Allergy Shots (Allergen Immunotherapy)

What Is It?

Allergy shots are a treatment that can help to prevent or minimize allergic reactions. They are personalized to each patient—the shots are only useful when specific allergy triggers have been identified. Allergy shots are received on a schedule, over a period of several years.

What It's Used For

Common allergic symptoms are sneezing, runny nose, itchy eyes or asthma attacks. Allergy symptoms are caused by your body's reaction to a substance (allergen) that is inhaled, touched or eaten. Allergens cause no symptoms in a non-allergic person, but in an allergic person who is sensitized to that antigen, an immune reaction against the allergen causes symptoms.

In allergy, the body responds to the allergen in the same way it would respond to fight off infection by a parasite. The immune system recognizes the substance as foreign and activates an army of antibodies to eliminate the invader. The antibodies bind with the allergen and then trigger immune system cells to release chemicals, such as histamine. This release of histamine is what causes most allergy symptoms.

To continue reading this article, you must login.
  • Research health conditions
  • Check your symptoms
  • Prepare for a doctor's visit or test
  • Find the best treatments and procedures for you
  • Explore options for better nutrition and exercise
Learn more about the many benefits and features of joining Harvard Health Online »