Desensitization for allergies (immunotherapy)


A friend of mine is interested in desensitization therapy for cat allergy. He has consulted two allergists: one claimed a nearly 100 percent success rate; the other suggested the procedure was virtually worthless, and possibly dangerous. I suspect the truth lies somewhere between these two extremes. Is there any reliable information concerning the success rate for this procedure, what kinds of problems might be encountered, and how long one might expect it to take?

— Fur ball


Dear Fur ball,

Cough, sneeze, hack — ugh, allergies.  Like your friend, so many people are looking for a long-term solution to allergy issues.  As you noted, desensitization therapy, also called immunotherapy, is considered to be a preventive treatment for allergies. In allergy prevention, immunotherapy involves injecting gradually larger doses of the allergen, or substance, to which the person is allergic, into the skin of her/his arm. The purpose of this process is to make the immune system less sensitive to the allergen, probably through the production of a blocking antibody, which decreases allergy symptoms if the allergen is encountered in the future.

The immunotherapy process is based on using a purified extract of the allergen that is injected once a week for thirty weeks, after which injections can be reduced to once every two weeks, and eventually be decreased to one time every four weeks. The duration of the entire therapy is three to four years. Immunotherapy is generally recommended for people who have selective sensitivity to specific allergens. One rare complication that can arise is anaphylactic shock, or severe allergic reaction, occurring shortly after an injection. To prevent this risk, it's good to avoid immunotherapy at a time of exposure to the substance causing the allergy. As far as the success rate of desensitization therapy for allergy sufferers, according to the National Institute of Allergies and Infectious Diseases no statistics are available.

The best thing to do, is make an appointment with a health care provider who will discuss the various pros and cons of the procedure. With any luck and some patience, allergies need not be a difficult or sneezy issue.

Last updated Jul 02, 2015
Originally published Apr 10, 1995

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