Gastrointestinal pain and bleeding?

Common, serious...: The most likely cause of GI pain and GI bleeding are medications that irritate stomach lining causing gastritis, ulcer disease, severe reflux, esophagitis. Most common are aspirin, meds related (nsaid's--ibuprofen, naproxen)--anti-inflammatory drugs. If note reddish stool, or stools turns dark or black, or GI pain occurs, call your physician, who will tell you if you should come to office or er.