A high level of adrenalin is not in itself a bad thing. It can give you the extra energy to deal with difficult demands and challenges. The damage is done when the levels of adrenalin don't fall, naturally, after a stressful event. Stress becomes prolonged and tension becomes a habit.

For many people, their first panic attack comes out of the blue and creates a state of arousal. You may find yourself becoming more nervous, impatient and irritable as you feel, understandably, apprehensive about having another attack.

If you experience panic attacks over a period of time, you may develop a fear of fear. Because you have become hyper-aware of the sensations associated with fear, sensitised to them, you tense up whenever anything at all reminds you of the original panic. This can include your own bodily sensations. So someone feeling hot, or with sweaty hands (perhaps because they are in a meeting in a warm room), may assume, automatically, that they are in for another panic attack. Anticipating this makes them tense up and produces the very panic response they feared.

Agoraphobia and similar problems
You may start to associate particular places and situations with having an attack. In an attempt to avoid another one, you may steer clear of places where attacks have previously occurred. But this may put more and more restrictions on your day-to-day activities, and could lead to agoraphobia or social phobia.
Depression
As you feel more out of control and restrict your activities, your enjoyment of life and your self-confidence is undermined. Many people who experience panic attacks become very depressed.