The recommended age to start colonoscopy screening is 45 for adults at average risk of colorectal cancer. The U.S. Preventive Services Task Force lowered this threshold from 50 in 2021, and routine screening is recommended through age 75. If you have a family history or certain symptoms, you may need to start even earlier.
Why Screening Now Starts at 45
Colorectal cancer rates among younger adults have been climbing steadily. Across the U.S., Australia, Canada, and England, cases in people under 50 rose by an average of 3.7% per year over the most recent decade studied. The increase is even sharper in adults under 40, where rates climbed roughly 7% per year. Women are seeing slightly faster increases than men in both age groups.
This trend is what prompted the guideline change. Before 2021, average-risk screening didn’t begin until 50. The new recommendation closes a gap that was leaving a growing number of cancers undetected during a five-year window when early treatment could make a significant difference.
When to Start Earlier Than 45
Family history is the most common reason to begin screening before the general recommendation. If you have one first-degree relative (a parent, sibling, or child) or two second-degree relatives (grandparents, aunts, uncles) who had colon cancer or precancerous polyps, screening should begin at age 40, or 10 years before the youngest case in your family, whichever comes first. So if your mother was diagnosed at 42, your first colonoscopy would be recommended at 32.
People with hereditary colorectal cancer syndromes, such as Lynch syndrome or familial adenomatous polyposis, often begin screening much younger. In some cases, colonoscopies start in childhood or early adulthood and may be repeated annually. If a genetic syndrome runs in your family, a genetic counselor or gastroenterologist can help map out a timeline specific to your risk.
Symptoms That Warrant Screening at Any Age
A National Cancer Institute analysis identified four warning signs that appeared more frequently in younger adults in the months to years before a colorectal cancer diagnosis: abdominal pain, rectal bleeding, diarrhea, and iron deficiency anemia. Having just one of these signs was associated with nearly double the likelihood of an early-onset diagnosis compared to having none. Having three or more was linked to a sixfold increase.
These symptoms don’t automatically mean cancer. They’re common and usually caused by something far less serious. But if any of them persist, keep returning, or you have more than one at the same time, that pattern is worth investigating regardless of your age. A colonoscopy in that context isn’t “screening” in the routine sense. It’s a diagnostic procedure, and age guidelines don’t apply the same way.
When to Stop Screening
Routine screening is recommended through age 75. Between 76 and 85, the decision becomes more individual, weighing factors like your overall health, life expectancy, and whether you’ve been consistently screened in previous years. After 85, screening is generally not recommended because the risks of the procedure begin to outweigh the potential benefits for most people.
How Often You’ll Need a Colonoscopy
Your repeat schedule depends entirely on what the doctor finds during your procedure. If your colonoscopy is completely normal, the next one isn’t needed for 10 years. That’s the best-case scenario and the most common outcome.
If small polyps are found and removed, the timeline shortens:
- 1 to 2 small polyps: repeat in 7 to 10 years
- 3 to 4 small polyps: repeat in 3 to 5 years
- 5 to 10 small polyps: repeat in 3 years
These intervals assume the polyps were completely removed and the exam was high quality, meaning the doctor had a clear view of the entire colon. If prep was poor or the exam was incomplete, you may be asked to come back sooner.
Other Screening Options Besides Colonoscopy
Colonoscopy is the most thorough option, but it’s not the only one. Stool-based tests can detect blood or abnormal DNA shed by polyps and cancers. These are less invasive and done at home, but they need to be repeated more frequently, typically every one to three years depending on the test. The tradeoff is convenience versus sensitivity: if a stool test comes back positive, you’ll need a colonoscopy anyway to follow up.
For people who are up to date and at average risk, any recommended screening method is better than skipping it entirely. The best test is the one you’ll actually complete.
Insurance Coverage for Screening
Under the Affordable Care Act, all Marketplace health plans and most other private insurance plans must cover colorectal cancer screening for adults 45 to 75 at no cost to you. That means no copay, no coinsurance, and no requirement to meet your deductible first, as long as you use an in-network provider. This applies to screening colonoscopies, meaning procedures done for routine prevention rather than to investigate a specific symptom. Diagnostic colonoscopies, ordered because of symptoms or a positive stool test, may be billed differently and could involve cost-sharing depending on your plan.