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 Trafficis the first large randomized clinical trial to address this issue and complements previous work in observational studies.
Paracetamol has often been suggested as a safer alternative to another class of painkillers called nonsteroidal anti-inflammatory drugs (NSAIDs), known to increase blood pressure and the risk of heart disease.
In the latest study, 110 patients with a history of high blood pressure were prescribed one gram of paracetamol four times a day – a dose commonly prescribed to patients with chronic pain – or a matching placebo for two weeks. All patients received both treatments, the order being randomized and blinded.
People who were prescribed paracetamol saw their blood pressure rise significantly, compared to those who took 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.
The research team say the findings should lead to a review of long-term paracetamol prescriptions for patients – particularly those with high blood pressure or those at particular risk of heart disease or stroke.
Lead researcher 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, which is , of course, fine – but it does point to a newly discovered risk for people who take it regularly over the long term, usually for chronic pain.
Professor James Dear, Personal Director of Clinical Pharmacology at the University of Edinburgh, said: “This study clearly shows that paracetamol – the world’s most widely used drug – raises blood pressure, one of the risk factors most important for 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.
Lead researcher Professor David Webb, Chair of Therapeutics and Clinical Pharmacology at the University of Edinburgh, also said: ‘We recommend that clinicians start with a low dose of paracetamol and increase the dose by steps, without going any higher than necessary to control the pain. . Given the substantial increases in blood pressure observed in some of our patients, it may be beneficial for clinicians to monitor blood pressure more closely in people with high blood pressure who are starting paracetamol for chronic pain.
Professor Sir Nilesh Samani, Medical Director of the British Heart Foundation, which funded the study, said: “This research shows how quickly regular use of paracetamol can raise blood pressure in people with hypertension who already have an increased risk of heart attacks and strokes. It highlights why doctors and patients should regularly check whether there is a continued need to take medication, even something that may seem relatively harmless like paracetamol, and always weigh the benefits against the risks. However, if you occasionally take paracetamol to manage an isolated headache or very short periods of pain, these research results should not worry you unnecessarily.
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