Allergen immunotherapy works like a vaccine.
Your body responds to the sub-lingual or injected amounts of a particular allergen, given in gradually increasing doses, by developing an immunity or tolerance to the allergen(s). As a result of these immune changes, immunotherapy can lead to decreased, minimal or no allergy symptoms when you are exposed to the allergen(s) included in the allergy vaccine.
There generally are two phases to immunotherapy: a build-up phase and a maintenance phase.
► Build-up phase: involves receiving injections or drops with increasing amounts of the allergens. The frequency of injections (for those receiving shots) during this phase generally ranges from 1- 2 times a week, though more rapid build-up schedules are sometimes used. The duration of this phase generally ranges from 3-6 months with injections and 10 days for sub-lingual.
► Maintenance phase: This phase begins when the effective therapeutic dose is reached. The effective maintenance dose is different for each person, depending on their level of allergen sensitivity and their response to the immunotherapy build-up phase. Once the maintenance dose is reached, there will be longer periods of time between immunotherapy treatments. The interval between maintenance immunotherapy using injections generally ranges from every 2 to 4 weeks.
If taking drops, you will follow the regimen determined by your physician at home and usually on a daily basis. The benefits of immunotherapy, in terms of reduced allergy symptoms, can begin during the buildup phase but may take as long as 12 months on the maintenance dose. Improvement with immunotherapy may be progressive throughout the immunotherapy treatment period. Effectiveness of immunotherapy appears to be related to length of treatment and the dose of the allergen. Failure to respond to immunotherapy may be due to several factors including:
- Inadequate dose of allergen in the allergy vaccine
- Missing allergens not identified during the allergy evaluation
- High levels of allergen in the environment
- Significant exposure to non-allergic triggers (i.e. tobacco smoke)