How does the side‐effect information in patient information leaflets influence peoples’ side‐effect expectations? A cross‐sectional national survey of 18‐ to 65‐year‐olds in England

OBJECTIVES To establish how the terms recommended by the European Commission to describe side-effect risk in patient information leaflets (PILs) influences expectations of side-effects and to identify factors associated with these side-effect expectations. DESIGN A cross-sectional online survey was carried out by a market research company. SETTING Data were collected in England between 18th March and 1st April 2016. PARTICIPANTS A total of 1003 adults aged between 18 and 65. MAIN OUTCOME MEASURES Self-reported expectation that the described side-effects would affect participants if they took the medicine, measured on a likelihood scale from 1 (very unlikely) to 5 (very likely). RESULTS Participants formed high expectations of side-effects for "very common" and "common" side-effects, with 51.9% and 45.0% of participants rating these as "very likely" or "likely" to happen to them, respectively. This fell to 8.1% for "uncommon," 5.8% for "rare" and 4.1% for "very rare." For each descriptor, higher expectations of side-effects were more associated with women or being from an ethnic minority, or having less education, a household illness, high perceived sensitivity to medicines or negative beliefs about medicines. DISCUSSION The current use of verbal descriptors to communicate side-effect risk in PILs leads to high side-effect expectations. These expectations could contribute to nocebo-induced medication side-effects experienced by patients. Additional work is required to identify ways to improve the way risk information is conveyed in PILs.