50 unless... The general guideline is age 50, but there are exceptions to that rule. For example, family history of colon cancer can move up the schedule.
Depends on age. If routine colonoscopy for average person without any alarming symptoms or family history is 50 years old.
Screening guidelines. Much study has gone into the recommendations. For routine screening of an average risk american, begin at 50 and repeat every 10 years. If you have additional risk factors, begin earlier. Typically if you have a family member with colon polyps or colon cancer, you might begin earlier. African americans should start at 45. If you have symptoms, you may need a test outside the screening guides.