Inclusion Criteria:  Age ≥ 18 years Weight: 99 lb - 242 lbs Experienced a traumatic event less than 6 hours ago  Secondary Inclusion Criteria:  ED staff note marked anxiety emotional distress and or dissociation in relation to index trauma as assessed by meeting a minimum of 2 out of 4 of the peritraumatic characteristics that have been associated with the development of PTSD below:  Anxiety Visual Analog Scale minimum score of 4 on a scale of 0 to 10 Peritraumatic dissociation (PDEQ) with a cut-point of 15 (lowest possible score is 10) Peritraumatic distress (Peritraumatic Distress Inventory) (PDI) with a cut-point of 15 (lowest possible score is 0) Heart rate at 80 bpm or more  Exclusion Criteria:  Severe physical injury as assessed with the Abbreviated Injury Scale (AIS > 2); Examples include severe burn injury, life-threatening medical or surgical condition, condition requiring surgical intervention under general anesthesia, as indicated by clinical judgment. Inability to provide informed consent or cooperate with the screening or collection of initial measures. Intoxication to a degree that would interfere with the ability to provide informed consent or high level or intoxication reported at the time of trauma. Moderate to severe head injury associated with current trauma exposure as defined by a loss of consciousness >30 minutes following injury. Medical conditions e.g., Cushing's syndrome, current acute infectious or viral disease, tuberculosis, unstable diabetes or hypertension, myasthenia gravis, heart failure. Currently taking oral steroids Use of benzodiazepine within 24 hours of trauma exposure will not be eligible to participate in the study Individuals prescribed a narcotic medication to alleviate acute pain in the ED will not be eligible to participate in the treatment study. Weight below 45kg or above 110 kg (99 lbs - 242 lbs) Pregnancy (a urine pregnancy test will be performed in the ED) Individuals experiencing on-going trauma (i.e., domestic violence). Reported diagnoses of schizophrenia, bipolar I disorder, or other psychotic illness. Current or past history of dementia, amnesia or other cognitive disorder predating trauma exposure Residence outside local area, which would hinder attendance at follow up visits due to long travel time.