Length of time varies. According to our diagnostic manual, one must have symptoms for at least one month following an event to receive a PTSD diagnosis. In some cases, particularly where it is not treated, PTSD can last a very long time, perhaps the remainder of one’s life...
Most people with longstanding PTSD find that the symptoms are not steady in their severity. For some people, the symptoms gradually fade over time. Other people find that symptoms may increase when they encounter reminders of their traumatic events. Anniversaries of the event, for example, are commonly difficult times.
John H. Krystal, M.D.
Scientific Council Member
Chair, Department of Psychiatry, Yale University