Long-term paracetamol use – usually prescribed for the treatment of chronic pain – could increase the risk of heart disease and strokes in people with high blood pressure, a well-designed clinical trial has found.

The researchers say this would amount to an increased risk of heart disease or stroke by about 20 per cent.

They recommend a review of long-term prescribing of the popular pain killer.

Why this is a complex problem

Although the study needs to be backed up by further research, this potentially creates a real quandary – because paracetamol is generally considered to be one of the few safe options as a daily treatment for chronic pain, which affects one of five Australians over the age of 45.

It just so happens that over the course of a year, one in five Australians over the age of 45 will be prescribed at least one opioid – which is probably the least desirable option given prescription opioids kill more people, and put more people in hospitals, than heroin.

Another reason why paracetamol has become the safer option for chronic pain is that non-steroidal anti-inflammatory drugs, such as ibuprofen, are known to increase blood pressure and risk of heart disease.

Now paracetamol appears to have the same problem, at least in people prone to hypertension (high blood pressure) – which affects one in three Australians over the age of 18.

The prevalence of hypertension steadily rises with age.

The new study

The new study is from University of Edinburgh clinical pharmacologist Professor James Dear.

In the randomised clinical trial 110 patients with a history of high blood pressure were prescribed one gram of paracetamol four times a day – a routinely prescribed dose in patients with chronic pain – or a matched placebo for two weeks.

All patients received both treatments, with the order randomised and blinded, so they didn’t know which pill they were getting.

Those prescribed paracetamol “saw a significant increase in their blood pressure, compared with those taking the placebo”.

This rise was similar to that seen “with non-steroidal anti-inflammatory drugs, and might be expected to increase the risk of heart disease or stroke by around 20 per cent”.

These conclusions were previously made in observational studies.

The researchers say their findings warrant a review of long-term paracetamol prescriptions to patients – particularly those with high blood pressure, or those at particular risk of heart disease or stroke.

The authors write: “This study clearly shows that paracetamol – the world’s most-used drug – increases blood pressure, one of the most important risk factors for heart attacks and strokes.

“Doctors and patients together should consider the risks versus the benefits of long-term paracetamol prescription, especially in patients at risk of cardiovascular disease.”

The authors note that “this is not about short-term use of paracetamol for headaches or fever which is, of course, fine”.

However, as The New Daily reported last year, a University of Sydney review found “there is no good evidence that the drug is actually effective against many ailments”.

One of the authors of that review told The New Daily that paracetamol “would not be approved if brought to market today”.