional supplements that contain chlorophyll such as greens powder. 
  • Iron supplements and iron-enriched products including baby formula are another cause of green stool. 

When these foods, dyes and supplements are withdrawn from the diet, stool should return to its normal color within a day.

An infant's first bowel movements are typically green-black in color. This is called "meconium" - you should not see it after the infant is three days old. 

Disclaimer: The information contained on this site is for educational purposes only and should not be used as a substitute for diagnosis or treatment. It is essential that you discuss with your doctor any symptoms or medical problems that you may be experiencing.

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