The 17 Most Common Symptoms of PTSD Vivid Flashbacks. A PTSD flashback is when you relive your traumatic experience, and it feels like it is happening all over again right in that moment. ... Nightmares. ... Self-Isolation. ... Depression. ... Substance Abuse. ... Emotional Avoidance. ... Feeling on Edge, or Hyperarousal. 1 Feb 2021