Ulcerative Colitis

• Ulcerative colitis is an autoimmune disease involving inflammation of the rectum and large intestine. According to Mayoclinic.com, blood in the stool is a serious symptom associated with ulcerative colitis that requires prompt medical attention.
  
  

Food Poisoning

• Food poisoning occurs when foods tainted with high levels of bacteria are ingested. According to wrongdiagnosis.com, food poisoning caused by E. Coli, salmonella and shigella bacteria can cause bloody diarrhea.
  
  

Crohn's Disease

• Crohn's disease is a condition that causes inflammation in the digestive tract. Inflammation can occur anywhere from the mouth to the anus, though it's usually confined to the intestines. Bloody diarrhea is one possible symptom of Crohn's disease.
  
  

Diverticulitis

• Diverticulitis is a condition caused by the inflammation of swollen pouches (diverticula) in the intestinal walls. According to Webmd.com, bleeding can occur when a perforation develops between a blood vessel and diverticular pouch.
  
  

Warning

• In rare instances, bleeding diarrhea can signal a serious condition such as colorectal cancer. Seek help immediately, especially if other symptoms like high fever, vomiting or abdominal pain are present.