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

Varying shades of brown is accepted as the normal stool color but sometimes it may be other colors. Most of these other hues are considered as abnormal. One of these abnormal colors ia green tinge to overtly green color of the bowel movement. It has to be investigated as this can be a sign of various diseases. The condition is even more serious if there is diarrhea that is green.

Most of the time green bowel movement and green diarrhea are thought to be due to bile. This is the substance that is produced by the liver and stored in the gallbladder. Bile is naturally a greenish color and released into the small intestine during the digestion of food. However, bile is reabsorbed and also processed by colonic bacteria which yields a yellow to brown color that gives stool its natural color.

Causes of a Green Bowel Movement

Green bowel movement that is of normal consistency and not overly frequent like in diarrhea is mainly due to strong dyes or colorants staining the stool a green color. This may arise with certain foods, beverages, medication and supplements. Sometimes these substances are not green in color but with digestion and interaction with other substances in the bowel, these substances may make the stool appear green in color.


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 the first few days after birth. This is normal. It may also occur later in infancy due to breastfeeding. Some baby formulas may also cause a green color f infant stool. Children on a clear-liquid “starvation diet” during illness may have green watery stools since bile is the only substance that is passing through the gut and out of the bowels.

Medications and Supplements

Certain medication and supplements, that are taken orally, may cause green bowel movement for several different reasons. The following drugs and supplements are more likely to cause green bowel movement:

  • Iron supplements
  • Laxatives – due to shortened bowel transit time (movement through the gut).
  • Algae
  • Chlorophyll
  • Children syrups often contain sweeteners fructose or sorbitol that both can speed up peristalsis what may result in green bowel movements.
  • 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 movement through the bowels.

Causes of Green Diarrhea

Sometimes an abnormally green color of the stool is also associated with diarrhea. Therefore the diarrheal stool apears green in color. In these cases the greenish hue may be due to the unprocessed bile or due to other causes that can taint the stool green while causing diarrhea simultaneously. For example, a green colored alcoholic beverage like sambuca can cause diarrhea when consumed in excess while tainting the stool with its strong green color.

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) is where there is reverse flow of stomach acid and in some instances there may be associated diarrhea which can be significantly stained with bile.
  • Thyrotoxicosis – elevated levels of hormone thyroxine in the blood, usually due to autoimmune thyroid disorder (Grave’s disease)
  • Impaired gut innervation, common in diabetes when a condition known as diabetic neuropathy occurs. This alters bowel motility.

Impaired Bile Re-absorption in the Small Intestine

As bile passed down the gut, it is processed by the digestive system. Bile salts that are in the bile and largely responsible for its green color is reabsorbed to some extent. It is then processed again by the body. Bile salts are absorbed into blood mainly from last part of small intestine (terminal ileum). Causes of impaired bile re-absorption includes:

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

Some of these bile salts are then secreted again in to the bowel through the bile or processed by the kidney and expelled with urine.

What to Do, If You Have Green Bowel Movements?

Green bowel movements due to ingested food or medication/supplement are normal, and may not require any medical intervention. The stool will return toa  normal color once the causative substance is flushed out of the digestive tract. However, medication and supplements should not be stopped until a doctor or pharmacist advises so. Green bowel movement is not always serious in these cases but should nevertheless be investigated if it is persistent.

In all other cases, especially if symptoms like fever, diarrhea, constipation, weight loss, or general malaise are present, then it needs to be investigated by a medical professional. Sometimes this greenish stool can be due to a serious underlying disorder. It is important to bear in mind that greenish bowel movement is just a symptom some underlying condition or temporary disturbance. A stool sample may have to be collected and sent to a laboratory for analysis.

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About Jan Modric (249 Articles)
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  • marcy

    I have had olive-green diarrhea for 3-4 days now. I have discomfort in my lower abdomen too. Can a “behind” (but vaginal) sexual position cause this? I don’t know if the pain is from the intercourse or the diarrhea, but it does hurt. It hurts when I go to the bathroom AND when I stand. Does any of this make sense? Can fruit punch juice cause the olive-green color? If so, could the pain just be from a different sexual position?

  • Jan Modric


    fruit punch juice is a possible cause; in this case, and if you did not have a lot of other fruits or alcohol, it should go away soon.

    In fructose malabsorpotion, fruits themselves can cause diarrhea.

  • Pingback: Black Bowel Movement & Black Diarrhea - Causes | Current Health Articles 2009()

  • roxy

    I have add bowel movements from 2 day japanese diet. what is in them?

  • Jan Modric


    it can be from green vegetables, spices, stimulated peristalsis or food poisoning.

    If you have no loose stools or fever, you can just wait a couple of days and your stool should get its usual color.

  • Charlie

    I have had green bowel movements for 2 weeks off and on. I notice they come after yoga classes. Can the twists we do have something to do with this? I am a vegan, but do not eat excessive green food. I feel totally fine otherwise.

    • Jan Modric


      bowel movements are green due to green vegetables, certain food additives, or bile. Yoga exercises could stimulate the passage of (green) food and/or (originally green) bile through your bowel, and then either the food or bile would color the stool green. If stools are loose and contain undigested food, you are losing nutrients this way. If stools are of usual consistence, the green color is probably from the green food.

  • alex

    Im 17 year old female. Doctor diognosed me as lactose intolerant about a month ago. I had blood test testing for celiac and chrones but turned out negative and everything else was fine besides my iron being a bit low and my stool test testing for parasites which also came back negative but it was taken when i wasnt feeling as bad at all. Ive cut out all lactose foods yet im still having to go toilet maybe twice each morning with dark green diarrhea with white mucus and for the next 2 hours im still feeling a bit sick and malaise. ive also had some weight loss, always seem to urinate and i get full easily but end up hungry again within the nest 10 minutes. Wondering if it is parasites, i do sometimes get small bumps all over my hands if that helps also. What is wrong with me 🙁

    • Jan Modric


      Stool tests for parasites are often false negative. They are more likely positive when symptoms worsen, and still sometimes repeated tests are necessary. One possible cause of green diarrhea is Giardia (an uni-cellular parasite). I recommend you to visit a gastroenterologist.

  • Annelise

    I have had dark green bowel movements for about 5 days now and I don’t know whats causing it. I don’t have and discomfort or diarrhea. I haven’t been eating a lot of green foods either. Though I was sick with a stomach virus for about a week that cause frequent diarrhea, after the diarrhea went away my bowel movements got real mucousy and then became normal for about a day or so and now they have been dark green. The only thing that I can think of that I’ve been eating a lot is Triscuits…could anything in those cause this? Or should I see a doctor?

    • janmodric


      Symptoms from viral diarhea and bacterial food poisoning usually resolve within a week, but symptoms from parasites can persist for weeks or months. So, if green bowel movements will persist for few next days, you can consider to have a stool test for parasites. Green bm as such is not dangerous – it reflects fast transit of food through the bowel; Triscuits are high in fiber and could stimulate the bowel.

  • ani

    I’ve been feeling kind of ‘off’. Really weak and tired (not anemic), frequent urination and bms (normally I can only bm 2-3 times a week), abdominal pain sometimes and bright green bms for 4 days now. But there’s no fever or pain. I’ve also noticed that I’ve lost 5lbs in 2 days. There is no way I’m pregnant… What’s wrong w/me?

    • Jan Modric


      one possible cause is food poisoning either with bacteria or parasites – they often appear without fever. Lost weight may be from dehydration, so you should drink enough water and also try to eat regularly if possible. Bacterial food poisoning usually heals by itself in few days, but intestinal parasites can last for weeks. So, if ymptoms won’t go away in the next days, a doctor can order appropriate stool tests. Frequent urination can be due to pressure of the distended rectum upon the bladder or due to urinary infection.

  • Ashley

    My husband has had green stools for about 5 days and neither of us can figure out why. I make his work lunches and we eat dinner together every night. Once in a while we eat out. I know he doesn’t eat a lot of green leafy veggies or anything with food dye (usually). In his lunches I pack an apple, a yogurt, a wrap (tortilla, lunch meat, and cheese), a power-aide, and a Mt. Dew Throwback, among other random things, but I give him those every time. He also works as a Lot Loader for Home Depot so he’s alway’s going from inside to outside and back again and he lifts the heavy bags of concrete and mulch, etc…. We live in Southern Texas and it’s getting pretty hot out. Could anything I mentioned above have anything to do with he stool being green? I don’t know the consistency or exact color, but I do know he’s worried about it. Oh, one other thing, the other night after dinner, he complained about his abdomen hurting and feeling kinda “blah”. Please help us figure out whether he should see a doctor or just wait it out. Thanks.

    • Jan Modric


      green stools often appear in infection with an intestinal parasite giardia or overgrowth of Clostridium difficile bacteria. Stool tests for both exist.

      Other than that, practically any bowel disorder that stimulates peristalsis could result in green stool (diarrhea). From these, bacterial food poisoning usually heals on its own within a week. Infection by parasites often has to be treated though.

  • sexyand34

    I have been having a bowel problem. For about a month I have been having green bowel. I have not been eating anything green or even change my eating habits. I have pain up to the moment I have a movement. I dont go but really about 4 times a month. Any ideas?

    • Jan Modric


      Constipation and green bowel movements could be from intestinal parasite, like giardia, to mention one likely cause.

  • Tessa

    Im 14 and I have been having green stools for about a week. Its really uncomfortable and its embarrassing at school. I dont know what causes this. I dont really eat any green foods. I make brownies every week and eat some of the batter (it has raw eggs in it) could that be the reason? This is the first week in a couple months though that I havent.

    • Jan Modric


      if stools are solid, like before, it can be some food, including brownies. Artificially colored foods, like icecream, certain drinks, also vitamin or iron supplements can cause green stool.

      If the stools are loose (diarrhea), it can be from food poisoning, or intestinlal parasites, like giardia.

      You can try to stop eating brownies for some days and see if it helps. If not, and if you have diarrhea, ask your parents to arrange an appointment with a doctor for you, since you might need to have a stool test.

  • CollegeStudent

    I’ve been having similar problems that others listed. Diarrhea for about a week, and it has become progressively lighter in color (from light brown almost to a grey/green color) and progressively less solid and more liquid. During this week my abdomen has felt as if it’s bubbling and there have been intermittent pains (which do not last long but cause me to double over). I’ve just felt weak and fatigued this whole week and I’m starting to get very worried. The only difference in my lifestyle is that I visited Las Vegas, NV a few weeks ago and I just turned 21 so I had been drinking a lot of alcohol around that time. Help!!

    • Jan Modric


      in diarrhea after travel, intestinal parasites, like Giardia, have to be considered. Diagnosis is with a stool test for “ova and parasites”. Intesinal parasites sometimes heal on their own, but often prescribed antiparasitic medications are necessary.

      Other causes mentioned in the article are also possible.

  • lisa

    My husband has had green diarrhea for 3 full days, no stool just green water. I gave him imoduim ad to stop the diarrhea and now he cant go at all, he is bloated and has stomach pains. What is going on?? He does not eat veggies, and is feeling weak. Drinking gator-aid and very little food. HELP

    • Jan Modric


      the first thought in diarrhea lasting for few days is food poisoning with bacteria or intestinal parasites. There could also be overgrowth of Clostridium difficile bacteria in the colon, which may be dangerous. He should stop taking imodium, so the bowel can clear up. He should drink enough fluid. I recommend he visits a doctor who can perform appropriate investigations.

  • Kathy

    I have had diarrhea for over a week and have had stool tests. My doctor thinks it could be rhinovirus but l wont know until next week. I am now having bright green watery diarrhea and have not really ate much for 7 days, also l have pain when l do eat anything. Can you please help im feeling so very weak.

    • Jan Modric


      it is OK to eat when you have diarrhea. Also, it is important to drink enough water. You could be weak from not eating and dehydration.

      Diarrhea from a viral infection rarely lasts for more than a week, so, if not already done, you can also ask about stool test for parasites and for Clostridium difficile toxin.

  • lem

    My 4 year old son has been having very frequent and very soft bowel movements for about 8 months now. Often times the BMs are a bright green color. Recently, he has started having bleeding and itchiness at his rectum and I have consulted with his doctor who said that he just needs to have his diet “bulked up” so that the food will stay in his system longer. I asked him whether there was a possibility of lactose intolerance or possibly a candida overgrowth but he dismissed those ideas. My son eats a well balanced diet and otherwise does not appear to have any digestive issues. He is highly energetic as well. . . but these constant watery bowels movements have me concerned and are causing him to have a very chapped rectum. Thoughts?

    • Jan Modric


      intestinal parasites or a chronic bacterial infection (but not likely candida) can cause green stools, itchy rectum and rectal bleeding. His symptoms do not sound just diet related to me. A gastroenterologist can order appropriate stool tests, or other investigations if needed.

  • Chloe09

    I have had lower stomach pain for at least a month now and every morning i wake up feeling a lot of pressure in my stomach and i have to use the bathroom usually once but sometimes i go twice within the first hour i am awake. I always have light green colored poop. What does that mean she i go to the doctor

    • Jan Modric


      except certain foods (spinach, certain drinks, etc) and iron supplements, they are intestinal parasites that can cause green stool. A doctor can order a stool test for parasites.

  • ThorneBlackburn

    20 yr female here, experiencing pale green diarrhea with serious abdominal cramps. I’ve been eating more salad than usual over the past few days, and sandwiches with Mayo made with extra virgin olive oil. Could either of these be the reason?

    • Jan Modric


      if green stool will persist for more than two days after stopping eating green colored foods, I recommend you to visit a gastroenterologist. Salad and olive oil as such should not cause “serious abdominal cramps”.

  • bex

    i have been having bad diarrhoea for a few days now and the past few i have also had a very high fever. yesterday and today my diarrhoea has become more watery and is changing between an olive green colour and quite a bright yellow. i dont eat any coloured foods so it cannot be from that. I have had a look at a few various sites but cannot seem to find an answer, the soonest my GP can see me is monday

    • Jan Modric


      sudden diarrhea is often due to bacterial food poisoning, which usually heals on its own within a week. High fever is not common in food poisoning, though. In general, diarrhea can occur during various systemic infections, like flu. In this case, other symptoms, like runny nose or muscle pains, are common. If high fever persist, I recommend you to visit a doctor as soon as possible. You could have an overgrowth of Clostridium-difficile bacteria overgrowth in the colon, which is potentially a life-threatening condition.

  • Moomoo

    To Alex
    I’m also a 17 year old female with all of your listed symptoms besides the hand bumps. Negative blood work does not mean you don’t have celiac disease. I don’t test positive for any of the markers however I do test positive for celiac gene. It is also necessary to have a colonoscopy with biopsy of the digestive tract to determine if your villa are blunted. Celiac disease often goes undiagnosed and left untreated will cause cancer. The good news is that the treatment is a strict gluten free diet no harsh medicines required. I just wanted to make sure you had the appropriate tests taken. My father died of colon cancer at the age of thirty probably from undiagnosed celiac. Just by not eating gluten he probably would be around for me. Hope you figure out what is wrong with you.

    • 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

  • Billyyy

    I’ve been having stomach pains on and of in my lower stomach for about a few days and pooping green stool but again its on and of like i’ll be ok one day and then the next my stomach will start acting up . I think its because of my diet i’ve been eating alot of pasta and heavy foods and drinking lots of soda . Any ideas on what the problem is and what should I do to fix it ?

    • Jan Modric


      stop drinking soda and excess of any food and see what happens in few days.

  • Chinah

    Okay my diarrhea is like an olive-green color and its been going on all through the night and in sveral caes the foods were’nt digested all the way and also after many visits to the restroom, about every 20 mins or so, its started to burn to wipe my anal area.. also Ive vomitted about 1 time, so what caould be the cause of this?

    • Jan Modric


      sudden diarrhea is often caused by food poisoning. Bacterial food poisoning usually heals on its own in few days without any medications. If it lasts for more than a week, you should see a doctor. Be sure to drink enough water. You can eat what you feel comfortable with.

  • concerned dad

    my four year old son eats Kosher with his dumb-ash mom….. and when he is with me, he occasionally has green poop (real green and almost bright). I give him turkey cold cuts with american cheese. Can this be the cause? thanks

    • Jan Modric

      concerned dad,

      if he has no diarrhea (loose stools) or other symptoms, and if stool is green only occasionally (his mother should know) and he appears healthy and feels fine, then a bright green stool is probably from some food additive either in the turkey or cheese or other commercial food.

  • 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.

  • 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.