Most adults should start routine colonoscopy screening for colorectal cancer at age 45 if they are at average risk, and continue until about age 75, as long as they are in good health.

Basic age guidelines

  • Start at 45 for average‑risk adults (no strong family history, no inflammatory bowel disease, no genetic syndromes).
  • Repeat every 10 years if results are normal and you remain average risk (other stool tests may be done more often instead).
  • Ages 45–75: regular screening is strongly recommended because the benefit is high.
  • Ages 76–85: screening is individualized based on overall health, prior results, and life expectancy.
  • Over 85: screening is generally stopped.

When to start earlier

You may need screening before 45 if you have:

  • A first‑degree relative (parent, sibling, child) with colorectal cancer or advanced polyps, especially if diagnosed before 60. Guidelines often suggest starting at 40, or 10 years before that family member’s diagnosis, whichever comes first.
  • Certain genetic syndromes (like Lynch syndrome or familial adenomatous polyposis).
  • Long‑standing inflammatory bowel disease (ulcerative colitis, Crohn’s colitis).

In these situations, timing and frequency are more aggressive and should be set with a gastroenterologist.

Why the age dropped from 50 to 45

  • Colorectal cancer is increasingly diagnosed in people under 50, with rising early‑onset cases.
  • Modeling studies show that starting at 45 prevents more cancers and deaths with an acceptable increase in colonoscopies.
  • Major groups like the American Cancer Society and the U.S. Preventive Services Task Force now recommend starting at 45 for average‑risk adults.

Simple rule of thumb

  • If you are 45 or older and never screened: talk to your doctor now about getting a colonoscopy or another approved colorectal cancer screening test. Do not wait for symptoms like bleeding, weight loss, or anemia.
  • If you are younger than 45 but have family history or other risk factors: ask specifically whether you should start earlier and how often you should repeat it.

This information is general and cannot replace a personal recommendation from your own clinician. If you’re unsure when you personally should start, bring up your age, family history, and any bowel symptoms at your next visit.

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