Allergen immunotherapy injections, or allergy shots, are prescribed for patients with allergic rhinitis commonly known as hay fever, allergic asthma or life-threatening reactions to insect stings. Immunotherapy is a medical treatment that has the potential to modify allergic disease. Studies have shown that it plays a protective role in allergic children, possibly preventing asthma from developing in patients with allergic rhinitis. Immunotherapy is considered for individuals who have moderate or severe symptoms not adequately controlled by environmental control measures and/or medications. Immunotherapy is also appropriate when chronic medication use is not desired, or not safely tolerated.
Effectiveness: Allergen immunotherapy (allergy shots) modifies the immune system, which results in reduced allergic symptoms to common allergens including pollens, molds, animal dander and dust mites. In most cases, the initial 6 to 12 month course of allergy shots is likely to gradually decrease sensitivity to airborne allergens and continuation of injections leads to further improvement. The injections do not cure patients but diminish sensitivities, resulting in fewer symptoms and use of fewer medications. It is important to maintain shots at the proper time interval; missing your shots for a short time may be acceptable but an appropriate adjustment in the dose of vaccine may be necessary for long lapses in injections.
There are generally two phases to immunotherapy: a build-up phase and a maintenance phase.
Build-up phase: Involves receiving injections with increasing amount of allergen. The frequency of injections during this phase ranges from 1 to 2 times a week, though more rapid build-up schedules are sometimes used. The duration of the build-up phase depends on the frequency of the injections, but typically takes from 3 to 6 months.
Maintenance phase: This phase begins when the effective therapeutic dose is reached. The effective therapeutic dose is based on recommendations from a national collaborative committee called the Joint Task Force for Practice Parameters: Allergen Immunotherapy A Practice Parameter and was determined after review of several published studies on immunotherapy. The effective maintenance dose may be individualized for a person based on their degree of sensitivity (how allergic they are to the allergens in their vaccine) and their response to the immunotherapy build-up phase. Once the target maintenance dose is reached, the interval between the allergy injections can be increased. The interval between maintenance immunotherapy injections ranges from 2 to 4 weeks, but is individualized to provide the best combination of effectiveness and safety for each person. Shorter intervals between allergy injections may lead to fewer reactions and greater benefit in some people.
Reactions: It is possible to have an allergic reaction to the allergy injection itself. Reactions can be local (swelling at the injection site) or systemic (affecting the rest of the body). Systemic reactions include nasal congestion, runny nose, itchy eyes, hives, flushing, lightheadedness, wheezing or shortness of breath, and very rarely, life threatening reactions. Some conditions can make allergic reactions to the injections more likely: heavy natural exposure to pollen during a pollen season and exercise after an injection. Serious systemic reactions can occur in patients with asthma that has worsened and is not well controlled on recommended medications. Allergy shots are not administered when asthma is poorly controlled, or you are experiencing fever or illness. Reactions to injections can occur, however, even in the absence of these conditions. Taking a beta-blocker medication places you at higher risk of severe reaction, as it masks early symptoms and may prevent the effectiveness of emergency rescue medications, such as epinephrine.