There are many myths about colonoscopies that often prevent people from getting a colon cancer screening when they should. Just when should you get a colonoscopy? If you’re of normal risk then screenings should begin at age 50 for both men and women. African-Americans are at a higher risk for colon cancer so typically the screening age begins at 45. If you have a history of colon cancer in your family, speak with your physician about when to begin.