Condition Basics

What is hypothermia?

Hypothermia occurs when the body gets cold and loses heat faster than the body can make it.

A body temperature below normal can be a sign of hypothermia.

A rectal temperature is considered the most accurate body temperature. A normal rectal body temperature ranges from 36.4°C (97.5°F) to 37.6°C (99.6°F), and for most people it is 37°C (98.6°F).

What causes it?

Hypothermia can occur when you are exposed to cold air, water, wind, or rain.

Your body temperature can drop to a low level at temperatures of 10°C (50°F). Your body temperature can drop even if it is warmer than 10°C (50°F) if you are out in wet and windy weather. If you're in water that is 15°C (60°F) to 21°C (70°F), you are also at risk for hypothermia.

But hypothermia can occur indoors, especially in babies and older or ill adults who are not dressed warmly enough.

What are the symptoms?

Early symptoms of hypothermia include:

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

Late symptoms include:

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

How is hypothermia treated?

It is very important to know the symptoms of hypothermia and get treatment quickly. Often a hiker or skier's body temperature will drop really low before others notice that something is wrong. If someone begins to shiver violently, stumble, or can't respond to questions, it may be hypothermia. You need to quickly help the person get warm.

Sometimes a normal, healthy adult has a low body temperature, such as 36°C (96°F). If the person with the low body temperature is not ill, does not have any other problems, and is not an infant or an older adult, then evaluation usually is not needed.

Medical treatment for hypothermia depends on the severity of the hypothermia.

If you have mild hypothermia, home treatment may be enough to bring your body temperature back up to normal. 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 use special techniques to warm the core body temperature.

What increases your risk?

Anyone can get hypothermia. Very young children and older people can be at higher risk. This is because their bodies may not be able to control temperature as well. And some people have medical conditions or take medications that may increase their risk. People who spend lots of time outdoors may also increase their risk of hypothermia. This may happen when they are not dressed warmly enough and aren't prepared for colder temperatures.

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