Adult subjects will be screened in the Emergency Department (ED) by research associates. If they meet inclusion/exclusion criteria they will be offered enrollment. Subjects who choose to enroll will be randomized to receive either hydrocortisone 120mg PO, or placebo PO, one time in the Emergency Department. They will be given a packet of general information on traumatic stress and contact information for psychiatric assistance if they require it, but no further PTSD treatment will be given. Any further medical treatment will be at the discretion of the treating team.