Internal medicine or general medicine (in Commonwealth nations) is the medical specialty dealing with the prevention, diagnosis, and treatment of adult diseases. Physicians specializing in internal medicine are called internists, or physicians (without a modifier) in Commonwealth nations. Internists are skilled in the management of patients who have undifferentiated or multi-system disease processes. Internists care for hospitalized and ambulatory patients and may play a major role in teaching and research.
Because internal medicine patients are often seriously ill or require complex investigations, internists do much of their work in hospitals. Internists often have subspecialty interests in diseases affecting particular organs or organ systems.
Internal medicine is also a specialty within clinical pharmacy and veterinary medicine.
Historically, some of the oldest traces of internal medicine can be traced from Ancient India and Ancient China. Earliest texts about internal medicine are the Ayurvedic anthologies of Charaka.
Internal medicine physicians have practiced both in clinics and in hospitals, often in the same day. Pressures on time have led to many internal medicine physicians to choose one practice setting, who may choose to practice only in the hospital, as a "hospitalist", or only in an outpatient clinic, as a primary care physician.
The term internal medicine originates 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 physicians 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.
Much confusion surrounds the meaning of internal medicine and the role of an "internist." Internists are qualified physicians with postgraduate training in internal medicine and should not be confused with "interns", who are doctors in their first year of residency training (officially the term intern is no longer in use). Although internists may act as primary care physicians, they are not "family physicians," "family practitioners," or "general practitioners," whose training is not solely concentrated on adults and may include surgery, obstetrics, and pediatrics. The American College of Physicians defines internists as "physicians who specialize in the prevention, detection and treatment of illnesses in adults".