Adequacy of Patient Information on Adverse EffectsAn Assessment of Patient Information Leaflets in the UK

Background: One of the most important categories of information that patients want to know about the drug they are taking is the likelihood or probability of adverse effects. All patients should receive such information in the patient information leaflet that is supplied with all drugs. Anecdotal evidence suggests that most leaflets give little indication of the likelihood of adverse effects. The UK Medicines and Healthcare products Regulatory Agency (MHRA) suggests using a combination of words and numbers to convey this information. However, an EU guideline suggests using five verbal descriptors on a scale from common to rare, the use of which has been shown to lead to gross overestimation of the risk of adverse effects.