Many people try to limit the amount of sodium (salt) in their diet, as high levels can increase their blood pressure and possibly raise their risk of strokes and other heart and circulation problems. However, not many people realise that soluble forms of common medicines - such as paracetamol and aspirin - also contain sodium. These include bubbling ‘effervescent’ tablets as well as powders and other tablets that you dissolve in water.
The amount of sodium in these medicines can be quite high, sometimes exceeding the government’s recommended limit of 2.4 grams a day - and this is without adding in any sodium people get from what they eat and drink. Drug makers aren’t required to list how much sodium is in medicines, so it’s difficult to know how much you’re getting.
In the new study, researchers wanted to find out what effect this extra sodium might have on people’s risk of heart and circulation problems. Using a large UK health database, they gathered information on more than 1.2 million people aged 18 and older who’d been prescribed either sodium-containing soluble medicines, or the same medicines in a form without sodium (such as a capsule they swallowed). Over an average follow-up of seven years, around 61,000 people had a stroke or heart attack, or died of a heart or circulation problem. The researchers looked at whether there was a link between these problems and being prescribed soluble medicines.
People who got a serious heart or circulation problem during the study were more likely to have been prescribed soluble medicines.
The link was strongest between soluble medicines and stroke. The researchers estimated that people taking these medicines were 22 percent more likely to have a stroke, after factoring in other things that might have affected their risk, such as smoking, being overweight, or having other health issues.
This may sound like a large increase in risk, but the actual increase would be fairly small for many people. For example, if you normally had a 5 in 100 chance of having a stroke, your risk would be around 6 in 100 if you took soluble medicines. However, people taking soluble medicines were far more likely to have high blood pressure, with their risk being seven times higher than that of people taking other forms of the medicines.
How reliable is the research?
This was a very large study that gathered information from a good-quality health database. Its findings should be fairly reliable.
However, this type of study can’t prove cause and effect, so we can’t be certain that people had a higher risk of having a stroke or other problems because they took soluble medicines. It’s possible that something else increased their risk. For example, the researchers weren’t able to consider people’s family history of these problems or what they usually ate. These things could have affected the findings.
It’s also worth noting that the study looked only at prescription medicines. So we don’t know whether the findings would be the same for soluble medicines available over the counter.
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