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.
Internal medicine specialists, also known as general internal medicine specialists or general medicine physicians in Commonwealth countries, are specialist physicians trained to manage particularly complex or multisystem disease conditions that single-organ-disease specialists may not be trained to deal with. They may be asked to tackle undifferentiated presentations that cannot be easily fitted within the expertise of a single-organ specialty, such as dyspnoea, fatigue, weight loss, chest pain, confusion or change in conscious state. They may manage serious acute illnesses that affect multiple organ systems at the same time in a single patient, and they may manage multiple chronic diseases or "comorbidities" that a single patient may have.
Perhaps because it is complex to explain treatment of diseases that are not localised to a single-organ, there has been confusion about 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".
Following completion of entry-level training, newly graduated medical practitioners are often required to undertake a period of supervised practice before the licensure, or registration, is granted, typically one or two years. This period may be referred to as "internship", "conditional registration", or "foundation programme". Then, doctors may finally follow specialty training in internal medicine if they wish, typically being selected to training programs through competition. In North America, this period of postgraduate training is referred to as residency training, followed by an optional fellowship if the internist decides to train in a subspecialty. In Commonwealth countries, during that training period in internal medicine, trainees are often called senior house officers, and advance to registrar grade when they undergo a compulsory subspecialty training whilst commonly continuing service provision in the main speciality. In the United States, residency training for internal medicine lasts three years.
In the United Kingdom, the three medical Royal Colleges (the Royal College of Physicians of London, the Royal College of Physicians of Edinburgh and the Royal College of Physicians and Surgeons of Glasgow) are responsible for setting curricula and training programmes through the Joint Royal Colleges Postgraduate Training Board (JRCPTB), although the process is monitored and accredited by the General Medical Council (which also maintains the specialist register).
Many training programmes provide dual accreditation with general (internal) medicine and are involved in the general care to hospitalised patients. These are acute medicine, cardiology, Clinical Pharmacology and Therapeutics, endocrinology and diabetes mellitus, gastroenterology, infectious diseases, renal medicine, respiratory medicine and often, rheumatology. The role of general medicine, after a period of decline, was reemphasised by the Royal College of Physicians of London report from the Future Hospital Commission (2013).