BACKGROUND: Involuntary treatment for individuals who lack sufficient capacity to make informed decisions regarding treatment has been associated with increased rates of injectable antipsychotics, antipsychotic polytherapy, and/or high doses. However, little is known about non-antipsychotic psychotropic prescription, or psychotropic medication burden as a more encompassing approach for people treated involuntarily. The aim of this study was to examine the relationship between Mental Health Act (MHA) status and psychotropic polypharmacy and/or high-dose medication prescribing practices in an Australian inpatient mental health unit. METHODS: A retrospective cohort study of 800 adults discharged from a large metropolitan Queensland mental health unit was undertaken. Data was collected for 200 individuals, discharged on at least one psychotropic medicine, at four time periods; Cohort 1 (on or before 31st January 2014), Cohort 2 (2015), Cohort 3 (2016) and Cohort 4 (2017). The number of prescribed medicines and total daily doses were recorded and reviewed for alignment with current clinical guidelines. Participant demographics and clinical characteristics were compared by individual MHA status using chi-square test for categorical variables and analysis of variance for continuous variables. Associations between MHA status and prescribing practices (psychotropic polypharmacy and/or high-dose prescribing) were assessed using bivariate and multivariate binomial logistic regression models. Age, gender, birth country, year of admission, admissions in previous 12 months, primary diagnosis, ECT/clozapine treatment, and other psychotropic medications were adjusted as covariates. RESULTS: Regression analysis found that compared to their voluntary counterparts, individuals treated involuntarily were 2.7 times more likely to be prescribed an antipsychotic at discharge, 8.8 times more likely to be prescribed more than one antipsychotic at discharge and 1.65 times more likely to be prescribed high-dose antipsychotic treatment at discharge. The adjusted model also found that they were half as likely to be prescribed an antidepressant at discharge. CONCLUSION: Implicit review of justifications for increased psychotropic medication burden (antipsychotic polypharmacy and high-doses) in those treated involuntarily is required to ensure clinical outcomes and overall quality of life are improved in this vulnerable group. Clearly documented medication histories, reconciliation at discharge and directions for medication management after discharge are necessary to ensure quality use of medicines.