Allergy Shots (immunotherapy)
PURPOSE
The purpose of allergen immunotherapy, also known as "allergy shots", is to decrease your sensitivity to substances called allergens to which you are allergic, so future exposures to those substances will result in fewer and less severe symptoms.
When immunotherapy injections are repeated, the body builds resistance or "immunity" to the allergen through the formation of "blocking" (also known as protective) antibodies. These changes in your immune system may allow you to tolerate exposure to the allergen with fewer symptoms.
Many carefully performed studies have shown that immunotherapy decreases allergic symptoms and may improve asthma. Immunotherapy may also prevent the development of new allergies and, in children, may prevent the progression of allergic disease from allergic rhinitis to asthma.
INDICATIONS
To be a candidate for immunotherapy, you must have documented allergies determined by allergy testing. In addition, you should have symptoms, whether they are nasal, eye, respiratory, etc., upon exposure to the substance to which you are allergic.
ADMINISTRATION
In the course of immunotherapy, very small doses of allergen are given to the patient and are gradually increased each week. This gradual build-up of the allergen decreases the possibility of the injection itself causing an allergic reaction. Depending on the number and type of allergies you have, either one, two, or more injections may be required during each injection visit. Following the weekly build-up phase, which generally occurs over 4-5 months, maintenance injections are typically given monthly.
EFFECTIVENESS and DURATION OF TREATMENT
Improvement in your allergy symptoms is not immediate. Patients may not begin to see improvement in symptoms for 6-9 months, and full benefits may not be evident for 12-18 months. A majority of patients improve while receiving immunotherapy, which means that symptoms are reduced, but not necessarily completely eliminated.
If a patient is so improved that symptoms are lessened or do not occur during the allergy season, then after three to five years the injections may be stopped. Some individuals may relapse and subsequently need to go through weekly injections again. Everything considered, it is recommended that all patients discontinue therapy after five years to determine if continued therapy is necessary. Immunotherapy for insect induced anaphylaxis is an exception to these general rules.
ADVERSE REACTIONS
Immunotherapy is typically tolerated very well. However, since you are receiving injections of allergens to which you are allergic to, there is a risk of an adverse allergic reaction. Some adverse reactions may be life-threatening and may require immediate medical attention.