All men and women need a screening colonoscopy at age 50. Screening means you have no symptoms such as rectal bleeding, abdominal pain, change in bowel habits, unexplained weight loss or anemia. People with risk factors such as a family history of colorectal cancer should be checked at 40 and sometimes sooner. If your first colonoscopy is normal without risk factors, a colonoscopy is recommended every 10 years. If you have risk factors including a personal history of colon polyps, more frequent colonoscopies are recommended. People with symptoms might need to be checked before the typical screening guidelines.