Post-traumatic stress disorder (PTSD) is an anxiety disorder that can develop after exposure to a traumatic event involving threat of harm or death. Symptoms include reliving the event through flashbacks or nightmares, avoiding reminders of the trauma, feeling numb or on edge. Cognitive behavioral therapy and exposure therapy can help reduce fear and change distressing thoughts related to traumatic memories. Medications like SSRIs are also used to target PTSD symptoms.