For most individuals, colonoscopy screening is recommended starting at age 45, according to guidelines from health organizations such as the American Cancer Society. This recommendation applies to people with an average risk of developing colorectal cancer. However, individuals with higher risk factors, such as a family history of colon cancer, a personal history of inflammatory bowel disease (IBD), or the presence of polyps, may need to start screening earlier, often by age 40 or even sooner. High-risk individuals should consult their healthcare provider for personalized screening recommendations.

In addition to age-based screening, a colonoscopy may be recommended when symptoms like rectal bleeding, persistent abdominal pain, unexplained weight loss, or changes in bowel habits occur. These symptoms can be signs of underlying gastrointestinal issues, including cancer or other serious conditions. Regular colonoscopies help in detecting colon abnormalities early, significantly increasing the chances of successful treatment. After the first screening, follow-up colonoscopies are generally advised every 10 years for those with no significant findings, but the interval may be shorter for those with a history of polyps or other risk factors.