"Using aspirin daily can help prevent heart attacks and stroke in some [cases], but it can also cause serious adverse effects such as internal bleeding,” said John Wong, a member of the US Preventive Services task force, quoted in a statement.

This is a turnaround on the subject, which concerns millions of American citizens, since it is a widespread practice in the US.

Cardiovascular disease is the leading cause of death in the United States.

For their part, people aged 40 and 59 at risk, but without a history of cardiovascular disease, should make the decision to start treatment individually, together with doctors, added the experts.

"It's important that people between 40 and 59 who have no history of heart disease talk to their doctor to decide together whether it's okay to take aspirin," said John Wong.

Since 2016, experts from the US Preventive Services 'task force', whose recommendations are widely followed, have advised aspirin for people in their 50s with a 10% risk of suffering a heart attack or stroke in the next 10 years.

Experts also believed that at-risk people in their 60s could undertake this prevention treatment based on a personal decision.

But for several years, investigations have called into question the US recommendations.

Aspirin thins the blood, which prevents blood clots from forming and helps reduce the risk of a heart attack or stroke.

Today, however, experts realized that these benefits were not enough to – in older people – offset the increased risk of bleeding, especially in the brain or intestines.

The new recommendations are not yet final and are still subject to a period of public debate until early November.

The task force statement adds that the new recommendations do not apply to people who take aspirin after they have already suffered a stroke or heart attack.

It is estimated that around 600,000 Americans suffer a first heart attack and that around 610,000 suffer their first stroke each year.

The use of aspirin to reduce the risk of cardiovascular disease is often spontaneously initiated by Americans. According to a 2017 study, 23.4% used aspirin.