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What are Some Causes of Green Stool?

J. Beam
J. Beam

While unpleasant a topic of conversation if ever there were one, the color of stool is a common concern for many people, especially mothers of infants and young children. The color and consistency of a bowel movement can be dependent on a number of factors. While red and black stool may be cause for alarm, green stool rarely is.

Green stool is not usually considered abnormal. Green stool may most likely be caused by dietary intake and is closely related to the amount of bile in the stool. Bile is a yellowish green fluid found throughout the digestive tract that digests fat. Under a variety of circumstances related to the body’s gastrointestinal health at the time, bile can cause stool to become different colors or at least varying shades of the same color. Green is not uncommon and may be the result of too much or too little bile or food moving through the intestines too fast.

Eating spinach may cause green stool.
Eating spinach may cause green stool.

Diet can also effect stool color. Green vegetables, such as spinach and broccoli can cause green stool, and foods containing green food coloring can yield the same result. Just as often though, other food colors can have the same impact. Purple drinks are a particular culprit, especially in young children. Some dietary supplements, especially iron, can also cause green stool.

Constipation can cause green stool.
Constipation can cause green stool.

Another factor that could contribute to green stool is mucus. Mucus is present in the intestines and can cause stool to change color as it can consistency. Unless there is an excessive amount of mucus or a persistent change from normal bowel movement, it is likely nothing to be concerned with.

If you have recently changed your diet, have consumed a large quantity of sugary foods, or have had constipation, your stool may appear green a time or two before returning to normal. If you have green stool with other symptoms and cannot think of a reason why your bowel movements may have changed, call your doctor. While green stool is not considered abnormal, serious or chronic changes in bowel movement may indicate a cause for concern. Stool that is red or black may contain blood and should be discussed with a doctor. Many abdominal and digestive disorders and diseases are diagnosed with a change in bowel habits.

Discussion Comments


I've had green bowel movements for about two weeks now. I have not eaten any green veggies, no colored drinks, no vitamins. No new meds. It also looks like it has sparkles in it. I know it sounds weird but it's never happened before.


I believe that all the grass my dog eats turns his stools green. He grazes on it sometimes, and if he doesn't throw it up, it comes out in his stool.

Sometimes, it hasn't been fully digested, and I can see the individual blades. Other times, the whole stool just looks green.

I've heard that the chlorophyll in grass can turn a dog's stool green. I suppose there's no harm in this.


I eat spinach every day at lunch, so it is no rare thing for me to have a green colored stool. Spinach is just so good for you, and by eating it every day, I am ensuring that I get plenty of vitamins.

The stools aren't a bold, startling green, though. There is more of a mild green tint to them.


@giddion – I used to wonder the same thing. A loose green stool is rather alarming.

I learned that it has to do with how quickly the stool passes through your bowels. Stools start out colored green by bile, and when they move slowly, they gradually turn brown. However, in the case of diarrhea, they move too quickly to change colors, so they come out green.

So, green diarrhea doesn't necessarily mean you have a disease. If it just happens one or two times and over the counter medicine stops it, you will probably have nothing to worry about.


What can cause green stool diarrhea? Many of the things mentioned in this article are referring to stools of normal consistency. Is there an illness that makes diarrhea green sometimes?


Grape kool-aid causes green stools in kids. How funny is that?


I am glad to read this article. My daughter just had a bright green/bluish bowel movement and I just thought at first it was hilarious. Later on I thought about it and was afraid it may indicate a real problem. I remembered back to my older son who also had this same problem, but the cause was too many twizzlers! Thanks for this article!


My son is three years old, and almost always has green bowel movements. I am really trying to figure this one out. It doesn't matter what color the food or drink is that he has ingested. All three of my children take a multi-vitamin daily. This does not happen to my other two children. I am going to try and take that out of his diet and see if that helps. If anyone has any other suggestions, I would love to hear them. Thanks! --jdk


A messy uni night out caused quite a sore hangover the next morning. I had green stool for the first time and didn't realize what it was. Quite a scary experience, actually!

After researching this informative site, I've come to the conclusion it was the numerous 'cheeky vimtos' that I consumed last night. Not sure I'll be able to handle any more of those again! Thanks for the information, though.


I eat a lot of green food, but this had never happened to me before today. The placebo in my birth control packet is an iron supplement. I wonder if that's the cause.


My daughter ate a donut this morning that was covered in blue sprinkles. This evening she had a crayola crayon green bowel movement. After a small freak-out I realized it was the food coloring from the sprinkles. Mystery solved (and no more blue sprinkled donuts!)


Try a gummy type of multivitamin, either One a Day or vitafusion's MultiVites. Neither have potassium or soy.


This article has just solved a mystery for me ! My three year old son has just had two *really* green bowel movements. it looked like he must have consumed green food dye or a crayon. I have just realized he had been drinking blue coloured soft drink and it was coming out green! What a relief. And no, he won't be allowed any more blue drinks!

Great article. This is one of the good things about the internet! Catherine, Melbourne Aus.


I have also had this happen to me many times. I have edema in my right leg and I should take potassium pills but it seems to increase the swelling if I do that. Most multivitimans have potassium so I stopped taking them. I have not found a multivitiman yet that I can take.


This has happened to me when I tried to take a multivitamin. I'm not sure if it's the soy commonly used as a filler in most multivitamins, or the iron, or a combination, but they always make my stomach hurt and my stool turn green. The situation usually only gets worse from there, so I've stopped taking them altogether.

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    • Eating spinach may cause green stool.
      By: Alessio Cola
      Eating spinach may cause green stool.
    • Constipation can cause green stool.
      By: Ljupco Smokovski
      Constipation can cause green stool.
    • A change in bowel habits may indicate the presence of a digestive disorder.
      By: Halfpoint
      A change in bowel habits may indicate the presence of a digestive disorder.
    • Abnormal, serious or chronic changes in bowel movement may indicate a cause for concern.
      By: graphicgeoff
      Abnormal, serious or chronic changes in bowel movement may indicate a cause for concern.
    • Consuming a large quantity of sugary foods may turn stool green briefly.
      By: robcartorres
      Consuming a large quantity of sugary foods may turn stool green briefly.