A range of common painkillers -- including at least one available without prescription -- significantly increase the risk of stroke in the elderly and should be reserved for cases where extra pain relief is most needed, researchers warned Monday.

In a study published in The Medical Journal of Australia, eight painkilling drugs were tested for their effect in raising stroke rates.

Patients taking the anti-inflammatory medicine diclofenac experienced the third-biggest increase in stroke rates, lifting the rate by 75 percent. Diclofenac, which is sold under a variety of brand names including Voltaren and Imflac, is available at low doses from pharmacies Down Under without prescription.

Two other drugs available without prescription that were included in the study, ibuprofen and naproxen, emerged as the two least likely to raise stroke risk, while diclofenac, celecoxib (Celebrex) and rofecoxib (Vioxx) -- which was withdrawn globally in 2004 after doctors reported a spate of heart attacks among patients taking it -- had the strongest likelihood.

Overall, patients taking any of the eight medicines known collectively as non-steroidal anti-inflammatory drugs were 88 percent more likely to suffer a stroke severe enough to warrant hospitalization, according to the retrospective analysis of hospital admission and prescribing records for more than 160,000 Australian veterans.

The authors of the study, from the University of South Australia and the federal government's Department of Veterans Affairs, said the near-doubling in risk translated to relatively few extra strokes -- an estimated 13.4 per 1000 people annually -- because the risk of stroke was low in the first place, at 7.1 per 1000 annually.

However, they said such "small increases in risk may be particularly important for older people," who tended to have conditions such as cardiovascular disease that left them at a higher risk of stroke than younger people.

Lead author Gillian Caughey said the general public assumed most of the painkillers studied were "harmless -- like taking a Panadol" when, in fact, Australian guidelines recommended they be used at the lowest dose for the shortest possible time.

But stroke specialist Richard Lindley, chairman of the National Stroke Foundation's clinical council, told The Australian the results should be kept in perspective, given that many patients would take the drugs for only a few days.

"If you have osteoarthritis and these drugs are the only things that make you comfortable, I think a lot of people would rather accept the small risk [than live in pain]," he said.

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