What are allergy shots (immunotherapy)?

Dr. Darria Long Gillespie, MD
Emergency Medicine
Allergy shots are a form of immunotherapy. Immunotherapy retrains the immune system to make you less sensitive to specific allergens. A series of injections is given, each having a small amount of the allergens that cause your symptoms. The amount of each allergen is gradually increased over time. Besides reducing symptoms, allergy shots can prevent new allergies and reduce the risk of asthma. This therapy is most effective for children and young adults. 

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Anthony L. Komaroff, MD
Internal Medicine
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.
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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Allergy shots (immunotherapy) are injections that contain small amounts of an antigen (a substance you are allergic to). They stimulate your immune system to create antibodies to block your allergic response. Basically, what this means is that your body will block the allergic reaction you have to the substance.
Clifford W. Bassett, MD
Allergy & Immunology

An allergy shot, or immunotherapy, is a vaccine that causes a state of tolerance and reduces allergy symptoms until they dissipate and go away. Watch allergist Clifford Bassett, MD, discuss the long-term health benefits of immunotherapy.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.