For most people at average risk, routine colorectal‑cancer screening (including colonoscopy) now starts at age 45 and continues through your mid‑70s, with many guidelines stopping routine screening around age 75, depending on health and prior findings.

Current general guidelines

  • Major groups like the U.S. Preventive Services Task Force and the American Cancer Society recommend starting colorectal‑cancer screening at age 45 for average‑risk adults.
  • If your first colonoscopy is normal and you remain low‑risk, repeat screening is typically every 10 years; abnormal findings may shorten that interval.

When to start earlier than 45

Several organizations advise earlier screening if you have:

  • A family history of colorectal cancer or large polyps, often starting around age 40, or 10 years before the relative’s diagnosis if that’s earlier.
  • Certain inherited syndromes (for example Lynch syndrome or familial adenomatous polyposis) or inflammatory bowel disease; in these cases, first screening may begin in the 20s or as soon as diagnosis is confirmed.

Special age‑group notes

  • Some guidelines suggest slightly earlier or more tailored screening for Black adults (for example at 45 or in certain high‑risk groups starting closer to 40), reflecting higher incidence and earlier onset.
  • For older adults (over about 75), guidelines generally say screening decisions should be individualized based on life expectancy, prior screen results, and comorbidities rather than a fixed age cutoff.

Screening “routine” by risk level (summary table)

Risk category| Suggested first screening age| Typical repeat interval
---|---|---
Average risk (no family history, no symptoms)| Age 45 139| Every 10 years if normal 19
Family history of CRC (one relative)| Around 40, or 10 years before relative’s diagnosis 579| Often every 5 years 59
High‑risk syndromes or IBD| Late teens to 20s, as advised by gastroenterologist 59| Usually every 1–3 years 9

Practical takeaway

If you’re under 45 but have a close relative with colon cancer, unexplained rectal bleeding, long‑standing diarrhea or constipation, or significant weight loss, you should discuss earlier or “targeted” testing (which may or may not be a colonoscopy) with your primary‑care doctor or gastroenterologist.

Information gathered from public forums or data available on the internet and portrayed here.