Re: black and tarry stools + guinness

I have found that drinking guinness causes me to have these foul things. Is this a universal effect of guinness or a possible indicator of something wrong with my insides?

[boron]

Black tarry stool appeared soon after you tried Guiness for the first time, or it happened after a long Guiness history? :) Guiness may cause black stol, not sure if also tarry stool.

Black stool may also come from:
- bleeding from the stomach, esophagus, mouth, nose, throat, lungs (if swallowed). Bleeding from the stomach may be due to gastritis, ulcer (from H.pylori or drugs like aspirin, ibuprofen), cancer. The bleeding from below the stomach (intestine) would be red.
- licorice
- iron supplements
- Pepto-Bismol

So, the question is: is it blood in your stool or not. Answer can be get easily with FOBT (fecal occult blood test). If this will be positive, further investigation (uper endoscopy) will be probably needed.