Gas, bloating, diarrhea, and even incontinence are all unfortunately related to taking alli, which works by blocking fat digestion in the intestines. I can't really comment specifically on the color of your stool - any amount of blood in the stool is not normal and deserves medical attention (I can't know online whether this is or is not the case in your situation). Check out this article from a couple of years ago which provides a nice discussion of the topic and coins the phrase "Alli-Oops!" http://tinyurl.com/2ujs92 Take care.
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