What are allergies?

Allergies are the result of an overactive immune system that reacts to harmless substances in the environment called allergens.  The most common allergens in the air include pollens, molds, animal dander, cockroach, and dust mites.  People can also have allergic reactions to food, drugs, latex, and stinging insects.  Allergies are very common and the incidence is increasing.  Approximately 1 out of every 5 Americans suffers from an allergic condition. 

One function of our immune system is to defend our bodies against harmful things in the environment such as bacteria and parasites.  One way it does so is by making antibodies to fight off these harmful things.  When a person who is predisposed to allergies first encounters an allergen, his immune system reacts to it as if it were a parasite.  It makes IgE type antibodies against it.  This antibody then circulates in the blood and finds cells called mast cells that it attaches to.  When the person is re-exposed to that allergen, it binds to the IgE antibody on the mast cells, causing them to release different chemical mediators such as histamine that cause allergic symptoms. 

Typical allergy symptoms from airborne allergens include nasal congestion, runny nose, sneezing, itchy eyes, tearing, coughing, and wheezing, and occassionally, hives and swelling.  Allergic reactions can range from mild to severe.  Life-threatening allergic reactions are referred to as anaphylaxis.  They are usually caused by foods, include:  drugs, or insect stings. 

Common allergic diseases:

  • Allergic rhinitis, also known as hay fever.
  • Allergic conjunctivitis (allergies of the eye).
  • Asthma.
  • Atopic dermatitis.
  • Urticaria, also known as hives.
  • Severe allergic reactions to substances such as food, latex, medications, and insect stings.

An allergist/immunologist is best suited to diagnose and treat allergic conditions.  He will perform allergy testing as indicated to diagnose your allergy.  He can then recommend appropriate treatment options.


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