The range and extent of inhaled corticosteroid (ICS) side effects experienced by patients in the general community are likely to be underestimated. AIMS: To identify the side effects of ICS perceived by patients in the community and, through the use of a self-report questionnaire, measure their intensity, prevalence and relationship with daily medication dose. METHODS: Focus groups and in-depth interviews were conducted to identify side effects that patients associated with their use of ICS. In an international multicentre cross-sectional survey, 395 inhaler users from community pharmacy (mean age 50, 53% female), divided into 4 daily dosage groups (beta2-agonist without ICS n=66, beclometasone dipropionate (BDP) equivalent ICS low dose 400 microg, n=109; mid dose 401-800 microg, n=151; and high dose>800 microg, n=69) reported how much they were affected by these side effects on a 7-point Likert scale. RESULTS: Focus groups and interviews revealed 57 side effects that were associated with ICS use. Cross-sectional survey results showed significant differences in side effect perception between the four dosage groups for 31 items (all P0.01) and a rising intensity with increasing ICS dose for total side effect score (P<0.001). For ICS users reporting the most bothersome side effects (scoring 3 on 0-6 scale) there was a rising prevalence as ICS dose increased for 34 items. A multivariate model confirmed that mid and high ICS dosages were statistically significantly associated with side effect perception after controlling for the other factors and covariates. CONCLUSIONS: Higher daily ICS doses were associated with a higher intensity and a higher prevalence of many patient perceived side effects, lending support to the call for dose titration in clinical practice. Results indicate the usefulness of patient self-report scales for understanding the burden of side effects of ICS in the community.