A popular painkiller should be banned worldwide because it raises the risk of heart attack and stroke by almost half, joint British and Canadian researchers academics say.
Risks from diclofenac, widely sold as Voltaren, were highest in those who used it regularly, and safer options were available, they said.
Medsafe in New Zealand said it would consider the research, but noted previous reviews had shown the drug's benefits outweighed potential risks.
Group manager Stewart Jessamine said all medicines came with risks.
"In 2008 Medsafe reviewed the safety of non-selective non-steroidal anti-inflammatory drugs (NSAID), such as diclofenac and concluded that the benefits of using diclofenac to treat pain and/or inflammatory conditions outweigh the potential risks for the majority of patients," he said.
Diclofenac is often prescribed after surgery or to combat arthritic pain when other painkillers are not strong enough.
"Medsafe's advice for consumers is to use the lowest possible dose of diclofenac for the shortest time possible and discuss any concerns you may have with your doctor," Jessamine said.
Diclofenac is the most-widely prescribed anti-inflammatory in the world and has been available in New Zealand for more than 20 years.
It is subsidised by state drug-buying agency Pharmac, with 375,000 people being prescribed it in the year ending November 2012. That figure does not include those who buy it over the counter.
Research author David Henry, of the Institute for Clinical Evaluative Sciences in Toronto, has reportedly said the drug was "no doubt" the cause of many deaths.
"If you look at it internationally, diclofenac is the single most widely used NSAID," he said.
"Clearly thousands of people die as a result of using [diclofenac]," Henry said.
"But these are invisible victims. And therefore, there's no advocacy lobby group on their behalf."
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