A major Europe-wide change in the labelling of medicines is under way after Scottish researchers exposed how high salt levels in some products are putting patients at increased risk of strokes and heart attacks.

Research at the University of Dundee found that millions of patients were exceeding the recommended daily limits for sodium from their medicines alone, due to the inclusion of baking soda in fizzy tablets.

Lead academic on the 2013 study, Dr Jacob George from the University's School of Medicine, said that high salt levels in common medicines could put patients at increased risk of cardiovascular events such as blocked veins, and non-fatal heart attacks and strokes.

Sodium bicarbonate, a salt, is added to many commonly prescribed medicines, especially those which are soluble or effervescent, to improve their absorption into the body, but excess salt is damaging to heart health.

Researchers in Dundee working with colleagues at University College London found that patients who took common versions of drugs containing sodium had a 16% greater risk of heart attack, stroke or vascular death compared with patients taking variants drugs which were identical but for the fact that they lacked sodium.

As a result of their work, which examined patients over a 23 year period between 1987 and 2010, the researchers called for the public to be warned about the potential risks of high sodium levels in prescription medicines and said medics should prescribe formulations containing sodium with caution after assessing whether the benefits outweigh the risks. They also called for medicines to be labelled in the same way as foods, to make clear the salt levels they contain.

Now the European Medicines Agency has taken action on the basis of their evidence, recommending a continent-wide change in labelling of all medicines manufactured, sold, distributed and consumed in Europe.

Dr George said, “We are delighted that our research has had this impact and has led to the EMA to recommend this action. It is vital that the public are given the correct information about the medicine they are taking to ensure it does not lead to more serious health complications.

“Prescription of these sodium-containing formulations should be done with caution, and patients prescribed them should be closely monitored for the emergence of hypertension and heart problems. Taking the maximum daily dose of some medicines can significantly increase the chances of cardiovascular events so this is a matter of public health importance and we felt it was vitally important for salt content of medicines to be labelled in same way as foods.”

In carrying out their research, Dr George’s team took into account other factors likely to affect the results, including weight, smoking and drinking and a patient's history of any chronic illnesses.

Patients with high blood pressure in particular were a concern as researchers found they are seven times more likely to be prescribed high salt medicines. Death rates were 28 per cent higher in this group, largely through increased risk of stroke and high blood pressure.