PTSD
Symptoms of PTSD fall into three main categories:
1. Repeated "reliving" of the event, which disturbs day-to-day activity
2. Avoidance
3. Arousal
You also might feel a sense of guilt about the event (including "survivor guilt"), and the following symptoms, which are typical of anxiety, stress, and tension:
There are no tests that can be done to diagnose PTSD. The diagnosis is made based on a certain set of symptoms that continue after you've had extreme trauma. Your doctor will do psychiatric and physical exams to rule out other illnesses.
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Ipser JC, Carey P, Dhansay Y, Fakier N, Seedat S, Stein DJ. Pharmacotherapy augmentation strategies in treatment-resistant anxiety disorders. Cochrane Syst Rev. 2006;4:CD005473.