In the Chinese healthcare system, the patient experience differs significantly from many Western countries. While in the U.S. or U.K. one might first visit a General Practitioner (GP) or family doctor who then provides a referral to a specialist, in China, patients often go directly to a hospital for almost all medical needs. This makes 内科 (nèikē) the de facto “front door” for a vast number of patient visits. When you arrive at a hospital and need to register (挂号 - guàhào), you are expected to choose the department you need. If you have an undiagnosed illness that isn't an emergency and doesn't obviously require surgery (like a broken bone), 内科 is the standard, correct choice. It's also important to distinguish this from Traditional Chinese Medicine (TCM). 内科 refers specifically to modern, Western-style medicine. The TCM equivalent would be 中医内科 (zhōngyī nèikē), which uses entirely different diagnostic methods and treatments like herbal medicine and acupuncture. In a large hospital, these will be two completely separate departments.
You will encounter and use the term 内科 in very specific, practical situations, primarily when seeking medical care.
The term is neutral and has a standard, formal-to-neutral connotation, used exclusively in medical contexts.