Does pesto bismol turn tour stools black?

Pepto-Bismol can indeed cause your stools to turn a dark color, typically a dark brown or black. This change is due to the active ingredient, bismuth subsalicylate, which can react with sulfur in the digestive tract to form bismuth sulfide. While this is generally harmless, if you experience black stools without taking Pepto-Bismol or if you have other concerning symptoms, it's best to consult a healthcare professional.