A Panic Attack is defined as an episode of intense fear of sudden onset, usually peaking within a minute.  The fear, often bordering on terror, is generally accompanied by unpleasant bodily sensations, difficulty in reasoning, and a feeling of imminent catastrophe which can be expressed as: “Something terrible is happening to me”; “I am in great danger”.

Experiencing a panic attack is said to be one of the most intensely frightening, upsetting and uncomfortable experiences of a person's life. According to the American Psychological Association the symptoms of a panic attack commonly last approximately thirty minutes. However, panic attacks can be as short as 15 seconds, 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.  

Some panics are unexpected; it feels as if they ‘come out of nowhere’. Others are regularly provoked by exposure to identifiable stresses, and therefore can be anticipated.  Whether spontaneous or predicable, panics are very upsetting.

Panic attacks are commonly linked to agoraphobia and the fear of not being able to escape a bad situation. Many who experience panic attacks feel trapped and unable to free themselves.
The effects of a panic attack vary from person to person. Some, notably first-time sufferers, may call for emergency services. Many, who experience a panic attack, mostly for the first time, fear they are having a heart attack or a nervous breakdown.

Descriptions:
Sufferers of panic attacks often report a fear or sense of dying, "going crazy", or experiencing a heart attack or "flashing vision", feeling faint or nauseated, heavy breathing, or losing control of themselves. These feelings may provoke a strong urge to escape or flee the place where the attack began (a consequence of the sympathetic "fight or flight" response).

A panic attack is a response of the sympathetic nervous system (SNS). The most common symptoms may include trembling, dyspnea (shortness of breath), heart palpitations, chest pain (or chest tightness), hot flashes, cold flashes, burning sensations (particularly in the facial or neck area), sweating, nausea, dizziness (or slight vertigo), light-headedness, hyperventilation, paresthesias (tingling sensations), sensations of choking or smothering, and derealization. These physical symptoms are interpreted with alarm in people prone to panic attacks. This results in increased anxiety, and forms a positive feedback loop.

Often the onset of shortness of breath and chest pain are the predominant symptoms, the sufferer incorrectly appraises this as a sign or symptom of a heart attack. This can result in the person experiencing a panic attack seeking treatment in an emergency room.

Panic attacks are distinguished from other forms of anxiety by their intensity and their sudden, episodic nature. They are often experienced in conjunction with anxiety disorders and other psychological conditions, although panic attacks are not always indicative of a mental disorder.

• Long-term, predisposing causes — Heredity. Panic disorder has been found to run in families, and this may mean that inheritance plays a strong role in determining who will get it. However, many people who have no family history of the disorder develop it. Various twin studies where one identical twin has an anxiety disorder have reported an incidence ranging from 31 to 88 percent of the other twin also having an anxiety disorder diagnosis. Environmental factors such as an overly cautious view of the world expressed by parents and cumulative stress over time have been found to be causes.

• Biological causes — obsessive compulsive disorder, post traumatic stress disorder, hypoglycemia, hyperthyroidism, Wilson's disease, mitral valve prolapse, pheochromocytoma and inner ear disturbances (labyrinthitis). Vitamin B deficiency from inadequate diet or caused by periodic depletion due to parasitic infection from tapeworm can be a trigger of anxiety attacks.

• Phobias — People will often experience panic attacks as a direct result of exposure to a phobic object or situation.

• Short-term triggering causes — Significant personal loss, including an emotional attachment to a romantic partner, life transitions, significant life change, stimulants such as caffeine or nicotine, or the drugs marijuana or psilocybin, can act as triggers.

• Maintaining causes — Avoidance of panic provoking situations or environments, anxious/negative self-talk ("what-if" thinking), mistaken beliefs ("these symptoms are harmful and/or dangerous"), withheld feelings, lack of assertiveness.

• Lack of assertiveness — A growing body of evidence supports the idea that those that suffer from panic attacks engage in a passive style of communication or interactions with others. This communication style, while polite and respectful, is also characteristically un-assertive. This un-assertive way of communicating seems to contribute to panic attacks while being consistently present in those that are afflicted with panic attacks.

• Medications — Sometimes panic attacks may be a listed side effect of medications such as Ritalin (methylphenidate) or even fluoroquinolone type antibiotics. These may be a temporary side effect, only occurring when a patient first starts a medication, or could continue occurring even after the patient is accustomed to the drug, which likely would warrant a medication change in either dosage, or type of drug. Nearly the entire SSRI class of antidepressants can cause increased anxiety in the beginning of use. It is not uncommon for inexperienced users to have panic attacks while weaning on or off the medication, especially ones prone to anxiety.

• Alcohol, medication or drug withdrawal — Various substances both prescribed and unprescribed can cause panic attacks to develop as part of their withdrawal syndrome or rebound effect. Alcohol withdrawal and benzodiazepine withdrawal are the most well known to cause these effects as a rebound withdrawal symptom of their tranquillising properties.

• Hyperventilation syndrome — Breathing from the chest may cause overbreathing, exhaling excess carbon dioxide in relation to the amount of oxygen in one's bloodstream. Hyperventilation syndrome can cause respiratory alkalosis and hypocapnia. This syndrome often involves prominent mouth breathing as well. This causes a cluster of symptoms including rapid heart beat, dizziness, and lightheadedness which can trigger panic attacks.

• Situationally bound panic attacks — Associating certain situations with panic attacks, due to experiencing one in that particular situation, can create a cognitive or behaviorally predisposition to having panic attacks in certain situations (situationally bound panic attacks). It is a form of classical conditioning.

• Pharmacological triggers — Certain chemical substances, mainly stimulants but also certain depressants, can either contribute pharmacologically to a constellation of provocations, and thus trigger a panic attack or even a panic disorder, or directly induce one. This includes caffeine, amphetamine, alcohol and many more. Some sufferers of panic attacks also report phobias of specific drugs or chemicals, that thus have a merely psychosomatic effect, thereby functioning as drug-triggers by non-pharmacological means.

• Chronic and/or serious illness — Cardiac conditions that can cause Sudden Death such as Long QT syndrome; CPVT or Wolff-Parkinson-White syndrome can also result in panic attacks. This is particularly difficult to manage as the anxiety relates to events that may occur such as cardiac arrest, or if an Implantable cardioverter-defibrillator is in situ, the possibility of having a shock delivered. It can be difficult for someone with a cardiac condition to distinguish between symptoms of cardiac dysfunction and symptoms of anxiety. In CPVT, anxiety itself can and does trigger arrythmia.Current management of panic attacks secondary to cardiac conditions appears to rely heavily on Benzodiazepines; Selective serotonin reuptake inhibitors and/or Cognitive Behavioural Therapy. Although often this group of people experience multiple and unavoidable hospitalisations as without an electrocardiogram it can be difficult to differentiate between symptoms of panic attack and cardiac symptoms in those with these types of diagnosis.

While the various symptoms of a panic attack may feel that the body is failing, it is in fact protecting itself from harm. The various symptoms of a panic attack can be understood as follows. First, there is frequently (but not always) the sudden onset of fear with little provoking stimulus. This leads to a release of adrenaline (epinephrine) which brings about the so-called fight-or-flight response wherein the person's body prepares for strenuous physical activity. This leads to an increased heart rate (tachycardia), rapid breathing (hyperventilation) which may be perceived as shortness of breath (dyspnea), and sweating (which increases grip and aids heat loss). Because strenuous activity rarely ensues, the hyperventilation leads to a drop in carbon dioxide levels in the lungs and then in the blood. This leads to shifts in blood pH (respiratory alkalosis or hypocapnia), which in turn can lead to many other symptoms, such as tingling or numbness, dizziness, burning and lightheadedness. Moreover, the release of adrenaline during a panic attack causes vasoconstriction resulting in slightly less blood flow to the head which causes dizziness and lightheadedness. A panic attack can cause blood sugar to be drawn away from the brain and towards the major muscles. It is also possible for the person experiencing such an attack to feel as though they are unable to catch their breath, and they begin to take deeper breaths, which also acts to decrease carbon dioxide levels in the blood.

DSM-IV Diagnostic Criteria for Panic Attack

A discrete period of intense fear or discomfort, in which four (or more) of the following symptoms developed abruptly and reached a peak within 10 minutes:

• palpitations, pounding heart, or accelerated heart rate
• sweating
• trembling or shaking
• sensations of shortness of breath or smothering
• feeling of choking
• chest pain or discomfort
• nausea or abdominal distress
• feeling dizzy, unsteady, lightheaded, or faint
• derealization (feelings of unreality) or depersonalization (being detached from oneself)
• fear of losing control or going crazy
• fear of dying
• paresthesias (numbness or tingling sensations)
• chills or hot flashes