What Is Allergy?

• Three General Rules Of Allergies
• Common Misconceptions About Allergies

Allergy is not a disease in the typical sense. It is an exaggeration of the body's natural immune defenses. Mild allergies can be annoying, and severe forms can be very serious or even deadly.

Allergies vary in the types of symptoms they cause and the best methods to prevent and treat them. The type of allergy you have depends on the allergen that provokes your symptoms (such as mold or cat dander), the specific areas of the body affected by allergy symptoms (such as airways, skin or nose) and whether or not the reaction stays in one place or is triggered throughout the body. For example, allergic asthma, a type of allergy that may be triggered by a variety of airborne substances, is an exaggerated immune reaction confined to the airways of the lung. The symptoms of hay fever or seasonal allergies, caused by pollen in the air, are usually limited to the nose, eyes and sometimes the sinuses or the airways. Similar symptoms can be caused year-round (called "perennial" allergies) by indoor airborne allergens, such as dust mite or cockroach allergens, mold, or pet dander. On the other hand, an allergic reaction to an insect sting can trigger a severe response that affects the whole body. This response, called anaphylaxis, is potentially fatal.

Once you learn what type of allergy you have, you can learn to prevent and treat it on your own. You can also learn how to recognize dangerous types of allergic reactions and when to get help.

Three General Rules of Allergy

Although each type of allergy behaves differently, some general rules apply:

• Allergies always involve the immune system.
  
• A reaction occurs after exposure to an allergen. The timing may be immediate - soon after contact with an allergen - or delayed - up to two days after contact (such as with poison ivy).
  
• Prevention is just as important as treatment, if not more.
  

The Role Of the Immune System

All allergies are an immune reaction to a normally harmless antigen. An interesting quality of the immune system is that it is capable of learning. Each time you are exposed to an allergen, the immune system takes less time to react. Sometimes, this reaction is more dramatic than the first; in some instances, serious, potentially life-threatening symptoms develop on subsequent exposure to an allergen.

Certain allergens are more likely to cause life-threatening symptoms (anaphylaxis) than others. It is important to avoid a second exposure if you have had a reaction in the past to insect stings, peanuts, latex or penicillin.