Although allergy shots have been used for many years, immunotherapy for symptoms of allergic rhinitis has only recently been clearly shown to be effective. Standardization of allergens will provide even better results in the diagnosis and treatment of allergic rhinitis in the future. Success in an individual patient depends on appropriate application. Immunotherapy should be reserved for patients who have allergy to airborne allergens, have significant symptoms after exposure to them, have sensitivity that has been proven by a skin or in vitro test, and cannot avoid the allergen or control symptoms with drugs. Thus, allergy shots are generally not used for allergy to pet dander or food. Immunotherapy is begun with a very dilute concentration of allergen, which is gradually increased to the maximum dose that is safely tolerated. The interval between shots is then increased gradually to once a month. Duration of treatment is usually 3 years in children and longer in adults. Treatment usually fails if the patient cannot free the environment of large amounts of known allergens, if the allergen was not correctly determined during initial evaluation, or if the allergen dose is inadequate. The patient must have realistic expectations: Allergy shots often do not totally eliminate symptoms, and improvement takes time.