The use of common painkillers or non-steroidal anti-inflammatory drugs (NSAIDs) for a long time can result in a small yet significant risk of having heart attacks, a new study from the University of Oxford says.

For the study, researchers analyzed 639 clinical trials that included more than 350,000 people.

The researchers found that high doses of diclofenac (150 mg per day) or ibuprofen (more than 2,400 mg per day) increased the risk of heart attacks, stroke, or dying of cardiovascular diseases by about a third. However, another painkiller - naproxen - wasn't associated with any increased risk of heart attacks.

"The research shows that, when used in high doses, diclofenac and ibuprofen increase the risk of cardiovascular disease, on average causing about 3 extra heart attacks a year in every 1000 patients treated, one of which would be fatal," said professor Colin Baigent of Oxford's Clinical Trial Service Unit.

A lot of these painkillers have been in the market for many years. It is only recently that researchers have found that the newer class of NSAIDs, called the COX-2 inhibitors or coxibs, increases the risk of heart attacks.

Researchers said that the risk is higher only for people who take high doses of these drugs for extended periods of time. Health experts have previously said that patients shouldn't stop taking the drugs and must instead consult their doctors.

"We would emphasise that the risks are mainly relevant to people with arthritis who need to take high doses over a long period. A short course of lower dose tablets purchased without a prescription, for example for a muscle sprain, is not likely to be hazardous," added Baigent in a news release.

The study is published in the journal The Lancet.                                          

Previous research in the journal Cancer had reported that over-the-counter painkillers like aspirin, ibuprofen and naproxen might protect against skin cancer.