There are three basic methods for the treatment of
all allergic diseases including bronchial asthma. Theses are:
-
environmental control — or allergen avoidance,
-
drug therapy, and,
-
immunotherapy.
Most physicians will emphasize allergen avoidance and the use of inhaled medications as the first line treatment for asthma. In some cases, these treatments are only partially effective and allergy immunotherapy becomes necessary.
Allergy immunotherapy should is indicated in patients when the amount of medication a patient must take is so excessive that it becomes a burden, when the patient is not responding medication as expected, or if there are significant side effects from the medication.
Allergy immunotherapy involves the injection of the "allergen" to which the patient is sensitive. The injections are designed to alter the patient’s immune system so that they no longer react to the allergen. The mechanism by which immunotherapy works is not known. However, it has been demonstrated to be effective for both allergic rhinitis and asthma. There is also some evidence (although not clear) that it may help a subgroup of patients with eczema. Immunotherapy for pollens, cats, house dust mites and molds have all been studied, and injection of each of these allergens has been shown to completely or partially decrease the patient’s sensitivity and thus decrease their symptoms.
For the asthmatic patient, immunotherapy decreases inflammation in the lungs resulting in fewer symptoms and reduced need for asthma medications.
In practice, when immunotherapy is started, injections are given once or twice a week. Over a period of months, the dose of allergen is increased until a maintenance level of allergen is achieved. The frequency of injections is then decreased to once a month. The change in the immune system seen with immunotherapy takes place over a prolonged period of time. Thus, it may take several months of injections before any improvement is noticed, and the full benefit may not be realized for 6 months or more. If no improvement is seen after two allergy seasons using adequate immunotherapy doses, then the treatment should be stopped. If there is improvement, then the injections should be continued for at least 3 to 5 years (this may allow patients to have a prolonged benefit even after stopping the injections).
Most patients will have little or no side effects from immunotherapy. However, life-threatening reactions to immunotherapy can occur. Thus, allergy immunotherapy should only be administered in a physician’s office where trained personnel and cardiopulmonary resuscitation equipment are available and are observed after the injections to monitor for any side effects.
Immunotherapy should not be started during
pregnancy but it may be continued during pregnancy as long as there are
no symptomatic reactions.