Serotonin toxicity is frequently underrecognized and underappreciated, and oftentimes confused with serotonin syndrome. In this course, time will be spent reviewing, comparing, and contrasting symptoms and diagnostic criteria for serotonin toxicity and serotonin syndrome. A general discussion describing toxicity will be broken down into three main categories: mild toxicity where there are serotonergic features that may or may not concern the patient; moderate toxicity which causes significant distress and needs treatment, but is not life-threatening; and severe toxicity which is a medical emergency.