Regular use of commonly prescribed painkillers can increase the risk of a heart attack as early as in the first week of use and especially within the first month of taking high doses, suggests a study.The use of non-steroidal anti-inflammatory drugs (NSAIDs) to treat pain and inflammation can increase the risk of a heart attack from about 20 to 50 per cent, the researchers warned.The study, published in the journal The BMJ, found that taking any dose of NSAIDs -- such as ibuprofen, diclofenac, celecoxib and naproxen-- for one week, one month or more than a month was associated with an increased risk of heart attack."Given that the onset of risk of acute myocardial infarction occurred in the first week and appeared greatest in the first month of treatment with higher doses, prescribers should consider weighing the risks and benefits of NSAIDs before instituting treatment, particularly for higher doses," said Michele Bally from the University of Montreal.For their study, the researchers carried out a systematic review and a meta-analysis and analysed results on 446,763 people of whom 61,460 had a heart attack.