This publication examines the case for distributing naloxone, an emergency medication, to people who inject opioids such as heroin and to others who might witness an opioid overdose. Through its capacity to reverse opioid overdose, naloxone can save lives if administered in time. This comprehensive review looks at opioid overdose and how naloxone counteracts it, and discusses the circumstances of opioid overdose deaths and the use of naloxone in regular clinical practice. As well as documenting the historical development and spread of take-home naloxone programmes in Europe and beyond, the study looks at the practical side of their implementation, including the training of naloxone recipients in how to recognise and respond to an overdose. Although take-home naloxone is supported by the World Health Organization, the report finds that barriers to its access exist in Europe and considers how the availability of the intervention may be expanded.