Long-term paracetamol use may increase the risk of heart disease and stroke in people with high blood pressure, a study has found.
Patients who have a long-term prescription for the painkiller, typically used for the treatment of chronic pain, should opt for the lowest effective dose for the shortest duration possible, the researchers said.
The University of Edinburgh study, published in the scientific journal Circulation, is the first large randomized clinical trial to address the issue and complements previous work in observational studies.
Paracetamol has often been considered a safer alternative to another class of painkillers called nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, which have long been known to increase blood pressure and the risk of heart disease.
In the study, 110 patients with a history of high blood pressure were prescribed 1 g 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, the order being randomized and blinded.
Those taking paracetamol had a significant increase in blood pressure, compared to those taking the placebo. This increase was similar to that seen with NSAIDs and could be expected to increase the risk of heart disease or stroke by around 20%, experts say.
Principal investigator Dr Iain MacIntyre, consultant in clinical pharmacology and nephrology at NHS Lothian, said: ‘This is not a short-term use of paracetamol for headache or fever, it which is, of course, fine – but it does point to a newly discovered risk for people who take it regularly over the longer term, usually for chronic pain.
Professor James Dear, Personal Director of Clinical Pharmacology at Edinburgh, added: “This study clearly shows that paracetamol – the world’s most widely used drug – raises blood pressure, one of the strongest risk factors for seizures. heart attacks and strokes. Physicians and patients should together consider the risks versus benefits of long-term prescription of paracetamol, especially in patients at risk for cardiovascular disease.
The study found that after people stopped taking the drug, their blood pressure returned to what it was at the start of the study. The researchers said they did not have precise figures on people in the UK taking paracetamol long-term and suffering from high blood pressure. But it is estimated that one in three adults in the UK have high blood pressure, increasing with age, while one in 10 people in Scotland – where the research was carried out – regularly take paracetamol.
There were limitations to the study. It only involved 110 people, it didn’t look at patients with chronic pain, and the results don’t reveal anything specific about what might happen in people who didn’t have high blood pressure to begin with.
Professor Sir Nilesh Samani, medical director of the British Heart Foundation, which funded the study, said the research has shown “how quickly regular use of paracetamol can raise blood pressure in people with hypertension who are already at increased risk of heart attacks and strokes.” .
However, he also pointed out: “If you occasionally take paracetamol to manage an isolated headache or very short periods of pain, these research results should not worry you unnecessarily.”