Daily aspirin linked to increased risk of stroke and will NOT protect you against bowel cancer, experts claim

New research finds aspirin does not provide a quick or guaranteed way to prevent bowel cancer and carries the risk of serious bleeding associated with a rare type of stroke.

The findings, published in the Cochrane Database of Systematic Reviews, are based on evidence from 10 randomized clinical trials.

Researchers from West China Hospital of Sichuan University analyzed data from 124,837 participants to evaluate whether aspirin prevented bowel cancer or precancerous polyps in people at average risk.

Their review found that aspirin was unlikely to reduce the risk of bowel cancer during the first five to 15 years of use, but possible protective effects were observed after more than 10 to 15 years of follow-up in some studies.

These potential long-term benefits come from the observational follow-up phases of the studies, where participants may have discontinued aspirin, started it independently, or started other treatments, making the findings vulnerable to bias.

Dr Zhaolun Cai, lead author of the study, said: ‘While the idea that aspirin could prevent bowel cancer in the long term is intriguing, our analysis shows that this benefit is not guaranteed and comes with immediate risks.’

The findings also suggest that daily aspirin use increases the risk of serious extracranial bleeding, when a hemorrhage occurs between the skull and scalp, and hemorrhagic stroke, which occurs when a blood vessel in the brain bursts and its contents begin to leak into the organ.

Although higher doses carry the greatest risk, low-dose (‘baby’) aspirin also increases the risk of bleeding, and older adults and those with a history of ulcers or bleeding disorders may be particularly vulnerable.

The authors warn that any potential long-term benefit of aspirin must be weighed against the risk of immediate and radical bleeding.

Senior author Dr. “My biggest concern is that people think that taking aspirin today will protect them from cancer tomorrow,” Bo Zhang said.

‘In reality, it would take more than a decade for any potential preventive effect to emerge, if at all, but the risk of bleeding begins immediately.’

Previous evidence has shown potential benefits for people at high genetic risk for colorectal cancer, such as people with Lynch syndrome. However, this review focuses strictly on people at average risk, and the long-term evidence for them turns out to be quite uncertain.

In recent years, researchers have investigated the role of off-the-shelf medications such as ibuprofen and aspirin. in reducing bowel cancer.

Aspirin works by stopping the body from producing a type of hormone called prostaglandin, which sends pain signals to the brain.

Therefore, taking aspirin reduces pain, reduces swelling and high fever.

In a 2025 study published in the New England Journal of Medicine, Swedish researchers found that people who took low-dose daily aspirin after their tumors were removed had half the chance of their cancer returning within the next three years.

However, their role in the primary prevention of bowel cancer is unclear and controversial.

The authors suggest that patients should not start taking aspirin to prevent cancer without carefully discussing their personal bleeding risks with their healthcare provider.

Senior author Dr. ‘This review reinforces the need to move away from a one-size-fits-all approach,’ said Dan Cao.

‘Widespread aspirin use in the general population is not supported by evidence. ‘The future lies in precision prevention, using molecular markers and individual risk profiles to identify who may benefit most and who is most at risk.’

The research team concludes that aspirin’s history of cancer prevention is much more complex than previously believed, and that the balance of benefits and harms changes over time.

“As scientists, we must follow the evidence where it leads,” Dr Zhang said.

“Our rigorous analysis of the highest quality trials reveals that the ‘aspirin for cancer prevention’ story is more complex than a simple ‘yes or no’.”

‘Current evidence does not support a general recommendation to use aspirin solely to prevent bowel cancer.’

Bowel cancer, also known as colorectal cancer, is one of the most common types of cancer in the UK.

Rates of bowel cancer are rising in people under 50 worldwide, and although the causes are unclear, scientists suspect junk food, obesity, lack of physical activity and toxins produced by gut bacteria play a role.

Prevention typically includes following a healthy lifestyle and undergoing routine screening tests.