How long does it usually take for antibiotic side effects like nausea or diarrhea to start, and can pepto bismol (bismuth subsalicylate) be used to treat them?

Antibiotics+diarrhea: If a medication causes nausea, that usually happens right away, within an hour of the first dose. Diarrhea can start after a longer period of time - from several hours to several days. The illness being treated can also be the cause of the diarrhea. Sometimes antibiotic-associated diarrhea requires that we stop or change the antibiotic. if fever or painful diarrhea, please talk to your doctor.