While there are different types of conjunctivitis, rhinitis and asthma, about 50 to 70 percent of Americans suffer from allergy-induced types of these conditions. An allergy is defined as an abnormal sensitivity to a substance normally tolerated and generally considered harmless such as pollen, dust mites, food, drugs or insect stings. This means that while some allergens are tolerated by most people, they can induce an allergic reaction in others, mainly due to the presence of the IgE antibody. IgE, one of our immunoglobulins ( the others are IgG, IgA, IgM and IgD), is a key player in allergic reaction.
While avoiding offending allergens is always the first step in preventing and treating allergic disorders, this approach is often impractical or impossible. For instance, dust mites are extremely difficult to completely eradicate. And although medications can be a very effective way to control allergic reactions, many people suffer symptoms despite their use. In many cases, immunotherapy (also known as allergy injections or desensitization) is the most effective form of treatment for allergic rhinitis, conjunctivitis and asthma.
To identify offending allergens, your allergist must first review your history and perform a skin test by applying small amounts of allergens on the skin and pricking. Within 15 minutes, results from skin testing are apparent and show a reaction by producing a "wheel" or round red raised area at the particular skin test site.
Immunotherapy can alter and lessen the allergic reaction via injections of adequate triggering allergens. Specifically, immunotherapy works in the body by decreasing the production of IgE, and by initiating the production of other immunoglobulins which further interferes with the IgE. Typically, an effective immunotherapy program requires regular injections for at least three to five years. The injections are a specifically formulated and diluted solution comprised of inhalant allergen extracts to which you are allergic, such as tree, grass, weed pollen, mold spores, dust mites or animal dander.
Your allergist will gradually build up your dose by increasing the amount of allergen concentration weekly or twice a week until maximum concentration is reached or side effects occur. At this time, you start what is known as a dosage maintenance period. During the maintenance period, you will receive a fixed amount of allergens, with extended intervals between injections, from two weeks to one month apart, depending on your progress.
The state of desensitization can be maintained for several years, or in some cases for life, with no need to restart injections. However, in some cases, the reappearance of allergic symptoms may occur. In such instances, your allergist will need to evaluate your symptoms and consider the possibility of restarting immunotherapy or other treatment.
By Dr. Yong Tsai
April 9, 2012