An allergy is your body's overreaction to something that doesn't cause a problem for most people. One of the marvels of the human body is its ability to defend itself against harmful invaders, such as viruses and bacteria. With allergies, your body's immune system works too well and overreacts by attacking harmless things such as animal danders, dust, molds, or pollen. The body treats these as invaders and releases chemicals to defend itself. It is those chemicals that causes allergic symptoms that can range from mild to severe. Sometimes the symptoms are just annoying. Sometimes they are deadly.
There are hundreds of ordinary things that can trigger an allergic reaction. These are called "allergens." Some of the most common are plant pollens, molds, household dust (dust mites), cockroaches, pets, chemicals, foods, medicines and insect stings.
Anyone can be allergic - young or old, male or female. Asthma and allergies are more common in children, but can happen for the first time at any age. Sometimes allergy symptoms that start in childhood can disappear for many years and then recur during adulthood. Although the reasons are not yet understood, allergies and asthma do tend to run in families. If you have allergies, it's very likely that one or both of your parents do too.
An allergic reaction can affect any part of the body , but its symptoms are most often felt in the nose, eyes, lungs, lining of the stomach, sinuses, throat and skin. These are places where immune system cells stand ready to fight off invaders that are inhaled, swallowed or that come in contact with the skin.
Allergic diseases and reactions include:
In addition to treating and controlling these conditions, the allergist is an expert in treating immune system problems that might cause repeated infections such as pneumonia, ear infections or bronchitis.