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Dr. Andrew Rynne
Dr. Andrew Rynne

Family Physician

Exp 50 years

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What causes diarrhea and black stool?

Answered by
Dr. Enrique Molina

Internal Medicine Specialist

Practicing since :2004

Answered : 364 Questions

Posted on Mon, 10 Nov 2014 in Infections
Question: I have had extremely watery diarheaa for the past 3 days. It has turned into a black tar appearance yesterday. I have been taking Pepto Bismol, but read on the bottle not to take if had black stool. can you tell me why. What can I do to get some relief until I can get to my doctor tomorrow?
Answered by Dr. Enrique Molina 31 minutes later
Brief Answer:
possible bleeding

Detailed Answer:
black tarry stool is always a red flag for intestinal bleeding, most commonly coming from the stomach, small bowel, but could also represent bleeding from the colon.
The confusing part is that pepto bismol can turn stools dark near black without causing bleeding, which then confuses us physicians in order to determine if you are indeed bleeding or its just the medication side effect. You would need to get a blood test to check your hemoglobin and see if it is low, then it would be concerning for bleeding. Stool can be tested for microscopic blood, but this test is not 100%.
In my experience, when bleeding occurs, the stools are black tarrry, fould smelling. Pepto bismol cause stool to become near black, but these are usually solid stools, no change in smell.
If you are feeling weak, you should go to the hospital immediately to get checked out. Avoid pain medications (such as ibuprofen, naproxen, etc) as this can precipitate a bleed as well.
For the diarrhea, you should take imodium as needed, but i advise you to get seen as soon as possible by a physician.
Above answer was peer-reviewed by : Dr. Chakravarthy Mazumdar

The User accepted the expert's answer

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