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March 27, 2018


JAMA. 2018;319(12):1290. doi:10.1001/jama.2018.0749

Hypothermia is a medical emergency; it occurs when a person is exposed to excessive cold temperatures.

Hypothermia is defined by a core body temperature lower than 35°C (95°F). Below this temperature, the body loses more heat than it generates.

Acute hypothermia occurs with immersion in cold water or exposure to cold weather. Chronic hypothermia occurs with certain diseases, aging, or prolonged exposure to cold temperatures. People with chronic illnesses, such as diabetes, arthritis, and preexisting heart conditions, as well as homeless persons, elderly persons, and young children are more prone to developing hypothermia.

Hypothermia causes major dysfunction in vital organs such as the heart, leading to irregular heartbeat; the kidneys, leading to kidney failure; and the brain, leading to mental status changes such as confusion or loss of consciousness. Liver damage, bleeding disorders, and breakdown of muscle tissue can also occur. Damage occurs when the mechanisms of heat regulation start to fail as the body temperature continues to drop.


  • Check the weather forecast before going outdoors and plan accordingly.

  • Wear multiple layers of clothing, a hat, and a scarf to minimize heat loss.

  • At home, set the thermostat to 68°F or higher.

  • Dress warmly if the temperature is cold indoors.

  • To reduce heating costs, make sure all doors and windows are tightly closed. Place rolled towels underneath doors to prevent drafts. Open curtains during the day to allow sunlight in; close them at night.

  • Space heaters can be used as a supplementary heat source. Keep heaters 3 ft away from flammable items. Plug directly into a wall outlet and never leave unattended. Do not use unvented gas heaters indoors because of risk of carbon monoxide poisoning. Ensure smoke and carbon monoxide detector alarms are working.

  • Avoid use of alcohol or caffeinated beverages—these increase heat loss.

  • Ensure babies have proper clothing and limit their exposure to cold temperatures.

  • Check on elderly persons and neighbors living alone and ensure they have adequate food, clothing, and heating.

What to Do in Case of Hypothermia

In adults, look for shivering, pallor, and drowsiness. In infants, look for bright red, cold skin and a low energy level. If you see symptoms of hypothermia, consider calling 911 immediately. Goals include preventing further heat loss and rewarming the affected individual.

  • Move affected person into a warm building. Be gentle and avoid rubbing or massaging the skin.

  • Remove any wet clothing and cover the person with dry or warm blankets.

  • Do not use direct heat like a heating pad or hot bath to warm the person. The heat may cause burns, and the person’s core temperature may drop even further.

  • If the affected person is conscious, provide a warm beverage. Avoid alcohol or caffeine.

If hypothermia progresses to a severe state, the individual may become unresponsive and cardiopulmonary resuscitation (CPR) may be needed until emergency personnel arrive.

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Conflict of Interest Disclosures: All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest and none were reported.

Sources: Centers for Disease Control and Prevention. Hypothermia-related deaths—United States, 2003. MMWR Morb Mortal Wkly Rep. 2004;53(8):172.