Objectives: We sought to review studies that examine healthcare professionals' and students' knowledge, attitudes, and practices (KAP) regarding medication disposal. We also explore recommendations and barriers related to appropriate medication disposal. Design: A systematic review was conducted that adhered to Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA). Data sources: MEDLINE, Embase, CINAHL, Web of Science, PsycINFO and Google Scholar were searched up to 23rd February 2024. Study eligibility criteria and setting: Qualitative, quantitative, and mixed-method primary research studies. There was no limitation on the publication date, geographical locations, or the study settings. Participants: Pharmacists, doctors, nurses, and students from these respective professional groups in any country. Primary outcome measures: The levels of healthcare staff and students' knowledge, attitudes, and practices about disposal of unwanted medications. Date extraction and synthesis: Data extraction was conducted by four of the researchers independently. The study details were categorised into three main domains, i.e., knowledge, attitude, and practice using the KAP model. Other relevant information was also extracted, and synthesised in overall themes, such as challenges and recommendations. Results: 37 studies from 18 countries (Asia n=21; USA n=7; Africa n=5; and EU n=2; South America n=2) were included. 86.5% (n=32) investigated participants' knowledge of medication disposal. Although there was a good level of awareness about the environmental impacts, there were significant gaps in knowledge regarding correct disposal methods, available services, guidelines, and training. 30 studies explored participants' attitudes toward medication disposal. There was a generally positive attitude towards the need for environmentally safe disposal practices. 35 studies evaluated participants' practices in relation to medication disposal. Although there was generally a positive attitude and some understanding of appropriate disposal methods, the majority of the participants did not follow the practice guidelines, especially outside healthcare settings. Discussions and Conclusions: While healthcare staff and students have fair knowledge and positive attitudes toward medicine disposal, their actual practices are lacking. One significant challenge identified is the limited awareness about proper disposal methods coupled with a lack of established services or guidelines. Even in cases where take-back programs are available, they often face issues with accessibility. To tackle these challenges, it is suggested that governmental bodies should establish and enforce clear policies on medication disposal while also expanding educational initiatives to increase understanding among professionals and students. Furthermore, improving access to take-back programs is crucial for ensuring safe medication disposal and minimising potential environmental and health hazards. PROSPERO registration number: CRD42024503162.
