Commonly-used painkillers, which are considered harmless by many, may increase the risk of cardiac arrest, a new study has found.

The findings centre on non-steroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen, which are available over the counter.

"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," commented one of the study's authors, Prof Gunnar Gislason, of Copenhagen University Hospital Gentofte in Denmark.

He and his team set out to investigate any potential links between NSAIDs and cardiac arrest.

Cardiac arrest refers to the sudden loss of function of the heart. It occurs when there is an abrupt disturbance in the heart's rhythm, causing the heart to stop beating.

A person whose heart has stopped beating will fall unconscious and stop breathing normally. If they do not get immediate medical assistance, sudden cardiac death will follow. Some 5,000 people die as a result of this every year in Ireland.

The Danish study looked at the almost 29,000 patients who had an out-of-hospital cardiac arrest in Denmark between 2001 and 2010. Data was also collected on all redeemed prescriptions for NSAIDs from Danish pharmacies since 1995.

The study found that overall, the use of any NSAID was linked with a 31% increased risk of cardiac arrest. Specifically, ibuprofen increased the risk by 31%, while diclofenac increased the risk by 50%.

"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," Prof Gislason said.

He believes that these drugs should not be sold in supermarkets or petrol stations ‘where there is no professional advice on how to use them'. Instead, they should only be sold in pharmacies 'in limited quantities and in low doses'.

"The current message being sent to the public about NSAIDs is wrong. If you can buy these drugs in a convenience store then you probably think ‘they must be safe for me'. 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," Dr Gislason added.

Details of these findings are published in European Heart Journal - Cardiovascular Pharmacotherapy.