drugs can change stool color
Many patients don't realize their drugs can change stool color.
Black stools are common with iron supplements, charcoal, or bismuth (Pepto-Bismol, Kaopectate, etc).
Red or orange stools can be seen with phenazopyridine (Pyridium), rifabutin, rifampin, or antacids with aluminum. Omnicef (cefdinir) can interact with iron in baby formulas to produce reddish stools.