Answers by TheMediTary.Com - Last updated: 14-Jul-2023
Dark colored / black stools are a common side effect and can last for several days after you stop taking Pepto-Bismol. This is not a serious side effect.
Give it a few more days and it should disappear.
Dark colored bowel motions can also be a sign of gastrointestinal bleeding so if it continues or you are concerned please see your Doctor.
See: https://www.drugs.com/mtm/pepto-bismol.html