chills

Chills are episodes of perceived coldness accompanied by shivering and gooseflesh, often occurring as part of the body's response to fever or cold exposure. They describe both the sensation of cold and the involuntary muscle activity that generates heat.

Physiologically, chills arise when the hypothalamus raises the body's temperature set point in response to pyrogens from infection, inflammation, or other sources. To reach the higher set point, the body constricts blood vessels and increases muscle activity through shivering.

Common causes include infections such as influenza, pneumonia, or urinary tract infections, but chills can also accompany noninfectious illnesses, medications or withdrawal, dehydration, hypoglycemia, or exposure to cold environments.

Chills often accompany fever but can occur without fever in cold surroundings or as a rapid temperature change. They may be followed by sweating, fatigue, body aches, or malaise.

Evaluation focuses on identifying the underlying cause. A clinician may measure temperature, perform a physical exam, and order tests as indicated. Management targets the cause and comfort: fever-reducing medicines, rehydration, and keeping warm; seek urgent care for severe or persistent symptoms, confusion, chest pain, stiff neck, or signs of sepsis.