A "code blue" is a hospital emergency code used to describe the critical status of a patient. It is part of an emergency code system, and different colors or terms mean different things. In most hospitals, a "code blue" means that someone is experiencing a life-threatening medical emergency, usually cardiac or respiratory arrest. The code indicates that the sick person cannot be moved, and the announcement may include warning sounds and a location.

When a "code blue" is called, a team of healthcare providers who are trained in advanced cardiac life support or in resuscitating patients will respond to the emergency. The team may also include specialists like an anesthesiologist or internal medicine doctor. The hospitals response to a "code blue" call varies depending on the patients condition.

Emergency color codes can differ across regions or hospitals, as some facilities specifically use "code blue" for cardiac arrest, and in some states, the code applies only to adults. However, wherever you are, "code blue" alerts the hospital that a patient needs nurses and doctors as soon as possible. Other hospital emergency codes include "code purple" for emergencies in children, "code white" for pediatric medical emergencies, and codes for fire, the need for decontamination, and more.