What Causes Dark Green Colored Stool?

Posted on Tue, 4 Jul 2017

Medically reviewed by Ask A Doctor - 24x7 Medical Review Team

Tue, 4 Jul 2017 Answered on

Tue, 1 Aug 2017 Last reviewed on

Question : Hello. I am a 68 year old XXXXXXX woman and I have had something come up in the last two days that I am wondering about. My stool is dark green, the color of spirulina. I don't take spirulina except in two or three swallows of Odwalla Superfood Juice in the morning, but I have been doing that for years and never had green stool. So I asked myself, "OK what's new in my diet that could have caused this?" There are a couple of items that are new, but other than the obvious dietary cause, I'm wondering where this color comes from. I feel fine, my stool feels normal, and appears normal, except for the color. And this has been going on for about 2 to 2-1/2 days now, several times a day. So is this liver bile that is causing this color? I am starting to experiment with eliminating the new things in my diet to see if that is the cause, but wanted to ask about this anyway since it's so unusual.

Answered by Dr. Dr. Michelle Gibson (1 hour later)

Brief Answer:
increase in stool frequency or diet related

Detailed Answer:
HI, thanks for using healthcare magic

Green stool can be due to an increase in stool frequency or due to diet.

Normally as stool passes through the colon, the bile that is present in the stool undergoes changes that causes the color change from green to brown.
If the frequency of bowel movements increase then the bile does not have the time to undergo these changes and the stool appears green.

If there is no increase in stool frequency then the green color is due to some component of the diet- green coloring/dyed foods, green leafy vegetables. In some cases the use of foods with purple/blue or black dyes can also cause the green color to be seen.

In most persons, the green stool resolves on its own

I hope this helps, feel free to ask any other questions

Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar

Follow up: Dr. Dr. Michelle Gibson (3 hours later)

OK, thank you. Could be due to both diet and frequency. It seems normal otherwise, including the smell, so hopefully it will resolve on its own and I won't have to do anything more about it. Thank you so much, doctor, for your help. XXXXXXX Storm
YYYY@YYYY

Answered by Dr. Dr. Michelle Gibson (24 minutes later)

Brief Answer:
no problem

Detailed Answer:
No problem

If there are any other concerns, can let me know

Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar

Follow up: Dr. Dr. Michelle Gibson (20 hours later)

As of last evening, 7/4/17, the problem had resolved itself and my stool is now back to its normal color. Huge relief. Thank you so much for your help. XXXXXXX Storm
YYYY@YYYY

Answered by Dr. Dr. Michelle Gibson (1 hour later)

Brief Answer:
yeahhh

Detailed Answer:
That's great.

That is what normally happens, glad that everything is okay now

Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar