Soluble painkillers – many of which you can buy over- the-counter without a prescription – contain so much salt that they can increase the chances of developing high blood pressure (hypertension) more than seven times. They also raise the risk of a heart attack, stroke or fatal heart failure by 20 per cent.

People who regularly take soluble medication are especially at risk, say researchers from Dundee University, apparently the first to ‘discover’ that effervescent tablets contain sodium. It is often combined with bicarbonate, a substance that makes the tablets fizz.

Levels of sodium were as high as 18mmol, which equates to one-fifth of a teaspoon, in one everyday painkiller. As the daily safe consumption of sodium is 104mmol, someone taking eight painkillers a day would exceed the limit by around 44mmol.

The researchers tested a range of painkillers, including paracetamol and aspirin.

(Source: British Medical Journal, 2013; 347: f6954)