Dual diagnosis involves the co-occurrence of severe mental illness and substance misuse. Recent guidance has sought to improve the initial identification of dual diagnosis and the ongoing management of patients with confirmed dual diagnoses. However, service provision between mental health teams and emergency departments (EDs) can be disjointed, resulting in suboptimal care.

This article explores the care of patients who present at EDs with symptoms arising from a combination of severe mental illness and substance misuse. The author aims to alter the approach of multidisciplinary teams by applying change management theory, resulting in patients being treated by multiple healthcare disciplines in a more coordinated way. This will be demonstrated through a case study that follows a patient with dual diagnosis on the journey through an emergency department. Guidelines identifying best practice will be referred to and care failings in the patient’s journey will be analysed. The author also provides an overview of how change management theory can be used to implement a new protocol for managing the treatment of patients with a dual diagnosis.