A panic attack occurs when your body experiences a rush of intense psychological (mental) and physical symptoms. You may experience an overwhelming sense of fear, apprehension and anxiety. As well as these feelings, you may also have physical symptoms such as: nausea sweating trembling a sensation that your heart is beating irregularly (palpitations) The number of panic attacks you have will depend on how severe your condition is. Some people may have one or two attacks each month, while others may have several attacks a week.