Allergen Immunotherapy is defined as the repeated administration of specific allergens to patients with immunoglobulin E (IgE) mediated conditions for the purpose of providing protection against the allergic symptoms and inflammatory reactions associated with natural exposure to these allergens. Other terms that have been used for allergen immunotherapy include hyposensitization, allergen specific desensitization, and the lay terms allergy shots or allergy injections.
Phases of Allergen Immunotherapy
There are two phases of allergen immunotherapy administration: the initial build-up phase and the maintenance phase.
1. Build-up phase
The immunotherapy build-up phase (also called updosing, induction, or the dose-increase phase) entails administration of gradually increasing doses during a period of approximately 8 to 28 weeks. In conventional schedules, a single dose increase is given on each visit and the visit frequency can vary from 1 to 3 times a week. Accelerated schedules, such as cluster or rush immunotherapy, are also included in the build-up phase. These schedules entail administration of several injections at increasing doses on a single visit.
Cluster immunotherapy is an accelerated build-up schedule that entails administering several injections at increasing doses (generally 2-3 per visit) sequentially in a single day of treatment on nonconsecutive days. The maintenance dose is generally achieved more rapidly than with a conventional (single injection per visit) build-up schedule (generally within 4-8 weeks).
Rush immunotherapy is an accelerated immunotherapy buildup schedule that entails administering incremental doses of allergen at intervals varying between 15 and 60 minutes over 1 to 3 days until the target therapeutic dose is achieved.
2. Maintenance phase
The maintenance phase begins when the effective therapeutic dose is reached. Once the maintenance dose is reached, the intervals between allergy injections are increased. The dose generally is the same with each injection, although modifications can be made based on several variables (i.e., new vials or a persistent large local reactions (LLR) causing discomfort). The intervals between maintenance immunotherapy injections generally range from 4 to 8 weeks for venom and every 2 to 4 weeks for inhalant allergens, but can be advanced as tolerated if clinical efficacy is maintained.
Not all place of services are covered for allergy immunotherapy. See eligible Place of service for coverage.