Allergen Immunotherapy
Allergen specific immunotherapy (also called ASIT, desensitization, hyposensitization) is the technique of treating IgE-mediated allergic disease with increasing doses of the causal allergen in order to decrease sensitivity to the offending allergen. Two methods are advocated: sublingual immunotherapy (SIT) and injection immunotherapy (IIT) with the offending allergen. The patient should meet three important conditions for consideration of ASIT. Firstly, there must be a convincing history of clinical symptoms severe enough to justify the time commitment, cost, and risks of immunotherapy. Secondly, the patterns of symptoms are not well controlled by avoidance measures and acceptable levels of drug therapy, or both. Thirdly, the patient should show an IgE-mediated allergic response (detected through CAP RAST tests) to specific allergens that can be used for immunotherapy.

Multiple allergen reactions need detailed consideration of the potential long-term benefits of immunotherapy with one or more causal allergen. If care is not taken in selection of the patients at the onset of therapy, the success rate after 3 years of immunotherapy may be dismal. In Malaysia there are special problems with immunotherapy to dust mites allergens since several non-cross reacting species are present in homes.