Panic attacks are very sudden and discrete periods of intense anxiety, arousal, fear, stomach problems and discomfort. These episodes are typically abrupt, lasting for about an average of 30 minutes and may have no obvious triggers. People who experience panic attacks for the first time fear that they are having a heart attack due to the similarity of symptoms. Avoidance of triggers is an essential in limiting the number of panic attacks. If in doubt, always call 911.