Ketamine is a well-described anesthetic and analgesic, unique in its ability to preserve laryngeal reflexes and airway protection, and offered to a wide range of patients, although not necessarily widely used. Because it is considered an anesthetic, widespread use by all sedation providers is often limited despite its long history as a safe sedative. Because of its sympathomimetic effects, ketamine may be used in patients who are hypovolemic, including those who are experiencing traumatic or obstetric emergencies. The use of ketamine in patients with epilepsy or traumatic brain injury is more controversial. This article will explore the side effects of ketamine and current research that support or discourage its use in a variety of settings.