Internal medicine is the medical specialty dealing with the prevention, diagnosis, and treatment of adult diseases. Doctors of Internal Medicine, also known as internists, are sometimes referred to as the "doctor's doctor," because they are often called upon to act as consultants by other physicians to help solve puzzling diagnostic problems. They are especially skilled in the management of patients who have undifferentiated or multi-system disease processes. An internist cares for hospitalized and ambulatory patients and may play a major role in teaching or research. Internal medicine is also a type of veterinary specialty.
The term internal medicine comes from the German term innere Medizin, popularized in Germany in the late 19th century to describe physicians who combined the science of the laboratory with the care of patients. Many early-20th-century American doctors studied medicine in Germany and brought this medical field to the United States. Thus, the name "internal medicine" was adopted in imitation of the existing German term. Specialists in internal medicine are commonly called internists in the United States.