Background People with dementia (PWD) are at risk for medication related harm due to their impaired cognition and frequently being prescribed many medications. Few previous studies of PWD inpatients have been focused on medication safety interventions.This study aimed to evaluate an intervention designed to improve medication safety for people with dementia (PWD) and their carers during an unplanned admission to hospital. This article reports the effect of the intervention on potentially inappropriate medications (PIMs), polypharmacy and anticholinergic burden scores for PWD in the study. Methods A quasi-experimental pre-post design using an intervention site and a control site was conducted in 2017-2019, in a regional area in New South Wales, Australia. PIMs, polypharmacy and anticholinergic burden were measured at admission, discharge and three months after discharge. In addition, medication reconciliation at admission and scoring of pharmacists recommendations using severity and relevance scores were measured. Results There were 628 participants including 350 in the post-intervention phase. Polypharmacy for these admissions was high, and there was approximately 30% reduction in the number of medications at discharge. PIMs at admission were also high, and decreased significantly at discharge however there was no treatment effect associated with the intervention. The mean anticholinergic burden score also decreased significantly between admission and discharge, however, no treatment effect was seen. Conclusions High rates of polypharmacy and PIMs in this study indicate this study population was admitted with multiple comorbidities. Reduced PIMs at discharge were correlated with reduced anticholinergic burden. Medication reconciliation resulted in many recommendations that contributed to the reductions in medications. Although the study did not report a treatment effect, reductions in the number of medications and PIMs reduced medication related risk for PWD. Reduced risks associated with inappropriate or unnecessary medications can reduce hospital admissions and adverse events for PWD. This intervention was feasible to implement, and future multisite studies should be designed to recruit larger study samples to evaluate interventions for improving medication safety for PWD. They should also adopt routine screening for cognitive impairment to identify PWD at admission.