Bleeding in the stool (hematochezia) can be caused by internal or external hemorrhoids, anal fissure, colon polyps, diverticulitis, Crohn's disease, gastric ulcer, and of course, cancer. He should see his doctor for an examination to try to determine where the bleeding is coming from. Bright red blood is most likely to come from the lower end of the digestive tract and be from hemorrhoids (internal or external). Darker, tarry blood is more likely to come from higher in the system (gastric ulcer). Until he sees his doctor, he can try to keep his stool soft with fiber from fruits, vegetables, whole grains, and lots of water. You may try adding a fiber supplement such as Metamucil, Benefiber, or others. Soft stool will make passing the feces easier and less irritating.