Common painkillers taken by millions of Britons can raise the risk of a heart attack by up to 50 percent, researchers have found.
And one, diclofenac, is so dangerous it should not be taken at all, one expert warned.
Others such as ibuprofen, which is sold over the counter in the UK, are not ‘harmless’ and should be used with caution.
Scientists say the pills should not be sold in supermarkets and petrol stations, because there is no professional advice on how to use them.
A study of almost 29,000 patients found any NSAID (non-steroidal anti-inflammatory drug) increased the risk of a cardiac arrest by almost a third (31 percent).
Diclofenac and ibuprofen – taken for back pain, headaches, arthritis, period pains and other ailments – were associated with a 50 percent and 31 percent increased risk, respectively.
The findings follow research last year which showed patients who regularly take the painkillers are up to 20 percent more likely to develop heart failure.
It is believed long-term use of the medications cause chemical reactions in the body which place extra strain on the heart.
Professor Gunnar Gislason, of Copenhagen University Hospital in Denmark, said NSAIDs were among the most commonly used drugs worldwide.
He added: ‘Allowing these drugs to be purchased without a prescription, and without any advice or restrictions, sends a message to the public that they must be safe.
‘Previous studies have shown that NSAIDs are related to increased cardiovascular risk which is a concern because they are widely used.’
The study, published in the European Heart Journal, Cardiovascular Pharmacotherapy, analysed 28,947 patients who had a heart attack outside hospital between 2001 and 2010.
Of these, 3,376 were treated with an NSAID up to 30 days before the event. Ibuprofen and diclofenac were the most commonly used, making up 51 per cent and 22 per cent of the total, respectively.
Prof Gislason said: ‘The findings are a stark reminder that NSAIDs are not harmless. Diclofenac and ibuprofen, both commonly used drugs, were associated with significantly increased risk of cardiac arrest. NSAIDs should be used with caution and for a valid indication.
They should probably be avoided in patients with cardiovascular disease or many cardiovascular risk factors.
‘I don’t think these drugs should be sold in supermarkets or petrol stations where there is no professional advice on how to use them.
Over-the-counter NSAIDs should only be available at pharmacies, in limited quantities, and in low doses.’
He advised patients to take no more than 1,200mg of ibuprofen a day – about six small tablets – and added: ‘Diclofenac is the riskiest NSAID and should be avoided by patients with cardiovascular disease and the general population.
‘Safer drugs are available that have similar painkilling effects.’
Diclofenac is no longer sold over the counter in the UK because of concerns about its effect on the heart. It is available only on prescription.
Prof Gislason said: ‘Our study adds to the evidence about the adverse cardiovascular effects of NSAIDs and confirms that they should be taken seriously, and used only after consulting a healthcare professional.’
The British Heart Foundation says patients should be on the lowest dose possible of NSAIDs for the shortest possible time.