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 a “blocking” antibody, which reduces the symptoms of allergy when the substances are encountered in the future. Immunotherapy also reduces the inflammation that characterizes rhinitis and asthma. Immunotherapy can be “disease-modifying,” meaning we can eliminate or cure the allergy in many instances.
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 if the person seems to be selectively sensitive to several allergens and if medications are not effective or causing side effects.
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 allergic reaction or even anaphylaxis shortly after an injection. Therefore, immunotherapy requires medical supervision and should always be done in a medical setting.
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. In addition, the early introduction of immunotherapy for patients with allergic rhinitis may prevent them from developing asthma.