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Allergic diseases can vary from mild to life-threatening and affect as many as 40 to 50 million Americans*.

What are allergies?

An allergy is a heightened sensitivity to a foreign substance (called an allergen) that causes the body’s defense system (the immune system) to overreact when defending itself.

Normally, the immune system would only react if a harmful substance, such as virus or bacteria, attacks the body. For people with allergies, their immune system is working overtime, and it over reacts even when relatively harmless substances, allergens, are present. The severity of an allergic reaction can vary from mild discomfort to life threatening.

Allergens can stimulate an immune response when they are inhaled, ingested, touched or injected such as a medication.

Allergies are categorized by the type of trigger, or where symptoms appear on the body. For instance, if categorized by the type of trigger you would find the following common allergies:

Alternatively you could categorize the allergies by area of the body where symptoms occur. The following are common allergic reactions:

What is the mechanism of an allergic reaction?

Allergies occur when the immune system overreacts to a normally harmless substance called an allergen.  Allergy reactions are mediated via  proteins called antibodies.  These proteins normally function to protect our bodies from foreign invaders by recognizing and destroying them.  When a person has an allergy, a specific antibody called immunoglobulin E or IgE improperly recognizes the allergen as foreign and causes an immune response.

When allergens first enter the body of a predisposed individual, the immune system produces allergen-specific IgE antibodies to that substance.  These antibodies then attach themselves to a type of white blood cell called a mast cell.  The next time, an offending allergen enters their body, the IgE antibody recognizes the allergen and quickly initiates  the release of chemicals including histamines from those mast cells. Those chemicals cause the symptoms seen in allergic reactions and anaphylaxis.

What are the symptoms of allergies?

Allergy symptoms vary greatly  in severity and type. 

They can include:

  • Runny, stuffed or itchy nose
  • Itchy, red, swollen or burning eyes
  • Headaches
  • Itchy, red or swollen skin
  • Hives
  • Difficulty breathing, coughing or wheezing
  • Nausea and vomiting
  • Anaphylaxis

How are allergies diagnosed?

If allergies are suspected, your allergist will ask you about your health and family history and perform a physical exam. He or she will ask you to fill out a questionnaire about your symptoms to determine what type of symptoms you have, their severity and where and when the occur.  Your allergist may perform allergy tests to determine what you are allergic to and how severe the allergy is.    These tests include skin tests via prick technique or intradermal injection, blood tests (RAST) or challenge testing.The test results alone do not diagnose allergies.  All test results must be interpreted together with the medical history.

Who gets allergies?

Allergies tend to run in families. If you have allergies, it’s very likely that at least one of your parents does too. Exposure to allergens at times when the body’s defenses are weak, such as after an illness or during pregnancy, also may play a role in developing allergies. Although allergies are most common in children, they can occur at any time and any age.  Sometimes allergies go away, but they also can come back years later.

How are allergies treated?

Treatment is determined on an individual basis as prescribed by your physician.  Please contact our office to schedule an appointment with one of our allergy and asthma specialists.

What are the complications of allergies?

The most serious complication is a which is  a life-threatening allergic reaction.

Other complications include:

  • Breathing problems 
  • Discomfort during the allergic reaction
  • Drowsiness and other side effects of medicines

Can you prevent allergies?

Breast-feeding children for at least 4 months or more may help prevent atopic dermatitis cow milk allergy, and wheezing in early childhood. 

Changing a mother’s diet during pregnancy or while breast-feeding does not seem to help prevent allergy-related conditions.

For most children, changing diet or special formulas does not seem to prevent these problems. 

The timing of introduction of solid foods in general, as well as use of several specific foods, can help prevent some allergies.

There is also evidence that infants exposed to certain airborne allergens (such as dust mites and cat dander) may be less likely to develop related allergies. This is called the “hygiene hypothesis” and it developed from observations that infants on farms tend to have fewer allergies than those who grow up in environments that are more sterile.


*Airborne allergens: Something in the air. National Institute of Allergy and Infectious Diseases. NIH Publication No. 03-7045. 2003.

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