There are many causes ranging from harmless illness to life threatening disease conditions. Usually the blood will be bright red if the bleeding is from the site closer to the anus or if it flows freely and rapidly from the small intestine; if the blood remains in the gut for a longer time without getting passed in stools then the bacteria break down the blood cells and cause the black colour so is the reason the stools are black in colour sometimes

Common Causes:

• Smoking, Regular alcohol intake, chewing of betel leaves or tobacco
• Eating of spicy food and oily food
• Stress, strenuous exercise can sometimes cause
• Injury during an accident or fall or any stab with sharp objects causing damage to the gut or abdomen
• Intake of any medicines or Drugs

Intestinal Infections:

• Food poisoning or amoebic dysentery by organisms such as Campylobacter, E coli, Salmonella, Shigella
• Ulcerative colitis, Crohn’s disease, Inflammatory bowel disease, Gastroenteritis
• Worm infestations
• Diverticulitis, Viral infections in immunocompromised persons

Anal Lesions:

• Fissure in ano
• Piles or hemorrhoids
• Rectal injury

Other causes:

• Peptic ulcer
• Colonic cancer or stomach cancer or Blood cancer
• Colonal polyps
• Tuberculous infection, Jaundice or Bleeding disorders