A panic attack is a period of intense, often temporarily debilitating, sense of extreme fear or psychological distress, typically of abrupt onset. Though it is often a purely terrifying feeling to the sufferer, panic attacks are actually an evolutionary body response often known as the fight-or-flight response occurring out of context. Symptoms may include trembling, shortness of breath, heart palpitations, chest pain (or chest tightness), sweating, nausea, dizziness (or slight vertigo), light-headedness, hyperventilation, paresthesias (tingling sensations), and sensations of choking, smothering and dreamlike and disconnected sensations. During a panic attack, the body typically releases large amounts of adrenaline into the bloodstream. Many first time sufferers of a panic attack believe they are dying, going insane or having a heart attack. Many say panic attacks are among the most frightening experiences of their lives. Repeated and seemingly unprovoked panic attacks may be a sign of panic disorder, but panic attacks are associated with other anxiety disorders as well. For example, people who suffer from phobias may experience panic attacks upon exposure to certain triggers. People with panic disorder often can be successfully treated with therapy and/or anti-anxiety medication or antidepressants.
Most sufferers of panic attacks report a fear of dying, "going crazy", having a heart attack, fainting, vomiting, or losing control of emotions or behavior. These feelings generally provoke a strong urge to escape or flee the place where the attack began ("fight or flight" reaction) and, when associated with chest pain or shortness of breath frequently result in the sufferer seeking medical attention, often in an emergency room. Panic attacks have been linked to high quantities of acetylcholinesterase in the blood.[citation needed] Also the release of adreno-cortisols aid in catalyzing the panic attacks.[citation needed]

The panic attack is distinguished from other forms of anxiety by its intensity and its sudden, episodic nature. Panic attacks are often experienced by sufferers of anxiety disorders and other psychological conditions involving anxiety, though panic attacks are not always indicative of a mental disorder, nor are they uncommon. In fact, some sufferers are not under any "fear" or any psychological illness but are under extreme amounts of stress and anxiety resulting in a panic attack or an anxiety attack. Up to 10 percent of otherwise healthy people experience an isolated panic attack about once per year, and 1 in 60 people in the U.S. will suffer from a panic disorder at some point in their lifetime.

When the sufferer experiences more than four bodily symptoms at once it is said that they have had a full-blown panic attack, while experiencing four or fewer symptoms constitutes a limited symptom attack.

More severe panic attacks may form a series of episodes waxing and waning every few minutes, lasting for a period of up to two hours, only to be ended by physical exhaustion and sleep.
In conditions of chronic anxiety, one panic attack can roll into another, leading to nervous exhaustion over a period of hours or even days.

People with phobias will often experience panic attacks as a direct result of exposure to their trigger. These panic attacks are usually short-lived and self-limiting, as they will subside once the trigger is no longer present.

Hyperventilation alone can bring about some of the symptoms of a panic attack. However, the person experiencing the panic attack often does not realize this and sees these symptoms as further evidence of how serious their condition is. An ensuing positive feedback loop of adrenaline release fuels worsening physical symptoms and psychological distress.

Panic disorder has been found to run in families, and this may mean that inheritance genes plays a strong role in determining who will get it. However, many people who have no family history of the disorder develop it. Often the first attacks are triggered by physical illnesses, a major life stress, or certain medications.
Sometimes panic attacks may be a listed side effect of medications such as Ritalin (methylphenidate). It 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.

Physiological explanation
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), 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 which in turn can lead to many other symptoms, such as tingling or numbness, dizziness, burning and lightheadedness. 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.
Symptoms:

Physical
Sweating
Shortness of breath (dyspnea)
Racing or pounding heartbeat or palpitations
Chest pain
Dizziness or vertigo
Lightheadedness
Nausea / stomach pains
Hyperventilation
Choking or smothering sensations
Uncontrollable itching
Tingling or numbness in the hands, face, feet or mouth (paresthesia)
Hot/cold flashes
Faintness
Trembling or shaking
Exhaustion

Mental Loss of the ability to react logically to stimuli
Loss of cognitive ability in general
Racing thoughts (often based on fear)
Loud internal dialogue
Feeling of impending doom
Feeling of going crazy

Emotional Terror, or a sense that something unimaginably horrible is about to occur and one is powerless to prevent it
Fear that the panic is a symptom of a serious illness
Fear of losing control
Fear of death
Fear of going crazy
Flashbacks to earlier panic trigger

Perceptual
Tunnel vision
Heightened senses
The apparent slowing down or speeding up of time
Dream-like sensation or perceptual distortion (derealization)
Dissociation, or the perception that one is not connected to the body or is disconnected from space and time (depersonalization)

Mnemonic
The symptoms of a panic attack can be remembered with the mnemonic: STUDENTS FEAR the 3 Cs: Sweating, Trembling, Unsteadiness/dizziness, Derealization/depersonalization, Elevated heart rate (tachycardia), Nausea, Tingling, Shortness of breath,FEAR of dying, FEAR of losing control, FEAR of going crazy, 3 Cs - Choking, Chest pain, Chills.

Agoraphobia
People who have had a panic attack in certain situations — for example, while driving, shopping in a crowded store, or riding in an elevator — may develop irrational fears, called phobias, of these situations and begin to avoid them. Eventually, the pattern of avoidance and level of anxiety about another attack may reach the point where individuals with panic disorder are unable to drive or even step out of the house. At this stage, the person is said to have panic disorder with agoraphobia. This can be one of the most harmful side-effects of panic disorder as it can prevent sufferers from seeking treatment in the first place. Agoraphobia of this degree is extremely rare. It should be noted that upwards of 90% of agoraphobics achieve a full recovery. Agoraphobia is actually not a fear of certain places but a fear of having panic attacks in certain places, where escape would be difficult and/or embarrassing.
The thinking behind agoraphobia usually follows the line that were a panic attack to occur, who would look after the person, how would he or she get the assistance and reassurance they needed? The vulnerability grows from the feeling that once victims of agoraphobia are caught in the anxiety, they are suddenly unable to look after themselves and are therefore at the mercy of the place they find themselves in and the strangers around them. In its extreme form, agoraphobia and panic attacks can lead to a situation where people become housebound for numerous years.
It is important to note that agoraphobia is by no means a hopeless situation. Successful treatment is possible with the right combination of therapy and medication.
Panic Disorder
People who have repeated attacks or feel severe anxiety about having another attack are said to have panic disorder. Panic disorder is strikingly different from other types of anxiety disorders in that panic attacks are often sudden and unprovoked. An episode is often categorized as a positive feedback loop where the mental symptoms increase the physical symptoms, which increase the mental symptoms, and so on.

Treatment
Benzodiazepines like diazepam, lorazepam, alprazolam or clonazepam can be prescribed to be taken at the onset of the panic attack. Sometimes, the psychological knowledge of knowing that such medication is close at hand may be enough to prevent the panic attack. However, this form of treatment may be considered unfavorable by some doctors, because of the potential for abuse. Additionally, benzodiazepines will not treat the cause of the panic attacks. As such, some doctors may prefer to prescribe an antidepressant, particularly an SSRI (such as paroxetine or sertraline), which after an initial titration period may be effective at reducing anxiety. NaSSAs such as mirtazapine have also been found effective, particularly with individuals whose anxiety and panic causes insomnia. Individuals can also treat themselves during panic attacks by breathing into a paper bag (to decrease effects of hyperventilation), doing diaphragmatic breathing applying ice to the face or massaging the body to help stop the physiological reactions. Panic attacks are completely treatable and can be overcome with the correct combination of medication and therapy.

One particularly helpful and effective form of therapy is Cognitive Behavioral Therapy (CBT). Techniques used may include those based upon the concept that intentional exposure to the symptoms will help decrease the sufferer's fear of panic attacks (Symptom Induction). Symptom induction is in essence a form of systematic desensitization. That is, it intends to desensitize the afflicted from the symptoms of panic attacks. The therapist and patient discuss the nature of their attacks, and the symptoms which they fear most. The CBT typically consists of several sessions in which these symptoms are intentionally induced until the patient is less fearful. Inductions generally occur for one minute and may include: intentional hyperventilation, spinning in a chair, straw breathing, breath holding, head lifting, or running in place etc. The key to the induction is that the exercises should mimic the most frightening symptoms of a panic attack. Prior to inducing symptoms (hyperventilation, for example), the therapist asks the patient to rate their level of anxiety. Following the exercise, they rate their resulting level of anxiety. This is repeated at least five times until the anxiety rating is low. The patient's worst symptoms are focused on in this fashion, and the symptom induction cycle is repeated for each symptom.

Many people overcome panic disorders and sudden panic attacks on their own. It takes time, but in a sense, they ride out the panic attacks and eventually learn that nothing is going to happen during one. Often, they 'taper off' until they are not noticeable any longer. It is for this reason that some psychologists helping people with panic disorders induce them into an attack, so they can see for themselves that indeed, nothing will happen.

How do you learn to recognize your hidden real human emotions? What is the best treatment for anxiety and panic attacks?
Answer:
When you are young, you learn to identify feelings aided by other people. If people in the environment does not give good help, you may become confused in understanding your inner world.
A psychotherapist teaches patients to begin listening introspectively and search for what they feel and want. They become increasingly sincere and true to themselves, but can also be more troublesome for those in their surroundings as they no longer try to be accommodating.
If you do not have a therapist you can try to identify your feelings as follows:
Take the opportunity when you feel physically bad.
Lie down in a quiet room and close your eyes.
You will probably get a most unpleasant feeling.
This feeling of unpleasantness may become almost unbearable but concentrate on your real feeling in spite of this. You will gradually become more and more aware of of your real feelings.
Worry, loathing, shame, anger, fear and grief are examples of suppressed feelings.
The unpleasantness feels dangerous but it is in reality the suppressed feelings which are dangerous, not those you aware of.
Let the feeling of unpleasantness spread and make intensive contact with it. Allow yourself to express these feelings by making sounds and movements.
Within a quarter of an hour the feeling of unpleasantness will have probably disappeared and you have learnt what to do to begin solving your problems.