Many medications are prescribed and administered PRN (pro re nata, as needed). However, there are few integrative reviews to inform PRN psychotropic medication use in long-term care facilities and nursing or care homes. Accordingly, this integrative systematic review aimed to improve our understanding of PRN medicines management with a focus on psychotropic medications (antipsychotics, sedatives, anxiolytics, and hypnotics) in long-term care settings. Keywords relating to PRN in English, Norwegian, and Spanish were used, and articles published between 2009 and 2019 were retrieved. Based on the inclusion criteria, eight articles were used for data analysis and synthesis. This review offers a description of PRN prescription and administration of psychotropic medications in long-term care. Variations were observed in the management of PRN psychotropic medications based on residents’ underlying health conditions and needs, duration of use, and changes between medications and doses. Neither the reasons for PRN prescription and administration nor the steps taken to identify and manage any associated adverse reactions or adverse drug events were reported. Further initiatives are needed to improve PRN medicines management to explore factors that affect PRN prescription and administration and to develop appropriate PRN guidelines to prevent harm and improve the safety of people living in long-term care facilities.