🧡 Aspirin and Lynch Syndrome: Your Questions Answered

At Lynch Syndrome UK, we know that many families have questions about aspirin and its role in cancer prevention. Recent research — especially the CaPP3 trial — has given us new guidance, but it’s natural to want clarity on how this applies to everyday life.

Together with clinicians from the UK National Lynch Syndrome Network and input from our community, we’ve gathered the most frequently asked questions and answers to help you feel informed and supported.

🌱 Why might I be advised to take aspirin?

Research shows that regular aspirin use reduces the risk of bowel cancer and possibly other cancers in people with Lynch syndrome. The earlier CaPP2 trial proved this benefit, and CaPP3 has now refined the recommended dose.

💊 What dose should I take?

The CaPP3 trial found that the right dose depends on body mass index (BMI):

• BMI under 30: 75 mg daily

• BMI 30 or more: 150 mg daily

If you’ve been taking a higher dose, it’s reasonable to reduce it now. Always check with your GP or Lynch syndrome specialist before making changes.

🕐 When should I start, and for how long?

• Start aspirin around 5 years before your recommended colonoscopy age (around 20 for MLH1/MSH2/EPCAM, around 30 for MSH6/PMS2).

• The protective effect appears after at least 2 years of regular use. Current guidance suggests aiming for 5 years or more, reviewed by your specialist.

• Most people are advised to stop by age 70, and not to start after 65 unless there’s another medical reason.

🩺 Do I need tests before starting?

Yes. Your GP can arrange a Helicobacter pylori test (usually a stool test). If the bacteria is present, it should be treated before starting aspirin to reduce stomach irritation and lower stomach cancer risk.

⚠️ What are the possible side effects?

Most people tolerate aspirin well, but side effects can include:

• Stomach pain or indigestion

• Easy bruising or bleeding

• Rarely, ulcers or allergic reactions

If you’ve had problems before, solutions may include a lower dose, coated tablets, or protective medication. Always discuss with your doctor.

🚫 Who should not take aspirin?

Aspirin may not be suitable if you:

• Have a history of stomach ulcers or bleeding

• Have asthma triggered by aspirin or NSAIDs

• Take blood-thinning medicines

• Have a bleeding disorder

• Are under 18 (unless advised by a specialist)

🔄 What if I forget a dose?

Simply take your usual dose the next day. Don’t double up.

🧾 Do I still need regular screening?

Yes! Aspirin is not a substitute for colonoscopy or other recommended checks. It should be used alongside your NHS surveillance plan.

👩‍⚕️ Other common questions

• Colonoscopy: Aspirin does not usually need to be stopped.

• Surgery: It may be paused temporarily — discuss with your surgeon.

• Other medicines: Some drugs interact with aspirin, so review your list with your GP or pharmacist.

• Pregnancy: Aspirin may be safe in some circumstances, but always check with your GP or obstetric team.

🌍 Final Thoughts

The CaPP3 trial has given us confidence that low-dose aspirin is effective and safe for people with Lynch syndrome. But every person’s situation is unique. That’s why it’s vital to talk with your GP or specialist before starting, stopping, or changing your dose.

At Lynch Syndrome UK, we’re here to make sure you have the information, reassurance, and support you need. Together, we can turn research into real-world prevention.

📄 Want a handy document to share with your GP or specialist?

Download the full Aspirin and Lynch Syndrome Frequently Asked Questions PDF below.

Aspirin and Lynch Syndrome FAQ Nov 2025.pdf

Download PDF • 123KB