Allergen injections (immunotherapy) are a type of therapy in which minor doses of chemicals to which a person is allergic (allergens) are given under the skin. Over time, the body may become less sensitive to the allergens, which means the person may have fewer signs and symptoms.
Allergen injections are administered after elaborate skin testing for an allergic reaction. During initial therapy, allergen injections are administered once or twice per week. At first, a lesser amount of allergen is given. The amount is then increased slightly each time, unless an intense allergic reaction occurs. After four to six months of weekly injections, the injection can contain a high level of allergen. This is referred to as the maintenance dosage.
Once the maintenance level is reached, the person receives the same dosage every two to four weeks for another four to six months, and should visit a physician to be monitored every six to twelve months.
After three to five years of allergen shots, the person and the physician need to decide whether to discontinue immunotherapy or to keep going. Children who are treated with allergen injections often cease them after this time. However, these younger patients often benefit from continuing with the injections.
What to Expect from Allergen Injections and Immunotherapy
Allergen injections are given in the doctor's office. The person remains in the office for a short period after receiving the injection, to be monitored for possibly dangerous reactions (anaphylaxis) to the injected allergens.
Inflammation and warmth at the injection sites are common but disappear after a short time.
Purpose of Allergen Injections and Immunotherapy
Allergen injections may be used to help deal with bronchial asthma if it is clear that someone has asthma signs and symptoms when introduced to an allergen (allergic asthma attack). Symptoms may occur all year or during a significant part of the year.
They are also used when prescription drugs have not prevented symptoms, numerous medications are required, or the person does not want to use medication indefinitely.
Risks Associated with Immunotherapy for Asthma
Allergen injections are non-hazardous when the shots are administered properly. Inflammation and warmth at the shot site are usual. Generally, systemic (body) responses such as hives, asthma signs and symptoms, and decreased blood pressure are not common.
However, individuals with asthma may be at increased risk for a serious reaction (anaphylaxis) to the injections and, potentially, death. The person's asthma should be well controlled before he or she gets allergen shots.
Due to the possibility of anaphylaxis, the injections are given in a doctor's clinic, where emergency care can be administered when necessary. Most reactions to allergen injections occur twenty to thirty minutes after the injection, and the person should remain at the doctor's clinic for a minimum of this amount of time.
References
Joint Task Force on Practice Parameters. (2003). "Allergen immunotherapy: A practice parameter." Annals of Allergy, Asthma, and Immunology. (90); 1, Supplement 1: S1–S40.
National Institutes of Health. (1997). "Expert Panel Report 2: Guidelines for the Diagnosis and Management of Asthma." Clinical Practice Guidelines (NIH Publication 97-4051). Bethesda, MD: U.S. Department of Health and Human Services.
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