Researchers from the UK and Canada say Voltaren should be pulled off the market because it raises the risk of heart attack and stroke.
The painkiller diclofenac, sold as Voltaren, should be taken off the market, the research said, after finding it remains popular despite known cardiovascular risks.
But Medsafe in New Zealand said the danger had been reviewed and it was believed the benefits outweighed the risk.
In a study published this week in the journal PLOS Medicine researchers found that diclofenac, on average, was the most commonly used non-steroidal anti-inflammatory drug (NSAID) in 15 countries studied - despite being associated with more cardiovascular complications than other NSAIDs. Researchers looked at the national essential medicine lists from 100 countries, and found 74 of them listed diclofenac.
The researchers said it was likely that diclofenac was taken by many individuals at high risk of heart attack.