I am taking a zpack and on day 3, i have an upset stomach and some diarreha, can i take pepto bismol (bismuth subsalicylate)?

Yes!: There are no known interactions between azithromycin (Z-pak) and Pepto Bismol (bismuth subsalicylate). To reduce upset stomach and diarrhea, take the z-pak with food, like a large meal such as dinner. You can also take Immodium AD to minimize diarrhea. After you finish the antibiotics, your upset stomach and diarrhea should go away in a few days. If not, see your doctor.