The popular painkiller naproxen, made by German drug giant Bayer, has the same cardiovascular risks as rival medicines, US regulators say.
Scientists from Oxford University have concluded that naproxen, sold under the brand name Aleve, poses a lesser heart risk than other painkillers.
But a panel of experts assembled by the US Food and Drug Administration (FDA) decided, by a vote of 16 to nine, against softening the warning label on the medication, rejecting the scientists' analysis.
The Oxford researchers formed their conclusion after analysing data from more than 700 studies and some 350,000 patients.
The FDA panel, on the second day of their two-day meeting, nonetheless said the study's evidence is insufficient to warrant exemption from the labels used by rival drugs.
Researchers have found a link between anti-inflammatory medications like ibuprofen and Celebrex and "cardiac events", including heart attack.
The lucrative painkiller market last year generated some $US1.7 billion ($A1.89 billion) in sales, US industry experts said.
