Post-traumatic stress disorder is an anxiety disorder which develops after experiencing an exceptionally threatening or catastrophic event, e.g. natural disaster, serious accident, witnessing violent death of others, or being a victim of violent crime. The major symptoms are intrusive memory of the traumatic event, avoidance of situations that are reminders of the trauma, and hyper-arousal symptoms such as being easily startled and difficulty in sleeping. There are effective medication and psychological treatment for PTSD, and most patients will recover after treatment.

You can refer to the following website.

What is Post-traumatic Stress Disorder?

The source of information is provided by the Hospital Authority Castle Peak Hospital