If you suffer from allergic asthma, rhinitis, conjunctivitis or stinging insect allergies, you may benefit from immunotherapy. Allergen immunotherapy, also known as allergy shots, is a form of treatment that is aimed at decreasing sensitivity to allergens. Allergens, such as pollen, mold and animal dander, are substances that trigger allergy symptoms when an allergic person is exposed to them.
Patients who receive immunotherapy are injected with increasing amounts of an allergen over several months. Immunotherapy has been shown to prevent the development of new allergies and, in children, it can prevent the progression of allergic disease from allergic rhinitis to asthma. It can also lead to the long-lasting relief of allergy symptoms after treatment is stopped.
When can immunotherapy help?
Immunotherapy may be beneficial for people with allergic asthma, rhinitis, conjunctivitis or stinging insect allergies. It is not used to treat food allergies. The best option for people with food allergies is to strictly avoid that food.
Both children and adults can receive immunotherapy, although it is not recommended for children under five because of the difficulties younger children may have in cooperating with the immunotherapy program. When considering immunotherapy for an elderly person, medical conditions such as cardiac disease should be taken into consideration and discussed with your allergist/immunologist first.
An allergist/immunologist will base the decision to begin immunotherapy on:
- Length of allergy season and severity of symptoms
- How well medications and/or environmental controls alleviate allergy symptoms
- Desire to avoid long-term medication use
- Time (immunotherapy requires a significant time commitment)
- Cost (this may vary depending on region and insurance coverage)
Where should immunotherapy be given?
Immunotherapy should only be given under the supervision of a specialized physician in a facility equipped with proper staff and equipment to identify and treat adverse reactions to allergy injections. Ideally, immunotherapy should be given in the prescribing allergist/immunologist’s office, but if this is not possible, your allergist/immunologist should provide the supervising physician with comprehensive instructions about your immunotherapy treatment.
How does immunotherapy work?
Immunotherapy works like a vaccine. Your body responds to the injected amounts of a particular allergen, given in gradually increasing doses, by developing immunity or tolerance to the allergen(s). As a result, allergy symptoms decrease or minimize when a patient is exposed to that allergen in the future.
Two phases are involved in immunotherapy:
Build-up phase – This involves receiving injections with increasing amounts of the allergens about one to two times per week. The length of this phase depends upon how often the injections are received, but generally ranges from three to six months.
Maintenance phase – This begins once the effective therapeutic dose is reached. The effective maintenance dose depends on your level of allergen sensitivity and your response to the immunotherapy build-up phase. During the maintenance phase, there will be longer periods of time between immunotherapy treatments, ranging from two to four weeks. Your allergist/immunologist will decide what range is best for you.
You may notice a decrease in symptoms during the build-up phase, but it may take as long as 12 months on the maintenance dose to notice an improvement. The effectiveness of immunotherapy treatments appears to be related to how long the treatment lasts, as well as the dose of the allergen. If you have not seen improvement after a year of maintenance therapy, work with your allergist/immunologist to determine possible reasons treatment failed and to discuss other treatment options.
Failure to respond to immunotherapy may be due to several factors such as:
- Inadequate dose of allergen in the allergy vaccine
- Missing allergens not identified during the allergy evaluation
- High levels of allergen in the environment (i.e. inadequate environmental control)
- Significant exposure to non-allergic triggers (i.e. tobacco smoke)
If immunotherapy is successful, maintenance treatment is generally continued for three to five years. The decisions to stop immunotherapy should be discussed with your allergist/immunologist because some patients may experience lasting remission of their allergy symptoms, while other individuals may relapse after discontinuing immunotherapy.
Are there risks?
Adverse reactions to immunotherapy are rare but do require immediate medical attention, which is why immunotherapy should be administered in a medical facility appropriately outfitted with equipment and staff capable of identifying and treating these reactions. There are two types of adverse reactions that can occur with immunotherapy:
Local reactions – These are fairly common reactions that include redness and swelling at the injection site. This can happen immediately or several hours after the treatment.
Systemic reactions – These are much less common than local reactions. Symptoms can include increased allergy symptoms such as sneezing, nasal congestion or hives. Rarely, a serious systemic reaction, called anaphylaxis, can develop after an immunotherapy injection. In addition to the symptoms associated with a mild systemic reaction, symptoms of an anaphylactic reaction can include swelling in the throat, wheezing or tightness in the chest, nausea and dizziness.
Most serious systemic reactions develop within 30 minutes of the allergy injections and will require immediate treatment. This is why it is recommended you wait in the office for at least 30 minutes after you receive immunotherapy.
(Adapted from AAAAI Topic of the Month – January – The importance of immunotherapy)