Colon polyps usually do not cause symptoms unless they are larger than 1cm or they are cancerous. The most common symptom is rectal bleeding. Sometimes the bleeding may not be obvious (occult) and may only be discovered after doing a screening test for blood in the stool called a fecal occult blood test (FOBT).

Colon polyps usually do not cause pain or a change in bowel habits unless they are large and are blocking part of the colon. These symptoms are rare because polyps usually are discovered and removed before they become large enough to cause problems.

Once cancer develops, additional symptoms also may occur, such as changes in bowel habits and significant weight loss.