Painkillers could increase a person’s chances of going into cardiac arrest, according to new research published in Cardiovascular Pharmacotherapy, a European heart journal. Several painkillers ibuprofen, which are classified as a non-steroidal anti-inflammatory drugs, commonly known as NSAIDs, can be bought from chemists without prescriptions. These drugs are associated with a 31% increased risk of cardiac arrest.

The study investigated the link between NSAID use and cardiac arrest by analysing the medical conditions of 28,947 patients from Denmark who suffered a cardiac arrest. The research team checked the study subjects’ consumption of painkiller and found that 3,376 were treated with an NSAIDs up to 30 days before their heart attacks.

They found that diclofenac and ibuprofen, both commonly used painkillers, increased risk of cardiac arrest significantly. Doctors recommended that consuming these painkillers should be avoided in people with existing cardiovascular disease or those with risk of developing one.

The researchers cautioned that allowing these drugs to be purchased without prescriptions, advice or restrictions, sends a message to the public that they must be safe. The findings, they said, are a stark reminder that NSAIDs are not harmless.