An allergy is a reaction to a substance that is usually considered harmless to non-allergic individuals. The body's immune system identifies allergens as foreign invaders and produces IgE antibodies against them. Approximately 60 million Americans suffer from allergies. Different allergens are found throughout the United States and in varying concentrations. There is no place one can go to totally avoid allergens in the United States. Allergies can develop at any age. Once someone is known to be allergy prone, they have a tendency to exhibit allergies anytime throughout their lifetime. Avoidance of an allergen is the most effective treatment for allergies. The development of specific allergies is related to repeated exposure to that allergen.
What causes nasal or eye allergies?
Four basic elements are involved in allergy: the allergen, the antibody, the mast cells (along with other effector cells) and the affected body organ. The allergen enters the body and comes in contact with the lymphocytes of the immune system which are responsible for producing a special type of antibody called immunoglobulin E (IgE). IgE attaches itself onto the mast cells. Mast cells are found in the eyes, nose, skin, lungs, heart, intestine and other areas of the body. Mast cells contain and produce many chemical mediators including histamine, prostaglandins and leukotrienes. When the mast cell with IgE on its surface is exposed to an allergen, an allergic reaction occurs, triggering a release of chemical mediators. These mediators cause the symptoms of an allergic reaction.
What are the symptoms of allergies?
Common symptoms that someone with nasal allergies can present with are sneezing, runny nose, nasal congestion, headaches (usually frontal or behind the eyes), increase postnasal drip, sore or itchy throat, irritability and malaise or fatigue. Patients with eye allergies may complain or eye redness, tearing, itching, or swelling. Many but not all patients with nasal allergies can also present with symptoms of coughing, shortness of breath, wheezing and skin rashes.
How are allergies diagnosed?
The doctor will review your medical history and perform a physical examination. He may perform skin test to identify the most likely allergens causing your symptoms. Skin tests for IgE-mediated disease are acknowledged to be the most clinically applicable techniques in the assessment of allergic patients.1 Blood tests (immunoassays) can also be ordered to evaluate allergen triggers but these tests are not considered as sensitive as skin tests. The precise sensitivity of these immunoassays compared with prick/puncture skin tests has been reported to range from 50% to 90% with the average being about 70 to 75% for most studies. 1 Blood tests can be used to diagnose allergies in any patient but are most useful in situations when the patient can not or should not undergo skin testing (i.e. very young infants, patients that are very old, patients with active diffuse skin disease, and patients that can not stop taking antihistamines).
How do I treat my allergies?
Your doctor may give you some recommendations depending upon the allergy and the severity of your symptoms. These can include avoidance of the allergens, environmental control measures, medications and allergy shots (immunotherapy).
What is the prognosis?
There is no cure for nasal or eye allergies. Some patients may experience improvement of their symptoms on rainy days, when the pollen levels are lower or by avoiding allergens. Most medications can treat the symptoms of allergies but do not change how the body reacts to the allergens. Currently, the closest treatment to an actual cure is allergy immunotherapy (allergy shots). The exact mechanism by which immunotherapy works is not completely understood but it is believed that it may induce a tolerance to allergens; making these allergens less capable of activating mast cell (see above) and inducing an allergic response.
1. from AAAAI.org