Green Bowel Movement and Green Diarrhea – What Are the Causes?

Causes of a Green Bowel Movement


Green bowel movement may be normal for a person that ingests a lot of:

  • Green leafy vegetables like broccoli, lettuce, spinach, cabbage
  • Black licorice
  • Baby formula – vegetable mashes
  • Artificial colors, commonly added to ice creams, soda, fruit juices, or other drinks, morning cereals, milk products, sweets, etc.
  • Iron-rich foods like enriched breakfast cereals, red meat, spinach, beans, etc.

Dark green color may persist for up to five days after ingesting above mentioned foods. Supplements or artificial colors may give bright green color to the stool.

In infants, stool is green in first days after delivery, and later due to breastfeeding. Some baby formulas can also give green color to infant stool.

Children on clear-liquid “starvation diet” during illness may have green watery stools.

Medications and Supplements

Medications and supplements, giving stool green color, if taken by mouth:

  • Iron supplements
  • Laxatives – due to shortened bowel transit time
  • Algae
  • Chlorophyll
  • Children syrups often contain sweeteners fructose or sorbitol that both can speed up peristalsis what may result in green bowel movement
  • Vitamins /mineral supplements, or eventually any other medication or supplement taken by mouth, if it is artificially colored, or if it contains fructose or sorbitol, that may speed up peristalsis

Causes of Green Diarrhea

Decreased Bowel Transit Time

Green bile, after excretion from the liver into duodenum, slowly changes to yellow, and then to brown color due to chemical changes performed by normal intestinal bacteria and enzymes. When the bowel content flows through the intestine fast, original bile color does not change, resulting in green or yellow stool. Causes of decreased bowel transit time include:

  • Diarrhea – loose bowel movements; there are several causes of loose bowel movements, including food poisoning (giardia and salmonella infection often result in green diarrhea), rotavirus infection, food allergies, lactose intolerance, fructose malabsorption, celiac disease, Crohn’s disease, ulcerative colitis, and so on.
  • GERD (Gastro-Esophageal Reflux Disease
  • Thyrotoxicosis – elevated levels of hormone thyroxine in the blood, usually due to autoimmune thyroid disorder (Grave’s disease)
  • Impaired gut innervation, common in diabetes

Impaired Bile Re-absorption in the Small Intestine

Bile salts are absorbed into blood mainly from last part of small intestine (terminal ileum). Causes of impaired bile re-absorption are:

  • Inflammation of the small intestine, mainly due to Crohn’s disease
  • Surgical removal of the terminal ileum

What to Do, If You Have Green Bowel Movements?

Green bowel movements due to ingested food or medication/supplement are normal, and do not require any action. In all other cases, especially if symptoms like fever, diarrhea, constipation, weight loss, or general malaise are present, you should visit a doctor, because a serious underlying disorder may be present.

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  • Natalie


    When I eat pasta, I make my own sauce. I fry up onions, mushrooms, garlic and sweet red peppers in olive oil (a lot of olive oil btw) and add canned tomato sauce. After about 30 minutes I get watery BMs. This only happens after I eat this meal.

  • Jan Modric


    you can remove ingredients one by one from the sauce to see which one affects you…

  • steve

    For three days I have had green/yellow diarrhea. I have been drinking lots to stop myself being dehydrated, and I’ve been eating simple meals such as beans on toast.
    I feel that I might have food poisoning from pasta I had a day before I got the diarrhea. A friend cooked a dish consisting of chorizo sausages, tomato, peppers and pasta.
    Though I had cinema popcorn on the same day.

  • Jan Modric


    bacterial food poisoning could result in a green/yellow diarrhea, which should stop on its own within a week without any treatment. Sausages/pasta sounds much more likely cause than popcorn to me. Doctors now advise a regular diet (what you feel comfortable with) during diarrhea. Water or a sport drink (with sodium and glucose) is good for rehydration in mild diarrhea. If diarrhea doesn’t stop in a week, I recommend you to visit a doctor and consider the possibility of a parasitic infection.

  • JimSamson

    I’m a 22 year old male who works 11 hour days and has a pretty bad diet. for the past 4 days I’ve had diarrhea with high fever(went away after 24 hours) but on the 4th day(today) I had slightly loose stool that was 100% pure emerald green. Is this a sign of something very serious? or is it just diet/food poisoning. I’m actually quite nervous it’s been 4 days the movements are much further apart just alot of cramps (feels like trapped gas) Should i be alamred by any of this or am i just getting over a case of food poisoning?

  • Jan Modric


    bacterial food poisoning usually heals on its own within a week. If not, intestinal parasites (like giardia) can be suspected – for this a stool test and appropriate treatment is recommended otherwise the infection may last for weeks or months. Another possibility would be Clostridium difficile (bacterium) overgrowth in the colon (a special stool test is needed for the diagnosis) – if your temperature rises again, I recommend you to visit a gastroenterologist right away.

  • Mommyb

    Ok-my little boy 12mo had a fever of 104.3 yesterday and did nothing but sleep and let me hold him. He drank well and ate 2 popice’s so he stayed well hydrated. He ate slightly less than normal, but not a really significant amount less. His only other symptoms are a clear runny nose and gas (and seems to strain when he toots). He hasn’t pooped in 3 days. The week leading up to this he had a BM everyday, most days 3 times. This I’d much more than normal for him-typically it’s about 3x a week. So I finally gave him a suppository and he cried when he went. It was pretty watery and bright green/yellow in color with two pieces in it that were the consistancy of really thick icing or toothpaste. I noticed the area surrounding is penis looked swollen. So I mashed on it a little, and it felt kind of full. He was already upset from popping so he was crying, so I couldn’t tell if this bothered him. However, to be honest, I haven’t seen enough men to know what’s “normal.” I don’t really examine my husband so I just don’t know. Thoughts?

  • Jan Modric


    if you suspect that the area around his penis is inflamed, please take him to the doctor as soon as possible. His condition could be caused by a certain viral infection, but I cannot determine this in more detail. Two thick pieces in his stool could be from the suppository, food, but I cannot exclude intestinal worms.

  • heather

    Hi Alex,
    Interesting all the blood works said negative to celiac disease, how did they test you for the celiac gene, did your doctor do it or did you request for it to be done as my daughters came out negative but she gets really bloated, you can see it like u are pregnant, she is much better at the moment she said she thinks it is the milk like chocolates etc, but the test for all this came negative. gastroscopy showed mild gastritis, did not have a colonoscopy done, all started in 2012 June and still comes on and off she is ok with glueten products but drinking or eating milk tends to irritate her stomach that is what she says but there are times she will have a couple of chocolates pieces and ok then she had about 5 pieces and it started to bloat is this common if you have IBS or celiac Thanks HG

  • Gia

    Green stool can also be caused by an overactive thyroid. It speeds up everything in the body and so the bile doesn’t get processed and the stool remains green vs turning brown. Other things you’d notice with a fast thyroid are weight loss, much more frequent defecation, like 4-5x a day, overall itching, faster heartbeat, swollen ankles and shaking…

    I know 1st hand cause i have Graves.

  • Nicole Woolard

    I have had loose bowels that are a blackish green and cramping in my stomach since Saturday. I do not feel bad other than that. As soon as I eat it goes right through me. Today makes day 5. Should I call the doctor?

  • Soul intentions

    So I just started having green bowel movements today .At least 5. very strange because I usually only go once maybe twice a day. The first time, it was solid, and the rest not so much. The last few came almost suddenly and could not be ignored. I haven’t eaten anything green nor a taken any suppliments . except for some olives 4 days ago. I’ve eaten way more olives than that before without the green “results” .I’ve gone since then and my bowels were not green , but normal. I feel I may be pregnant , but it’s very doubtful .I have some signs but not all . because PMS signs resemble early pregnancy signs extremely closely, it’s hard to tell and I don’t know what to think at this point. Work is slow and I can’t afford a Doctor at the moment. If there’s input or something I can be given , that would be great. Either in pregnant or something’s wrong with me because the whole green thing is very sudden and strange. The last time I went green I took one too many iron pills. That was years ago.