This course tackles one of the most challenging realities in perioperative care: caring for surgical patients with substance use disorders. You’ll review how alcohol, opioids, stimulants, sedatives, and club drugs alter physiology, drug responses, and perioperative risk—and learn how to adjust your anesthetic plan accordingly. Practical strategies include multimodal and opioid-sparing analgesia, management of patients on methadone or buprenorphine, prevention and treatment of alcohol withdrawal, and the evidence-based use of adjuvants like gabapentinoids, ketamine, and benzodiazepines to keep complex, substance-using patients safe and comfortable throughout the perioperative course.