Panic attacks are have three inportant features:

1. They are accompanied by intense fear and anxiety
2. They usually come on fairly suddenly
3. The most intense feelings last a relatively brief time

Panic is usually accompanied by a sense that something awful is going to happen and sufferers believe they will go mad, have a heart attack, die, lose control and make a fool of themselves, amongst other fears. 

Panic attacks appear to come 'out of the blue' causing people to feel completely powerless and overwhelmed. Panic attacks can often have a significant impact on an individual’s life, leading them to avoid situations. 

Panic attacks are very common and are not a sign of serious mental illness as some people fear.