Shivering

Shivering is an involuntary, rhythmic shaking of the body caused by rapid muscle contractions. It is a reflex response that helps generate heat when the body's core temperature falls, or it can accompany fever, illness, or other medical conditions. Shivering can also occur as a side effect of certain medications or procedures.

Mechanism and triggers: Shivering is coordinated by the hypothalamus, the body’s temperature-regulating center. When core temperature drops, the hypothalamus initiates muscle contractions to produce heat and constricts skin blood vessels to reduce heat loss. Shivering may accompany fever as the body responds to infection or inflammation; it can also occur with hypoglycemia, intoxication, panic, or exposure to cold environments.

Clinical features: Shivering usually involves rapid, alternating muscle movements that are visible in the arms, legs, and torso. It may be accompanied by chills, sweating, rapid breathing, anxiety, or confusion, depending on the underlying cause and the person’s age and health.

Diagnosis and treatment: Evaluation focuses on identifying the underlying cause, such as environmental cold, fever, infection, dehydration, or hypothermia. For mild cold exposure, passive warming (moving to a warm environment, removing wet clothing) and insulating, dry clothing is often sufficient. Fever-related shivering may respond to fever-reducing medications. Treating the underlying condition is essential. Severe shivering or shivering with suspected hypothermia, chest pain, or altered mental status warrants medical care.

Prevention and prognosis: Adequate clothing for cold weather, gradual acclimatization, and prompt treatment of fever or infection reduce shivering risk. Most shivering resolves with warming or treatment of the underlying cause; persistent or recurrent shivering should be evaluated by a clinician.