Tag: Melena

Fatalities have occurred, although rarely, due to severe reactions to sulfonamides like acetazolamide, including aplastic anemia and other blood dyscrasias [1.4.1]. So, does acetazolamide cause bleeding? While not a common side effect, it can occur through serious, indirect mechanisms [1.2.1, 1.5.1].

Many people are alarmed to see black stool, but the cause is often a harmless side effect of medication. Determining what medication causes black stools is crucial for understanding whether the discoloration is a benign chemical reaction or a sign of more serious gastrointestinal bleeding.

While roughly 25% of patients on metformin experience some form of gastrointestinal upset, true black, tarry stool (known as melena) is rarely a direct side effect of the medication itself and requires a careful look at other causes. The question, **why is my poop black on metformin?** points toward several potential factors, both harmless and serious, that need to be evaluated.