What is immunotherapy?

Immunotherapy targets a specific allergen and works to change the process that causes symptoms in the first place rather than treating the symptoms themselves. It can be very effective, providing long-term relief for years after treatment has stopped, and it may also prevent the development of new allergies. Here's how it's done:

By gradually and repeatedly exposing a person to an allergen through injections (subcutaneous) or drops placed under the tongue (sublingual), the body's immune system begins to tolerate the substance and, over time, reduces its extreme response. (Note: Sublingual therapy is used extensively outside of the United States but has not yet been approved by the Food and Drug Administration [FDA] for use in America.)

Typically, immunotherapy shots are given once or twice a week by a specialist in allergen immunotherapy until an effective dose is achieved; then, the shots are given less frequently. It may take up to a year for symptoms to improve, and treatment generally continues for 3-5 years.

Immunotherapy is recommended for people who have moderate to severe allergy symptoms, have had a specific immunoglobulin E (IgE) antibody identified in their blood, and have not experienced sufficient relief from medications or cannot tolerate medications. Unfortunately, while immunotherapy works well for some people, it may not work at all for others.

Side effects include swelling or hardening at the injection site, itchy mouth (with sublingual therapy), difficulty breathing, and, in rare cases, anaphylactic shock.

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Immunotherapy, often called "allergy shots," aims to desensitize the patient to the triggering allergen by gradually increasing exposure over a period of time. Allergists recommend this treatment only for allergic rhinitis and conjunctivitis, allergic asthma, and insect venom allergies. Immunotherapy doesn't work for food allergies. Indeed, the primary treatment for food allergies is not to eat the food that triggers the reaction.