In the acute aftermath of exposure to extreme stress, nearly all trauma survivors experience one or more transient symptoms of stress. In the short run, these symptoms may serve an adaptive role and generally remit; in some cases, however, acute stress-related symptoms do not diminish and instead evolve into posttraumatic stress disorder (PTSD). At present it is not clear when and with whom to intervene. On one hand, it is possible that some responses, such as early intrusive memories, effectively recruit support from others and facilitate the psychological processing of trauma; on the other hand, failing to intervene clinically with a recently traumatized individual may permit the subsequent development of PTSD. In this review, we focus on potential pharmacologic interventions aimed at treating early symptoms of extreme arousal or dissociation with the hope of possibly preventing PTSD. To date there is almost no empirical data on effective pharmacologic interventions in the immediate aftermath of extreme psychological trauma. As a result, much of what is discussed in this review is speculative in nature