When appropriate medications and avoidance of allergens are inadequate for control of respiratory allergy (allergic rhinitis or asthma), allergen immunotherapy (allergy injection treatment) may be indicated. The treatment consists of repeated injections of one or more mixtures of extracts of allergens over a period of several years. Studies of oral immunotherapy with allergens (drops under the tongue) suggest that this might be effective under certain circumstances, but has not been proven to be effective for treatment of sensitivities to multiple allergens seen in most allergic patients.
In the first year of treatment, the injections redirect the immune system toward more normal functioning. This has the effect of suppressing the levels of IgE antibodies and reducing allergic inflammation, so that tolerance of exposure to allergen steadily improves.
The allergens selected for treatment are determined by the allergist to be important in provoking disease in the patient. Initially the injections are very small doses of weak allergen extracts given once or twice a week, and the doses are progressively increased as the reactivity of the patient's immune system to the allergens decreases.
Allergen immunotherapy has been proven by scientifically controlled studies to be effective in reducing symptoms. Although immunotherapy never provides a permanent cure for asthma or allergic rhinitis, it reduces the need for medications in many patients with allergic rhinitis and asthma. Because there is a risk of allergic reactions to the injections that varies from one patient to another, the allergist gives advice on the balance between benefits and risk before starting treatment.
Allergy injection treatment is more effective for allergy to pollen, cats and house dust mites than it is for mold allergy. This is fortunate for us in the desert, where mold allergy is less of a problem than in more humid climates and where both allergic rhinitis and allergic asthma are commonly triggered by pollen. Immunotherapy appears to be less effective in the treatment of allergic asthma than in the treatment of allergic rhinitis, but patients who have both conditions usually benefit from immunotherapy. It is not indicated for treating food allergy.
Since improvement in symptoms is normally delayed for 9-12 months, medications taken before starting the injections must NOT be stopped during this period. Medication requirements usually decrease after one year of treatment, but some patients never become independent of medications.