Unlike the relatively mild, brief anxiety caused by a stressful event such as a business presentation or a first date, anxiety disorders are chronic, relentless and can grow progressively worse if not treated." (Anxiety Disorders section, para.1) One should immediately see a doctor if he or she is suffering acutely from any of the following symptoms.
Panic disorder: According NIMH's website, " people with panic disorder have feelings of terror that strike suddenly and repeatedly with no warning. They can't predict when an attack will occur, and many develop intense anxiety between episodes, worrying when and where the next one will strike." (Anxiety Disorders section, para. 10)
One can experience panic attack any time, sometimes even during sleep. There is no specific duration of the attack. Sometimes it may last for more than half an hour, sometimes it may be of 10 minutes and sometimes even lesser. It may happen that a person experiences a panic attack only once in his lifetime. But if panic attacks are frequent then it is advisable to see a mental health care practitioner. As stated in the website of NIMH, "panic disorder is one of the most treatable of the anxiety disorders, responding in most cases to medications or carefully targeted psychotherapy."(Anxiety Disorders section, para. 18)
A person can get panic attack anywhere. For example, if a person experiences a panic attack while he is swimming, he may experience a terrible fear of drowning. The long-term effect on his personality would be that he might completely avoid going near a swimming pool, sea, river or pond and in extreme cases even his bathtub. Panic disorder causes acute depression and people suffering from it even turn alcoholic or drug addict to fight their depression.
Agoraphobia: According to Dr. Sanjay Chugh,
" The ancient term 'agoraphobia' is translated from Greek as 'fear of an open marketplace'. Agoraphobia today describes severe and pervasive anxiety about being in situations from which escape might be difficult or avoidance of situations such as being alone outside one's home, traveling in a car, bus or airplane, or being in a crowded area." (Mind/psychology/phobia/anxiety. asp section, para.10)
Therefore people suffering from agoraphobia start getting panic attacks the moment they are away from their homes or people they trust and get help from. The more the distance from their home and dear ones, the more is the intensity of their restlessness and fear. Hence, "severely agoraphobic people avoid going out altogether