Allergen Immunotherapy also known as allergy injections is a preventive treatment for allergic reactions to substances such as grass pollens, house dust mites, and bee venom. Immunotherapy 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.