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What Is Allergen Immunotherapy?
The American Academy of Family Physicians defines allergen immunotherapy as “the administration of gradually increasing quantities of specific allergens to patients with IgE-mediated conditions until a dose is reached that is effective in reducing disease severity from natural exposure.” This allergy treatment option is also known as allergen-specific immunotherapy, allergy vaccine therapy, hyposensitization therapy or immunologic desensitization.
The basic objective of this type of treatment is to decrease the reaction triggered by allergens and to prevent (long-term) the recurrence of the disease. Allergen immunotherapy has shown to be very effective for allergic reactions to insect bites and stings, pollen (allergic rhinitis), allergic conjunctivitis, and allergy related asthma attacks. Allergen-specific immunotherapy is the only therapy known to alter the allergic disease. Other treatments (antihistamines, corticoids) just temporarily suppress the reactions, signs and symptoms of the diseases. In some instances a total cure is possible with allergy vaccine therapy.
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How Does Allergen Immunotherapy Work?
After the allergy have been established by skin testing, an allergist will use extracts of known allergens (for example, grass, tree pollen, mites, molds, insect venom) for allergy immunotherapy. Allergy vaccine therapy is based on subcutaneous injections of specific allergens.
The allergen concentration injected into the patient is increased gradually. At first, the patient receives very low quantities, and as tolerance is built up, the injected concentration is increased. Six months into the treatment enough tolerance has been developed by the patient so that he can start to see a decreased reaction to the allergen. At this point a maintenance dose has been reached. The patient continues to receive the maintenance dose every two to four weeks for the next four to six months. After a year, the allergist will evaluate the effectiveness of the therapy. If allergic symptoms and signs have improved, then the immunotherapy is continued for up to three to five years. If not, the the vaccines shots are discontinued.
In rush immunotherapy (also called accelerated immunotherapy), the allergen concentration is increased very quickly by giving the patient very frequent (every one hour, for example) allergen shots. The maintenance dose is achieved within a week (instead of six months in traditional immunotherapy). Rush immunotherapy is riskier than traditional allergen immunotherapy.
Sublingual immunotherapy involves taking sublingual drops or pills instead of shots. This allergy treatment is widely used in Europe, but not approved in the United States. Many studies have shown that sublingual immunotherapy is very effective in treating allergies, especially when high allergen doses are used.
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Huggins, J. L., Looney, J. (2004). "Allergen Immunotherapy," Am Fam Physician. 70(4): 689-696. http://www.aafp.org/afp/2004/0815/p689.html
Web MD: "Rush immunotherapy for allergies," http://www.webmd.com/hw-popup/rush-immunotherapy-for-allergies
Smith et. al. 2004. "Randomized controlled trial of high-dose sublingual immunotherapy to treat seasonal allergic rhinitis." J. Allergy Clin. Immunol. 114 (4): 831–7