How Often Should You Get a Colonoscopy?

Most people know they’re supposed to get a colonoscopy at some point. Fewer actually do. It sits in that particular category of health tasks — important, not urgent, easy to defer — until one day you realise it’s been on the list for years.

That gap matters. Colorectal cancer is one of the most common cancers in adults, and one of the most preventable. Not because colonoscopies are magic, but because they catch the problem before it becomes one. Polyps — the small growths that can, over time, become cancerous — are removed during the procedure itself. The screening and the intervention happen in the same appointment.

Understanding how often you actually need one makes it easier to stop deferring.

What a colonoscopy is looking for

A colonoscopy lets a doctor examine the full length of the colon and rectum using a thin, flexible camera. The goal isn’t to find cancer — it’s to find polyps before they get that far.

Colorectal polyps typically take 10 to 15 years to develop into cancer. That biology is why the standard interval between colonoscopies is 10 years for average-risk adults with a normal result. You’re catching the next generation of polyps well before they have time to progress.

If polyps are found and removed, the interval shortens. The more polyps, and the more advanced they are, the sooner the next check is recommended.

How often: what current guidelines say

In the US, the USPSTF updated its colorectal cancer screening recommendations in 2021, lowering the recommended starting age from 50 to 45 for average-risk adults. This change reflected growing evidence that rates of colorectal cancer in adults under 50 have been rising.

In the UK, the NHS bowel cancer screening programme currently invites adults aged 50 to 74 to complete a home stool test (FIT test) every two years. Colonoscopy is offered when that test returns an abnormal result, or for people at higher risk.

The difference in starting age between the US and UK guidelines reflects how each system weighs population-level benefits against the cost and risk of more procedures — not a disagreement about the biology. Both approaches aim to catch the same thing; they differ in strategy.

For most adults, the framework looks like this:

Situation	Recommended interval
Average risk, normal result	Every 10 years from age 45 (US) / 50 (UK)
1–2 small polyps removed	Every 5–7 years
3+ polyps or larger polyps	Every 3 years
Family history of colorectal cancer	Earlier start, often age 40 or 10 years before youngest affected relative
Personal history of colorectal cancer	As directed by your specialist
Inflammatory bowel disease (IBD)	As directed by your specialist — often more frequent

These are general frameworks. Your doctor will determine the right interval based on your specific findings and history.

Why the interval depends on what they find

Not all polyps are the same. Small, sessile polyps (flat, under 10mm) carry a different risk profile than large, advanced adenomas. The number of polyps also matters — finding three or more is treated differently than finding one.

When a colonoscopy comes back completely clear, the 10-year interval is well-supported by evidence. The logic: if the colon was normal at this check, new polyps would need nearly a decade to reach a stage worth acting on. Returning sooner doesn’t improve outcomes — it increases costs and the (small) risks associated with the procedure itself.

This is one of the clearest examples of why over-screening can cause harm as well as good — more frequent testing isn’t always better, and the right interval is one calibrated to actual risk.

Who needs to start earlier

For most people, 45 is the starting point. But some groups are advised to start sooner:

• Family history: If a first-degree relative (parent, sibling, child) was diagnosed with colorectal cancer or advanced polyps before age 60, most guidelines recommend starting screening at age 40, or 10 years before their diagnosis — whichever comes first.
• Genetic conditions: People with Lynch syndrome or familial adenomatous polyposis (FAP) need colonoscopies much earlier and more frequently — this is managed by a specialist.
• Personal history of IBD: Ulcerative colitis and Crohn’s disease affecting the colon raise long-term cancer risk. Frequency is determined by your gastroenterologist.
• Symptoms: Rectal bleeding, unexplained changes in bowel habits, or anaemia without a clear cause warrant investigation regardless of age or screening schedule.

If any of these apply to you, the standard age recommendations don’t apply — discuss your situation directly with your doctor.

Alternatives to colonoscopy

Colonoscopy is the most thorough option, but it’s not the only one. Other tests are used in different countries and contexts:

• FIT test (Faecal Immunochemical Test): A home stool test that detects blood in the stool. Non-invasive, done every 1–2 years. Used as the primary screening tool in the UK NHS programme.
• CT colonography (virtual colonoscopy): A CT scan of the colon. Less invasive than standard colonoscopy, but any polyps found still require a traditional colonoscopy for removal.
• Flexible sigmoidoscopy: Examines only the lower part of the colon. Less thorough than a full colonoscopy.

Each has trade-offs in terms of accuracy, invasiveness, and what happens next if something is found. Colonoscopy remains the gold standard because it combines detection and treatment in one procedure.

Keeping track of when you’re due

One of the less-discussed problems with colonoscopy screening is simply remembering when you last had one — and when you’re next due. A 10-year interval is long enough that the appointment easily gets lost. People change doctors. Records don’t always follow.

Keeping a note of your last colonoscopy date and your recommended next interval means you’re not relying on someone else to flag it. If you’re building a broader picture of which check-ups apply to you at your age, our complete adult screening guide covers the full landscape by decade. Screening Clearing is a free iOS and Android app for tracking personal health screening schedules — it lets you log your last colonoscopy date and shows you when the next one is due, alongside your other check-ups.

Frequently Asked Questions

At what age should you have your first colonoscopy?

Most US guidelines recommend starting at age 45 for average-risk adults, following a 2021 update from the USPSTF. In the UK, the NHS bowel screening programme starts at 50 using a home stool test, with colonoscopy offered for higher-risk individuals or abnormal results. If you have a family history of colorectal cancer or certain genetic conditions, your doctor may recommend starting earlier.

How often do you need a colonoscopy after 50?

For average-risk adults with a normal result, every 10 years is the standard recommendation. If polyps were found and removed, the interval shortens to 3–7 years depending on the type and number of polyps. Your doctor will advise the appropriate interval based on your specific findings.

Can you have a colonoscopy too often?

Yes. Colonoscopy carries a small but real risk — including a rare risk of bowel perforation — and more frequent testing than necessary increases that risk without improving outcomes. The recommended intervals are evidence-based: they're designed to catch problems in time while avoiding unnecessary procedures. Following your doctor's recommended interval rather than going more frequently is the right approach for most people.

What happens if polyps are found during a colonoscopy?

Polyps are usually removed during the same procedure. Your follow-up interval will then depend on the number, size, and type of polyps found. Small, low-risk polyps typically mean a 5–7 year follow-up. Larger or more advanced polyps may require a follow-up in 3 years. Your doctor or specialist will give you a specific recommendation based on the pathology report.

Does family history change how often you need a colonoscopy?

Yes. If a first-degree relative (parent, sibling, or child) was diagnosed with colorectal cancer or advanced polyps before age 60, guidelines generally recommend starting screening at age 40, or 10 years before their diagnosis — whichever is earlier. The interval may also be shorter than the standard 10 years. Guidelines vary by country and individual circumstances, so discuss your family history with your doctor.