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.