Inclusion Criteria:  ED patients Patients 18 years of age acute and chronic painful conditions pain with a score of 5 or more on a standard 11- point (0 to 10) numeric rating scale. Patients will have to be awake, alert, and oriented to person, place, and time, Be able to demonstrate understanding of the informed consent process and content. Patients also will have to demonstrate ability to verbalize the nature of any adverse effects they might experience as well as to express their pain severity by using the NRS.  Exclusion Criteria:  Altered mental status, allergy to ketamine, pregnant patients, weight greater than 150 kg, unstable vital signs (systolic blood pressure <90 or>180 mm Hg, pulse rate <50 or >150 beats/min, and respiration rate <10 or >30 breaths/min), inability to provide consent, past medical history of alcohol or drug abuse, or schizophrenia.