What are the main symptoms of anxiety?

Several: Sometimes it's normal to feel anxiety -- feeling jittery and tense before taking an exam or giving a speech, for instance. It's the body's natural response to perceived danger, and can keep you alert. If it becomes a disorder, you could feel more extensive dread, worry, sudden bouts of panic, etc. http://www.helpguide.org/mental/anxiety_types_symptoms_treatment.htm.

ANXIETY: Common symptoms are feelings of apprehensive, powerless, impending doom, panic, rapid heart rate, hyperventilation, sweating, trembling, feeling weak or tired. These are consistent with sympathetic nervous system activation that may be related to scary thoughts. Deep breathing can send a parasympathetic volley to the heart and reduce anxiety. Therapy & certain medications can help tremendously.