 Welcome to Part 1 for the Agitated Patient. In this section, we'll discuss the causes for acute agitation in the emergency department. In main categories, the causes can be psychiatric or medical. For psychiatric reason, they can be from mood disorders such as depression or bipolar disorder. It can also be from thought disorders such as schizophrenia. They can be from a previously undiagnosed disorder, non-compliance with medication, or an acute stressor. Substance abuse can cause exacerbation of existing mood or thought disorder or precipitate symptoms of a new mood or thought disorder. The following are the medical causes of acute agitation. A main one is sepsis. It can be a general infection or specifically encephalitis meningitis. Intercranial process such as trauma leading to bleeding, abscess, tumor. Endocrine causes can include thyroid toxicosis or hypoglycemia. Environmental causes can include heat stroke. Another big category is substance use. Either from using of substance or withdrawal. Substance as causes agitation can include sympathomimetics, anticholinergic, serotonin drugs, withdrawal from substance such as alcohol, and opioid can produce agitation. In summary, we discuss the medical and psychiatric causes for acute agitation. These causes will form the basis for your approach when you see a patient like that in the emergency department.