Green-Colored Stool
Green stool along with stomach pain could indicate an infection, whether bacterial, viral, or parasitic.

Changes in the color of the stool are a common symptom; however, persistent changes in the color could be a matter of concern. The color of the stool indicates the overall well-being of an individual.

When it comes to green stools, the color change could be due to the following:

  • Diet changes
  • Infections
  • Medications

Sometimes, green-colored stools could be due to bacterial, viral, or parasitic infections resulting in abdominal cramping, nausea, vomiting, and diarrhea.

What are the causes of green-colored stools?

The possible causes of green-colored stools include:

Diet

In most cases, green stools are due to including green foods in the diet, such as spinach, kale, and broccoli. Chlorophyll, a pigment present in leaves, which gives green color to the leaves, could be the reason for green stools. Small servings of green leafy vegetables may not change the color but taking larger amounts of green leafy vegetables may result in green stools.

Some artificial food coloring (green) may lead to green stools (such as green frosting on cakes).

The following are the foods and drinks that affect the stool color and turn them green:

  • Blueberries and some other purple and blue vegetables or fruits
  • Green fruits, such as avocados, green apples, and honeydew melon
  • Powdered green tea called matcha
  • Pistachios
  • Hemp seeds
  • Few herbs, such as basil, cilantro, and parsley

The color changes that happen with green-colored foods could be temporary and may not be harmful. If these changes persist for an extended period, contact your healthcare provider immediately.

Infections or any other underlying medical conditions

  • Gastrointestinal conditions
    • Affect the absorption of bile may result in green-colored stools.
    • In gastrointestinal conditions, such as Crohn’s disease, where the food passes very quickly through the intestines, the bile will not break down easily, resulting in green stools.
    • Celiac disease, caused by intolerance to gluten, causes various gastrointestinal problems, such as bloating, stomach pain, gas, and diarrhea with green stools.
    • Irritable bowel syndrome, overuse of laxatives, and ulcerative colitis cause the food to pass quickly through the intestine and may result in green stools.
  • Parasitic infections
    • Giardia, a parasite found in soil, water, and food contaminated with an infected person's feces, causes diarrhea, gas, stomach pain, nausea, vomiting, and dehydration, as well as foul-smelling, floating, and green stools.
  • Bacterial infection
    • Salmonella or E coli infection can result in green stools. Three to four days after coming into contact with E coli, an individual may begin to exhibit the symptoms. 
    • In Salmonella infection, the symptoms appear within six hours to days after eating the contaminated food or drink. Symptoms may include stomach cramps, diarrhea, and vomiting.
  • Viral infection
    • Norovirus infection easily spreads from the feces or vomit of an infected person to a healthy person. An infected person may contaminate foods, drinks, or surfaces that they touch.
    • Norovirus results in severe stomach upset, which is problematic but is rarely dangerous. This viral infection exhibits various symptoms along with green stools, such as diarrhea, vomiting, fever, body aches, and dehydration.

Medications

Antibiotics and, in rare cases, iron supplements can cause green stools. Antibiotics, which are used to kill harmful bacteria, can sometimes harm healthy bacteria. The green color of the stools is caused by the destruction of bacteria.

Iron supplements that treat anemia have a few side effects, such as nausea, vomiting, constipation, and dark or green stools.

QUESTION

Pancreatitis is inflammation of an organ in the abdomen called the pancreas. See Answer

What are the common symptoms of green stools?

The common symptoms of green-colored stools include:

How to treat green-colored stools

Typically, green stools may turn to a normal color once the underlying condition is treated after dietary changes are made, or once you stop taking the affecting medications. However, if the green color persists for extended periods, consult your doctor for further options.

Table 1. Other possible stool colors
Color of the stools Causes What does it indicate?
Light or pale or clay stools Due to a few medicines, such as bismuth subsalicylate and antidiarrheal drugs Bile duct damage
Yellow, oily, and foul-smelling stools Gluten-containing foods, such as bread and cereal Malabsorption disorders, such as celiac disease
Black stools Iron supplements and foods, such as licorice Sometimes could be due to upper gastrointestinal bleeding
Bright red stools Foods, such as beets, cranberries, tomatoes, and red gelatin Sometimes signs of bleeding in the lower intestinal tract

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Medically Reviewed on 11/4/2022
References
Image Source: iStock image

Why Is Your Poop Green? https://health.clevelandclinic.org/green-poop/

Stool color: When to worry. https://www.mayoclinic.org/stool-color/expert-answers/faq-20058080