People taking one of the most common painkillers have been urged to consult their GPs after a study found it could significantly increase risks of heart attacks and strokes.
Those on diclofenac were found to be 40% more at risk than those who were not using the drug, according to research published in Plos Medicine.
Diclofenac was the most commonly prescribed non-steroidal anti-inflammatory drug (NSAID) in England last year, with almost 6m prescriptions written for it. The drug is also available over the counter.
In 2010 almost 17m prescriptions were filled out for NSAIDs, which are used for pain relief and for their anti-inflammatory effects in conditions including arthritis, back pain, gout, headache, and the aches and fever associated with flu.
A team from the Hull York Medical School in England and the Institute for Clinical Evaluative Sciences in Toronto, Canada, analysed 51 international studies into the impact of a range of NSAIDs.
Lead researcher Dr Patricia McGettigan from Hull York Medical School, a joint venture between the Universities of Hull and York and the NHS, said: “NSAIDs provide pain relief for millions of patients with chronic inflammatory disorders. The cardiovascular risk is well described but often overlooked. In choosing which one of the many available NSAIDs to use, patients and doctors would benefit from knowledge of the balance between benefit and harm for individual NSAIDs.
“For example, diclofenac, the NSAID most commonly prescribed in England in 2010, was associated with an increase in cardiovascular risk of 40% (compared with non-use). At high doses, the increase in risk was almost doubled. An alternative, naproxen, prescribed only half as often, was not associated with increased risk at any dose. For the first time we have enough data to make direct comparisons between NSAIDs to determine which are most risky and which are relatively safe.”
McGettigan said “For example, a patient with previous heart problems, high blood pressure and diabetes has an annual background risk of heart attack over 5%, use of diclofenac will increase that by 40%, giving an annual risk of over 7%. In other words, one in 50 such patients might suffer an avoidable heart attack. This is important information in making choices, particularly if there is a safer alternative.
“In contrast, a healthy young woman has an annual risk of heart attack of less than 0.1% – she will experience a negligible increase in cardiovascular risk with any of the commonly used NSAIDs.”
The Medicines and Healthcare products Regulatory Agency (MHRA), which said it kept the safety of such drugs under review, warned patients not to stop taking the drugs but to consult their doctor if they were concerned.
A spokesman said: “All medicines have side effects – no effective medicine is without risk. Our priority is to ensure that the benefits of medication outweigh the risks.
“The safety of all NSAIDs have been carefully evaluated by the MHRA specifically looking at the risk of gastrointestinal and heart problems.
“Clear information about the risk of gastrointestinal and heart problems, along with information about those patient groups in which NSAIDs either should not be used, such as those with severe heart failure, or only used with caution, are contained in the product information including the patient information leaflet that accompanies the medicine.
“To minimise the risk of side effects all NSAIDs should be used at the lowest possible dose for the shortest period necessary to control symptoms.”