Still, authors said other non-steroidal anti-inflammatory drugs should be considered before the use of Diclofenac.
Dr Morten Schmidt, of Aarhus University Hospital in Denmark, is now urging for the drug to come with a warning - and that other countries should copy the United Kingdom and make it prescription only. However, it's actually one of the most popular and routinely recommended drugs sold across the world, in both developing and developed nations.
Now a groundbreaking study of more than six million people, the biggest of its kind, has linked them to "major cardiovascular events".
For years, however, doctors have been anxious about diclofenac's potential heart risks.
The drug has been widely available over the counter in the United Kingdom until recently, when it was withdrawn over fears about serious side effects. The researchers looked at records between 1996 and 2006. According to Daily Mail, many parts of the world - including the United Kingdom - have banned diclofenac as an over-the-counter medication because of its adverse effects on the cardiovascular system.
Researchers behind this study and other studies warn of the risky of taking painkillers.
"It's time to acknowledge the potential health risk of diclofenac and to reduce its use", write Morten Schmidt, M.D., Ph.D., registrar, Henrik Toft Sørensen, M.D., Ph.D., clinical professor and chair, and Lars Pedersen, Ph.D., professor, department of clinical epidemiology, Aarhus University.
While the 50 per cent figure is scary-sounding, it's worth keeping in mind the absolute risk is still fairly small.
The researchers advised that diclofenac should come with front of package warnings about its risks after the study found that patients who started diclofenac were at a 50% increased risk of cardiovascular events - such as heart failure, heart attack or atrial fibrillation - in the 30 days after starting the drug compared with those not taking the drug. For people at high risk of cardiovascular disease, that number would shoot up to 40, with half dying.
This is an observational study, so no firm conclusions can be drawn about cause and effect. But given other research showing a similar heightened risk, the authors say it's clear that diclofenac needs to be more carefully handled, if not phased out of use completely.
Dr Schmidt said: "Treatment of pain and inflammation with NSAIDs may be worthwhile for some patients to improve quality of life despite potential side effects".
The researchers found that starting diclofenac during the study period was linked to increased rate of cardiovascular events such as heart failure, heart attack, irregular heartbeat, and ischaemic stroke within a month compared with starting paracetamol, or other traditional NSAIDs such as ibuprofen or naproxen.