Long-term use of paracetamol – usually prescribed for the treatment of chronic pain – may increase the risk of heart disease and stroke in people with high blood pressure, according to a well-designed clinical trial.
Researchers say this would equate to an increased risk of heart disease or stroke of around 20%.
They recommend a review of the popular painkiller’s long-term prescription.
Why this is a complex problem
Although the study needs to be backed up by further research, it potentially creates a real dilemma – as paracetamol is generally seen as one of the few safe options as a daily treatment for chronic pain, which affects one in five Australians over 45.
It turns out 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 that prescription opioids kill more than people and sends more people to hospitals, than heroin.
Another reason paracetamol has become the safest option for chronic pain is that nonsteroidal anti-inflammatory drugs, such as ibuprofen, are known to increase blood pressure and the 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 increases steadily with age.
The new study
The new study comes from University of Edinburgh Professor of Clinical Pharmacology, Professor James Dear.
In the randomized clinical trial, 110 patients with a history of high blood pressure were prescribed one gram of paracetamol four times a day – a dose commonly prescribed in patients with chronic pain – or a matching placebo for two weeks.
All patients received both treatments, with the order randomized and blinded so they did not know which pill they were receiving.
Those taking paracetamol “saw a significant increase in blood pressure, compared to those taking the placebo”.
This increase was similar to that seen “with nonsteroidal anti-inflammatory drugs, and would be expected to increase the risk of heart disease or stroke by about 20%”.
These conclusions have already been drawn in observational studies.
The researchers say their findings warrant a review of long-term paracetamol prescriptions for patients – especially 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 most widely used drug in the world – raises blood pressure, one of the most important risk factors for heart attacks and strokes.
“Physicians and patients should together consider the risks versus benefits of prescribing paracetamol long-term, particularly in patients at risk for cardiovascular disease.”
The authors note that “this is not for short-term use of paracetamol for headaches or fever which is, of course, fine.”
However, as The new daily reported last year, a study from the University of Sydney found “there is no strong evidence that the drug is actually effective for many ailments”.
One of the review authors said The new daily that paracetamol “would not be approved if it were marketed today”.