Panic attacks are sudden, discrete periods of intense anxiety, mounting physiological arousal, fear and discomfort that are associated with a variety of somatic and cognitive symptoms. The onset of these episodes is typically abrupt, and may have no obvious triggers. Although these episodes may appear random, they are a subset of an evolutionary response commonly referred to as fight or flight that occur out of context, flooding the body with hormones (particularly epinephrine (adrenaline)) that aid in defending itself from harm. Bourne, E. (2005). The Anxiety and Phobia Workbook, 4th Edition: New Harbinger Press. Experiencing a panic attack is said to be one of the most intensely frightening, upsetting and uncomfortable experiences of a person's life. (Bourne 2005).

According to the American Psychological Association the symptoms of a panic attack commonly last approximately ten minutes. However, panic attacks can be as short as 1-5 minutes, while sometimes panic attacks may form a cyclic series of episodes, lasting for an extended period, sometimes hours. Often those afflicted will experience significant anticipatory anxiety and limited symptom attacks in between attacks, in situations where attacks have previously occurred, and in situations where they feel "trapped". That is, where escape would be obvious and/or embarrassing.

Panic attacks also affect people differently. Experienced sufferers may be able to completely "ride out" a panic attack with little to no obvious symptoms or external manifestations. Others, notably first-time sufferers, may even call for emergency services; many who experience a panic attack for the first time fear they are having a heart attack or a nervous breakdown.