Immunotherapy is a preventive treatment for allergic reactions to substances such as grass pollens, house dust mites and bee venom. Immunotherapy involves giving gradually increasing doses of the substance, or allergen, to which the person is allergic. The incremental increases of the allergen cause the immune system to become less sensitive to the substance, probably by causing production of a "blocking" antibody, which reduces the symptoms of allergy when the substances is encountered in the future. Immunotherapy also reduces the inflammation that characterizes rhinitis and asthma.
Before starting treatment, the physician and patient identify trigger factors for allergy symptoms. Skin or sometimes blood tests are performed to confirm the specific allergens to which the person has antibodies. Immunotherapy is usually recommended only if the person seems to be selectively sensitive to several allergens.
How allergy immunotherapy is done
An extract of a small amount of the allergen is injected into the skin of the arm. An injection may be given once a week (sometimes more often) for about 30 weeks, after which injections can be administered every two weeks. Eventually, injections can be given every four weeks. The duration of therapy may be three to five years, sometimes longer.
There is a small danger of anaphylactic shock (a severe allergic reaction) shortly after an injection. Therefore, immunotherapy requires medical supervision.
Immunotherapy for asthma
Immunotherapy is effective in the treatment of allergic asthma. Allergy shots can help relieve the allergic reactions that trigger asthma episodes, thereby enhancing pulmonary function and decreasing the need for asthma medications.