Rectal bleeding may occur for many reasons. Common causes of rectal bleeding include:

1. Anal fissure (a small tear in the lining of the anal canal)
2. Constipation — which can be chronic and last for weeks or longer.
3. Hard stools
4. Hemorrhoids (swollen and inflamed veins in your anus or rectum)

Less common causes of rectal bleeding include:

1. Anal cancer
2. Angiodysplasia (abnormalities in the blood vessels near the intestines)
3. Colon cancer — cancer that starts in the part of the large intestine called the colon.
4. Colon polyps
5. Crohn's disease — which causes tissues in the digestive tract to become inflamed.
6. Diarrhea
7. Diverticulosis (a bulging pouch that forms on the wall of the intestine)
8. Inflammatory bowel disease (IBD)
9. Ischemic colitis (colon inflammation caused by reduced blood flow)
10. Proctitis (inflammation of the lining of the rectum)
11. Pseudomembranous colitis (colon inflammation caused by an infection)
12. Radiation therapy
13. Rectal cancer
14. Solitary rectal ulcer syndrome (ulcer of the rectum)
15. Ulcerative colitis — a disease that causes ulcers and swelling called inflammation in the lining of the large intestine.