Researchers have warned that patients could choose to stop taking medication because confusing information on possible side effects is leading them to overestimate the associated dangers.

A study of patients using Cancer Research UK’s patient information website Cancer Help UK, published in the British Journal of Health Psychology, found that patients are consistently misinterpreting information on the potential side effects of medicines.

Researchers from the University of Leeds asked participants visiting the site to estimate the risk of two side effects occurring from the chemotherapy drug Taxol or the risk of experiencing three when taking the painkiller ibuprofen.

They found that, in both cases, the risk was significantly overstated if the relevant information was provided as a ‘verbal description’ - uncommon or common, for example - or as a percentage. But when described as a frequency, ie one in 10 people, the estimation of risk was more accurate, the researchers said.

The findings are important as the risk of side effects is a huge influencing factor in patient decisions on medication and overestimation of these could mean treatment is refused unnecessarily, and the researchers hope they will help health workers and pharmaceutical companies to explain information to patients in the best possible way to avoid such a scenario.

Confusing and dangerous
“Giving information about medication in a confusing way could be dangerous. We need to explain risk in a way patients can relate to,” stressed study author Dr Peter Knapp. “For most people it is better to say ‘three in 10 people will have side effects’ rather than ‘30 per cent’ [as] percentages are abstract concepts that some people will not understand”, he explained.

And according to Liz Woolf, head of CancerHelp UK, most people think side effects from drugs are more common than they are, and this study confirms the importance of giving information to people in a way they will understand it.