What causes these attacks?

There are many physical and psychological factors, which may be interwoven. You may experience panic only in response to a particular situation, such as flying or visiting the dentist. Or you may feel perfectly fine during a stressful event, but may have an attack later. This is because adrenalin levels don’t drop straight away. Any major life changes and events can trigger panic attacks.

Childhood influences
Incidents in childhood, and the way you were brought up and taught to think about yourself, can make you vulnerable to panic attacks later on. If you experienced great fear at being separated from a parent, you may have gone on to develop school phobia. As an adult, you may then have panic attacks when threatened with the loss of a support system or of someone who is important to you. Adult survivors of abuse in childhood also frequently suffer panic attacks.

Personality traits
If you are always anxious, you are more likely to have panic attacks. Being over-critical and disapproving of yourself, and striving to conform to the expectations of others, is common in people who panic. You may have difficulties in expressing your own needs and asserting yourself.

Physical causes
There are a number of physical causes that could be causing or contributing to your panic attacks:

Unstable blood sugar levels (hypoglycaemia) can be the result of poor eating habits, dieting and fasting.
Over-breathing (hyperventilation) happens when you are under stress, though you may not be aware of it. Your breathing becomes more rapid, in order to meet the body's demand for more oxygen for the muscles. As a result, you breathe out more carbon-dioxide than normal, which can bring on panic symptoms.
Digestive problems, particularly food allergies, may be to blame.
Taking antidepressants, particularly the newer ones, may produce panic attacks, especially at first.
Caffeine, cigarettes, alcohol, and certain street drugs (such as LSD, marijuana and cocaine) can bring on a panic reaction.
Withdrawing from any drug that has a sedative effect, such as nicotine, alcohol and tranquillisers, can do the same.
Some prescription medication, including some amphetamines, steroids, anti-asthma drugs, and even nasal decongestants have been reported to increase anxiety.
Sometimes, problems with the way the brain works (known as organic brain dysfunction) will cause balance, coordination and visual difficulties that make people very vulnerable to stress, and may contribute to agoraphobia.
Being in chronic pain can be another cause of panic attacks, as can simple jet lag.