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 dyspnea, 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.