Blood in your stool may look black and tarry or bright red, and you may notice it either on the toilet paper or in your feces. Noticing blood in your stool may cause you to feel alarmed, but this symptom does not always indicate a serious medical condition, although if it worsens or persists you may need medical evaluation. According to the Mayo Clinic and the National Library of Medicine, blood in your stool may be a symptom of digestive problems or injury to your rectum.
Hemorrhoids are growths on or around the opening of your rectum, and they may bleed as you pass a bowel movement, resulting in bright red blood in your stool.
An anal fissure is a crack or tear in the skin and membranes of your anus, and can cause you to bleed into your stool.
If the blood in your stool is dark or tarry, it may be the result of an ulcer in your stomach, especially if you also have symptoms including stomach pain and indigestion.
Inflammatory disorders of your bowel, such as Irritable Bowel Syndrome (IBS) and Crohn's disease may cause red blood in your stool.
Polyps are abnormal growths in your colon, and these growths may become irritated and bleed as your stool passes through.
Infections in your digestive system may cause you to have blood in your stool, and these infections can be caused by parasites, bacteria and viruses.