Considered as one of the major disabling illnesses, allergies afflict more than 40 million people in the in United States alone. As you know, our immune system protects our body from all types of foreign substances and dangerous microorganisms, called antigens, like viruses, bacteria etc. It does this by producing a counter chemical called an antibody, which fights these antigens. The antibodies bind themselves to the antigens, which sets off a reaction. This reaction between antibody and antigen ignites a series of events, all designed to protect the body from infections.

The immune system is programmed to ignore harmless substances like food, pollen etc. However, sometimes it mistakes these innocuous substances for harmful invaders and attacks them like it would an antigen, by releasing powerful chemicals like histamines, to destroy them. What happens is that when the body is exposed to an allergen, it launches its counter offensive attack by releasing an antibody called immunoglobulin E (IgE) through its mast cells. The mast cells are a distinctive sets of cells of the immune system located in areas where the body comes into contact with the outside world , like the mucous membranes of the eyes and other areas, and the linings of the respiratory and digestive systems. Their function is to guard the body from outside influences.

When IgE encounters allergens, it triggers off the release of the chemical histamine, from the mast cells. When the histamine binds it self to the surrounding cells, through histamine receptors, the neighboring cells become leaky, causing fluid collection, redness and swelling, all of which are symptoms of an allergic reaction. Histamines also trigger off pain receptors which cause itchiness in the eyes, nose and throat, all symptoms of allergic rhinitis.

An allergy then is a condition in which the body attacks harmless substances like dust, pollen, food etc and releases antibodies to subdue them. It is the release of histamines that produces the disagreeable symptoms that are associated with allergies. Allergic reactions are, most often, instantaneous, for e.g. one may break out into a rash, or develop a sneezing fit. People who are allergic to one substance will often find that they are sensitive to a number of other substances.

These offending agents, called allergens, range from dust, pollen, mold, mildew, food, rubber, insect stings and even medicines. Common food allergens include peanuts, fish, eggs and milk. An allergy is one of the most common causes for asthma. An allergy can cause the irritation, swelling and inflammation of the air passages, which causes asthma.

Studies estimate that over 20 percent of Americans suffer from some type of allergy, making allergies a principal source of chronic disease in the country.