Low dose aspirin bleeding risk

Aspirin thins the blood

Even low doses of aspirin can cause internal bleeding in the stomach and intestine, researchers have found.

Many doctors recommend that their patients take aspirin to reduce their risk of heart problems.

The drug thins the blood, and reduces the risk of clots forming in key blood vessels.

Aspirin treatment should be used only when there is good reason to do so

Dr Yoon Kong Loke, Radcliffe Infirmary

It is well known that doses of 300mg a day, which were prescribed in the past, carry a risk of gastrointestinal bleeding.

Some experts thought, however, that low doses of aspirin, such as 75mg a day, carry little risk of side effects.

But this theory has been debunked by scientists at the Radcliffe Infirmary in Oxford, who found that long-term use of the drug, even at low doses, does have potentially harmful side effects.

They also found no evidence that using expensive "modified release" formulations of aspirin reduces the risk of bleeding.

The researchers analysed 24 previous studies of aspirin, involving almost 66,000 patients.

They found that, on average, bleeding occurred in 2.5% of patients taking aspirin compared with 1.4% who were not.

Routine practice

Writing in British Medical Journal, the researchers warn that their findings have important implications for everyday practice as the use of aspirin to prevent heart problems is widespread in the UK.

Patients and doctors need to consider the trade-off between the benefits and harms of long term treatment with aspirin, they say.

Researcher Dr Yoon Kong Loke told BBC News Online: "There is no doubt that aspirin is an effective drug.

"Because of this problem with gut bleeding though, aspirin treatment should be used only when there is good reason to do so."

In an accompanying editorial, Dr Martin Tramer, of Geneva University Hospitals, Switzerland, argues that it is unclear who should be given what dose of aspirin and for how long.

Doctors have been treating their patients with low dose aspirin on the understanding that they did more good than harm, he says.

But it was wrong to make such an assumption until further research was carried out.

A study by researchers at the Wolfson Institute of Preventive Medicine in London published earlier this year found aspirin was linked to a risk of serious bleeding in men with high blood pressure.