Hypothermia

Hypothermia occurs when the body gets cold and loses heat faster than the body can make it. A normal rectal body temperature ranges from 97.5°F (36.4°C) to 99.7°F (37.6°C) and for most people is 98.6°F (37°C) by mouth and 99.7°F (37.6°C) rectally. Hypothermia is more likely to occur when you are exposed to cold air, water, wind, or rain. Hypothermia can occur indoors, especially in babies and older or ill adults that are not dressed warmly enough.

A rectal temperature is considered the most accurate body temperature. For information on how to take an accurate temperature, see the topic Body Temperature.

Emergency care needed

Hypothermia is an emergency condition and can quickly lead to unconsciousness and death. Hypothermia can occur at temperatures of 50°F (10°C) or higher in wet and windy weather, or if you are in 60°F (16°C) to 70°F (21°C) water.

Severity

• Mild hypothermia: Rectal temperatures between 90°F (32°C) and 95°F (35°C)
• Moderate to severe hypothermia: Rectal temperatures below 90°F (32°C)

Early symptoms

• Shivering
• Cold, pale, or blue-gray skin
• Lack of interest or concern (apathy)
• Poor judgment
• Mild unsteadiness in balance or walking
• Slurred speech
• Numb hands and fingers and difficulty performing tasks

Late symptoms

• The trunk of the body is cold to the touch.
• Muscles become stiff.
• Slow pulse
• Breathing is shallow and slower.
• Weakness or sleepiness
• Confusion
• Loss of consciousness
• Shivering may stop if body temperature drops below 90°F (32°C).

Medical treatment

It is very important to get treatment for hypothermia quickly. Often a hiker or skier's body temperature will drop really low before others notice something is wrong. If someone begins to shiver violently, stumble, or can't respond to questions, suspect hypothermia and warm them quickly.

Medical treatment for hypothermia depends on the severity of the hypothermia. Treatment of mild hypothermia includes getting out of the cold or wet environment, using warm blankets, heaters, and hot water bottles.

Moderate to severe hypothermia generally is treated in the hospital, where doctors can give warmed intravenous fluids and warm, moist oxygen in addition to other treatments to warm the core body temperature.

Most healthy people with mild to moderate hypothermia recover completely without permanent injury. Recovery is harder for babies and older, ill, or inactive adults.