Introduction Nursing home residents often have a high number of comorbidities resulting in polypharmacy. Inappropriate prescribing is therefore likely to occur, which in turn is expected to worsen cognitive impairment, to increase the fall risk and to decrease residents’ quality of life. The objective of the ‘Discontinuing Inappropriate Medication in Nursing Home Residents’ (DIM-NHR) study is to examine the efficacy and cost-effectiveness of the Multidisciplinary Multistep Medication Review (3MR) that is aimed at optimising prescribing and discontinuing inappropriate medication.

Methods A cluster randomised controlled trial will be conducted. Elderly care physicians and their wards (clusters) will be randomised. Data will be collected at baseline and 4 months after the 3MR has taken place. Six hundred nursing home residents will be recruited of whom more than half are expected to suffer from dementia. The 3MR will be based on consensus criteria and the relevant literature and will be performed by the patient’s elderly care physician in collaboration with a pharmacist.

Analysis Primary outcomes—the difference in proportion of residents who successfully discontinued inappropriate medication between the intervention and control group at follow-up. Secondary outcomes—undertreatment, exposure to anticholinergic and sedative medicines, neuropsychiatric symptoms, cognitive function, falls, hospital admission, quality of life and cost-effectiveness.

Ethics and dissemination Participant burden will be kept at a minimum. The elderly care physician will remain free to adjust medication when symptoms relapse or adverse events occur, rendering serious adverse events highly unlikely. Study findings will be published in peer-reviewed journals and a 3MR toolkit will be developed.

Trial registration number This study has been registered at http://www.ClinicalTrials.gov (trial registration number: NCT01876095)