Unclear information is the reason patients are overestimating the side effects of medicines, reveals a new survey.
The finding attains significance because if the possible side effects of medicines are unclear, or patients cannot understand how common they are, there is a risk they will not take drugs prescribed for them.
Published in the British Journal of Health Psychology, the study has shown that people overestimate the risk of suffering a side effect by up to 50 per cent, if the information leaflet is unclear.
This, according to the study report, can influence patients' decisions about whether or not to take prescribed medication.
During the survey, 285 visitors to Cancer Research UK's patient information website, CancerHelp, were questioned.
It was found that using percentages, as in '20 per cent of patients will suffer a side effect', or using words, such as common and uncommon, lead people to interpret the likelihood of suffering a side effect differently.
The survey revealed that the risks were much clearer if expressed as a 'one in' chance, such as one in five people will suffer a side effect.
"These are important findings which will help health workers and pharmaceutical companies explain information to patients in the best possible way," the Telegraph quoted Dr. Peter Knapp, study author based at the University of Leeds, as saying.
"Giving information about medication in a confusing way could be dangerous.
"We need to explain risk in a way patients can relate to. For most people it is better to say 'three in 10 people will have side effects' rather than '30 per cent'.
"Percentages are abstract concepts that some people will not understand. The use of percentages means that some people will misinterpret information or ignore it. Both could lead to them making an uninformed decision not to take a medicine," he added.
Liz Woolf, head of CancerHelp UK, said: "This study confirms what we know from producing content for CancerHelp UK, that you have to make sure you give information to people in a way they will understand it. Most people think side effects from drugs are much more common than they actually are. The study confirms that natural frequency - one in five - is the clearest way to express this type of information so that the majority will understand it clearly."