What Causes Green Diarrhea and What to Do About It

Don't panic if you have the occasional green stool (green poop). In most cases, there is a reasonable explanation for a green bowel movement that doesn't involve a health problem or condition. Having one formed green stool may not be a concern as long as the color of the next bowel movement goes back to a more typical color.

causes of green diarrhea
Verywell / Joshua Seong

Green diarrhea may be a concern, however, if it goes on for several days. When green diarrhea can't be explained by a food source or a virus that causes vomiting and diarrhea, it's best to consult a doctor.

Green diarrhea could still be within the range for what is considered to be a normal stool, even though it is loose. To explain the green stool, think back to the foods recently eaten or any vitamins or supplements taken over the last several days—even if those things are not actually green. Purple, black, or other dark colors in foods could also cause stools to turn green.

Medical Causes of Green Diarrhea

It's not common, but stool can also appear green for physical reasons and not from a food or supplement. In some cases, the green stool might be a sign of a medical condition.

Healthy stool tends to brown, with some variation in shade. However, bile that is secreted in the first part of the small intestine is actually green. As stool continues through the digestive tract and passes through the large intestine, it changes to become a darker brown.

If stool is still green by the time it is excreted from the body during a bowel movement, it could mean that it went through the large intestine too fast to be turned brown. This is often called "rapid transit" or "decreased colonic transit time." Rapid transit could cause stool to be green.

This is especially true if it is green diarrhea, rather than a fully-formed green stool. Food that is moving so quickly through the digestive system will not spend a long enough time in the large intestine for water to be absorbed and will result in a loose stool.

Green diarrhea should be checked out by a physician, especially if it is accompanied by other symptoms, or the green can in no way be explained by a food or supplement.

Food or Supplement Causes

There are several non-medical reasons that stool can appear to be green. If the green stool is also diarrhea, it could be tied in with eating unfamiliar foods or because of an illness.

If the green color could be connected to one of the reasons below, and the diarrhea goes away on its own in a day or two, the green diarrhea is probably not a cause for concern:

  • Eating green foods: The first and most obvious reason for a stool to be green is from eating green foods. Green leafy vegetables contain chlorophyll, which could be coloring the stool green. Green food coloring is also a common reason for stools to be green.
  • Eating purple foods: Foods with dark purple coloring, such as Kool-Aid, popsicles, and gelatin (Jell-O), can also result in greenish or green stools.
  • Iron-rich food or supplements: Iron supplements or even those foods that are rich in iron also have the potential to give stool a green tinge. If an iron supplement is causing too much digestive distress (such as bloating or constipation), talk to a doctor about switching supplements.

Holiday Sources of Green Diarrhea

Is it the week of a holiday or a special event? One of the biggest times to see green stools is during holidays when foods may be died green artificially, such as St. Patrick's Day, Easter, or Christmas.

Many people might not connect the green coloring to their stool, or may even forget that the holiday changed their normal eating patterns. Eating unfamiliar foods with new ingredients could cause looser stools, especially if there's a lot of fat content in the food.

A green stool might not appear for a day or two after eating green foods, and by then it is easy to forget what was eaten.

Green Stools in Infants and Children

In breast-fed infants, green stool is a normal occurrence, especially in the first days after delivery, and is no cause for alarm. In infants, stools will gradually change to become yellow and then brown, as the baby approaches the first birthday and more varied foods are added to the diet.

For formula-fed babies, green stool may continue for several months, likely due to the iron content of some formulas. Giving an infant or a child an iron supplement (as is commonly recommended by pediatricians) may also cause green stools.

In older children, the reason for a green stool could be food-related as described above, or even from non-food items. Eating or sucking on colored items, such as crayons or markers, might also put green coloring through the digestive tract and turn stools green.

Talk to a pediatrician about any concerns over a child's stools. If a child has swallowed or eaten a non-food object, call the American Association of Poison Control Centers at 1-800-222-1222.

When to Call a Doctor

If green diarrhea continues, or bowel habits have changed in other ways, contact a doctor to find out if there's a cause for concern. This is especially true if diarrhea goes on for days and is leading to dehydration or other complications. Call a doctor immediately if there is abdominal pain, nausea, or vomiting along with the green diarrhea.

A Word From Verywell

The occasional green stool is not usually a cause for alarm, especially if it goes away on its own or is from a pretty identifiable cause, like green foods. Thinking back on the last several days of foods eaten can usually provide a clue as to what's going on (keep in mind that it doesn't always have to be from green food: it could also be from blue, purple, or black).

Green diarrhea is another story, especially if it does not go away on its own and can't be traced to foods, supplements, or a viral illness. In that case, contact a doctor to be examined, especially if there are other symptoms.

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Article Sources
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