Merck Manual

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Quick Facts

Hypothermia

By

The Manual's Editorial Staff

Last full review/revision Mar 2019
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What is hypothermia?

"Hypo" means low. "Thermia" has to do with temperature. So hypothermia is dangerously low body temperature, usually below 95° F (35° C).

  • You get hypothermia when you're in a cold place for a long time

  • Hypothermia is more likely if it's windy, you're in cold water or wet, or you can't move around to keep warm

  • At first, hypothermia makes you shiver

  • As hypothermia gets worse, you become confused and lose awareness

  • People may die if their body temperature gets below 88° F (about 28° C)

  • Babies and older people are at the greatest risk of hypothermia

See a doctor right away if you think you have hypothermia.

What causes hypothermia?

Hypothermia is caused by being in a cold place and not being able to warm your body.

You have a higher risk of getting hypothermia if you’re in a cold place and you:

  • Don't move your body (for example, you're injured or passed out from drinking alcohol)

  • Have certain health problems, such as infection, poor blood circulation, or hypothyroidism

  • Are very old or very young

It doesn't have to be really cold. You can get hypothermia even when it's only as cold as 55 or 60° F (about 13 to 16° C).

What are the symptoms of hypothermia?

At first you shiver a lot and your teeth chatter.

As hypothermia gets worse, you may also:

  • Become slow and clumsy

  • Be confused and respond slowly

  • Have slow reactions

  • Lose good judgment

  • Fall, lie down to rest, or wander

  • Stop shivering and slip into a coma

Eventually, your heart stops (cardiac arrest) and you die. However, you need less oxygen when you're really hypothermic. So some hypothermic people, particularly children, can live after being in cardiac arrest for up to an hour.

How can doctors tell if I have hypothermia?

Doctors tell you have hypothermia by checking your temperature. If your temperature is less than 95° F (35° C), you have hypothermia.

How do doctors treat hypothermia?

Anyone who's hypothermic should:

  • Take off wet clothes and dry off

  • Put on plenty of warm, dry clothes and a hat and cover up with a warm blanket

  • Drink something warm

If you're awake and just cold and shivering, this will warm you up eventually. If you seem confused or sluggish, someone should take you to a hospital. Doctors may have to do special warming treatments.

In a hospital, doctors may warm your body with the following:

  • Give you warm oxygen to breathe

  • Pump warm fluids into your veins through an IV or into your belly through a tube

  • Sometimes, warm your blood through a machine that pumps your blood out of your body, warms it, and pumps it back in

Don't give CPR to someone with hypothermia, because it could damage the person's heart. Just call 911 so the person can be brought to the hospital right away.

How can I prevent hypothermia?

You can prevent hypothermia in cold places by

  • Wearing a hat

  • Staying dry

  • Having layers of clothes that you take off or put on to keep warm but not get sweaty and wet

Older people get hypothermia more easily, so they should:

  • Keep their home at least 68° F (20° C), especially in the bedroom

  • Wear several layers of clothing, and make sure to cover their head, fingers, and toes in cold weather

  • Wear clothes made of wool and other insulated materials

  • Eat warm foods and drink warm fluids (but not alcohol) when they're in cold places

  • Walk around when they feel cold, to help warm the body

If you can’t afford to keep your home warm enough, look for fuel assistance programs in your area to get help with these costs.

NOTE: This is the Consumer Version. DOCTORS: Click here for the Professional Version
Click here for the Professional Version
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