Immunotherapy is a preventive treatment for allergic reactions to substances such as grass pollens, house dust mites, and bee venom. It involves giving gradually increasing doses of the substance, or allergen, to which the person is allergic. The incremental increases of the allergen cause the immune system to become less sensitive to the substance, probably by causing production of a “blocking” antibody, which reduces the symptoms of allergy when the substance is encountered in the future. Immunotherapy also reduces the inflammation that characterizes rhinitis and asthma.

Allergy shots, also known as subcutaneous immunotherapy (SCIT), are the most commonly used and most effective form of allergy immunotherapy). This is the only treatment available that actually changes the immune system, making it possible to prevent the development of new allergies and asthma). Sublingual (under the tongue) immunotherapy is an alternative way to treat allergies without injections. The only FDA-approved sublingual therapy is tablets. Allergy drops are not FDA-approved and are off-label in the United States.

Allergy shots work like a vaccine. Your body responds to injected amounts of a particular allergen, given in gradually increasing doses, by developing immunity or tolerance to the allergen). There are two phases:

• 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 phase involves receiving injections with the same dose of allergen at longer intervals, typically every two to four weeks, for a period of three to five years or longer).

Immunotherapy can provide long-term symptom relief for years after treatment is discontinued, and it is a cost-effective approach to treating allergies. It may also help prevent new allergies and stop the progression of allergic diseases, from allergic rhinitis (hay fever) to eczema and asthma. Food allergy immunotherapy is used to build up a tolerance for small quantities of a food allergen, and it is a treatment, not a cure, for food allergy. The type of immunotherapy options available for you depends on the specific allergen.