This book fills a gap in the existing medical literature by providing a best-practice approach to the evaluation and acute treatment of patients presenting for emergency care with identifiable substance use and/or co-occurring psychiatric disorders. As the first interdisciplinary book to integrate psychiatric and emergency care, the text uniquely covers a myriad of serious medical conditions, acute mental status and dangerous behavioral abnormalities. The book focuses on guidelines that support emergency room physicians with little formal medical training in addiction medicine. The first section focuses on the diagnosis and management of substance-specific intoxication and withdrawal states, as well as common medical co-morbidities and disposition considerations. The book lends particular attention to the identification and stabilization of high risk medical conditions associated with each substance of abuse.  The second section is psychiatrically focused, addressing the most common psychiatric symptoms and syndromes, their association with SUDs, an approach to differential diagnosis, and discussion of crucial treatment considerations for both safe ED management and post-ED disposition.  A final section includes other pertinent topics, for example, the assessment of patient safety, responding to the medication-seeking patient, assessment and treatment of pregnant patients and working with adolescents and their families around substance use.Substance Use and The Acute Patient is a unique and valuable contribution to the literature for both consulting psychiatrists, emergency medicine specialists, addiction medicine specialists, and all other medical professionals who provide care for these most complex and underserved patients.