Allergenic immunotherapy consists of repeated administration of allergenic extracts to which an individual is allergic. It is currently the only treatment that modifies the course of allergic disease and induces short- as well as long-term remission of symptoms. Two formulations are currently available: subcutaneous immunotherapy (SCIT) or sublingual immunotherapy (SLIT), with comparable efficacy. In specific situations, it can be used in combination with the new approved biologic therapies for asthma to improve tolerance of immunotherapy.