Psychiatric emergencies and crises are unforseeable by nature and can have devastating consequences. They can arise both in the course of chronic mental illness and in people who had not shown any previous signs of mental illness. Conditions that are so similar that they might be confused with one another can be caused by a wide range of internal illnesses, adverse side-effects of medications or intoxication. This is the reason why establishing a psychiatric diagnosis in emergency situations must be primarily driven by the question as to whether the differential diagnosis is an internal illness or rather intoxication. The most prevalent psychiatric emergencies in clinical practice are nervous breakdowns, psychomotor agitation and violence, suicidal tendencies, delirium, psychoses as well as addictions.