Allergists and immunologists receive the same medical training, although they choose different specialties – allergists focus strictly on allergies, while immunologists can diagnose and treat allergies, but also work with patients who are suffering from autoimmune disorders. Both are medical doctors who have received extensive training in allergy and immunology upon completion of medical school and a residency in internal medicine or pediatrics. Immunologists may often be referred to as allergists, as allergies are caused when the immune system overreacts to exposure to an allergen. In addition to treating allergy patients, immunologists are also involved in conducting research to help understand and explain why the immune system sometimes malfunctions. They can work with patients of all ages in the evaluation and diagnosis of immune system disorders in order to help them manage their symptoms and treat the disorder. Patients who see an immunologist for the treatment of an autoimmune disorder will also typically work with additional specialists, such as a rheumatologist, depending on the type of autoimmune disorder.