Hypothermia

What is hypothermia?

Hypothermia, or low body temperature, is a condition that occurs when your body’s temperature drops below 95 degrees Fahrenheit (35 degrees Celsius). The average normal body temperature is 98.6 F (37 C). Hypothermia is a medical emergency.

When your body temperature is dangerously low, your brain and body can’t function properly. Left untreated, hypothermia can lead to cardiac arrest (when your heart stops beating) and death.

How common is hypothermia?

Mild, treatable cases of hypothermia are more common, especially among groups of people who are at risk. In the United States, between 700 and 1,500 people die every year from hypothermia.

What are the symptoms of hypothermia?

Hypothermia symptoms vary based on the severity of the condition. The stages of hypothermia include mild, moderate and severe.

Mild hypothermia

Mild hypothermia means your body temperature is between 95 F and 89.6 F (35 C and 32 C). Signs of mild hypothermia include:

• Shivering and chattering teeth.
• Exhaustion.
• Clumsiness, slow movements and reactions.
• Sleepiness.
• Weak pulse.
• Fast heart rate (tachycardia).
• Rapid breathing (tachypnea).
• Pale skin color.
• Confusion and poor judgment/loss of awareness.
• Excessive urination.
• Trouble speaking.

Moderate hypothermia

Moderate hypothermia means your body temperature is between 89.6 F and 82.4 F (32 C and 28 C). Signs of moderate hypothermia include:

• Slow down in breathing and heart rate.
• Slurred speech.
• Decline in mental function.
• Hallucinations.
• Decreased shivering.
• Bluish color to skin (cyanosis).
• Increased muscle stiffness.
• Dilated pupils.
• Abnormal heart rhythm.
• Decreased blood pressure.
• Weakened reflexes.
• Loss of consciousness.

Severe hypothermia

Severe hypothermia means your body temperature is less than 82.4 F (28 C). Signs of severe hypothermia include:

• Loss of shivering.
• Low blood pressure (hypotension).
• Fluid in lungs.
• Absence of reflexes.
• Complete muscle stiffness.
• Loss of voluntary motion.
• Low urine output (oliguria).
• Heart stops beating (cardiac arrest).
• Coma that may mimic death.
• Death.

What causes low body temperature (hypothermia)?

Hypothermia occurs after exposure to cold, wet or windy conditions. When you’re exposed to cold, your body expends energy to keep you warm. Eventually, with continued exposure to cold temperatures, your body uses up its stored energy and your body temperature begins to fall. You’re not able to warm yourself back up. Symptoms will progress from mild to severe with prolonged exposure.

While most cases of hypothermia occur at very cold temperatures, the condition can affect you even in cooler temperatures over 40 F (4.4 C) if you become chilled from sweat, rain or submersion in cold water. Hypothermia occurs under environmental conditions (wet, cool/cold or windy) that cause a person’s body to lose more heat than it generates.

Who is at risk for developing hypothermia?

Although anyone can get hypothermia, certain people, conditions and situations increase the risk of developing hypothermia. These include:

• Older people. The ability to control body temperature lessens with age. Older people also tend to expend less energy (which generates heat to keep your body warm) because they’re less active than younger people. Older people tend to have less fat to provide insulation as well.
• Young children. Children use more calories (energy) than adults and may use up their reserve while playing and not realize they’re cold. Children have more surface area for their size, which increases their heat loss.
• Babies. Infants lose body heat more easily than adults, don’t have the energy reserve to shiver to increase their body heat and can even become hypothermic if they sleep in a cold room. Signs of hypothermia in an infant include cold skin, bright red skin, inactivity/lack of energy and body temperature under 95 F (35 C). Babies have the highest surface area for their weight and lose heat the most rapidly.
• Inexperienced outdoor adventure seekers. This includes hikers, hunters and fishers who don’t have appropriate gear for the cold and wet conditions they may encounter.
• People who abuse alcohol or recreational drugs. Alcohol expands blood vessels, allowing heat to leave your skin surface more rapidly. Alcohol, as well as drug use, can impair a person’s ability to feel cold and/or not have good judgment about wearing appropriate clothing to match the weather conditions or coming inside when cold.
• People who don’t have a home. People without a place to live may not have or not choose indoor shelter options with heat. They also may not have clothing appropriate for the weather conditions.
• People with mental health conditions. People who have dementia or other intellectual impairment may lack the ability to judge weather conditions, may wander away from home and get lost, and may not wear appropriate clothing to stay warm for an extended time in cold weather.
• People with certain medical conditions may be more susceptible to cold temperatures. These conditions include hypothyroidism, hypoglycemia, hypopituitarism, shock, sepsis, anorexia nervosa, stroke, Parkinson’s disease, peripheral neuropathy and spinal cord injury.
• People taking certain medications. Medications that can impair your response to cold include sedatives, anesthetics, opioids, phenothiazine antipsychotics and clonidine.
• People participating in cold-weather sports. Sports like skiing often occur at low temperatures and happen in areas with unpredictable weather patterns. The activity level pre-disposes heat loss due to the activity involved and sweating. These sports can also expose participants to injury, and in severe instances, can lead to altered decision-making.

What are the complications associated with hypothermia?

If left untreated, hypothermia can lead to various medical conditions, including:

• Cardiac arrest.
• Liver damage.
• Kidney failure.
• Coma.
• Death.

How is hypothermia diagnosed?

Healthcare providers diagnose hypothermia by taking your temperature and checking your symptoms. Based on your symptoms and how low your body temperature is below 95 F (35 C), they’ll diagnose you with mild, moderate or severe hypothermia.

How do you treat hypothermia?

Hypothermia treatment includes the prevention of further heat loss and the process of rewarming. If you’re with someone who has hypothermia, call for help and then take the following steps:

• Move the person to a warm, dry location.
• Remove wet clothing and replace with dry clothing.
• Cover them up with a jacket, hat and blanket.
• Apply external heat to their skin, such as with a heat lamp or hot pack.

When hypothermia is more severe, healthcare providers may also need to:

• Insert an IV into your vein and pump warm fluids into your body.
• Give you warm oxygen through a mask or breathing tube.
• Use a machine that warms your blood and pumps it back into your body.

Can hypothermia be prevented?

When it’s cold, you should wear a hat that covers your ears and warm, dry clothing. Older people and children should take extra care to prevent hypothermia by:

• Dressing in layers and keeping warm clothes nearby.
• Keeping homes at a temperature above 68 F (20 C).
• Moving around when you feel cold so you can increase your body temperature.
• Eating and drinking warm foods and beverages.
• Wearing appropriate clothing outdoors, including hats, mittens, coats and footwear.
• Taking regular breaks and coming inside to warm up whenever spending time outside.
• Avoid substances known to contribute to hypothermia, such as alcohol or certain medications.

What can I expect if I have hypothermia?

If you experience mild hypothermia with no cardiac issues and receive treatment in a timely manner, you should be able to recover with no long-term problems close to 100% of the time. The mortality rate of people with moderate to severe hypothermia drops to 50% even with supportive in-hospital care.

What can I do to help relieve symptoms of hypothermia?

If you or someone you know has symptoms of hypothermia, you should get medical help immediately. In the meantime, you should:

• Get somewhere warm and dry.
• Take off wet clothes and replace with dry clothes.
• Wrap up in a warm blanket, hat, socks and coat.
• Drink warm liquids.

When should I see my healthcare provider?

Hypothermia is an emergency. You should get medical help right away if you or someone you know has symptoms of hypothermia. Left untreated, hypothermia can be fatal.

When should I go to the ER?

If you have symptoms of hypothermia and a low body temperature, you should call 911 or go to the emergency room immediately. Hypothermia is a medical emergency and should be treated as soon as possible.

What questions should I ask my healthcare provider?

Questions you may want to ask a healthcare provider about hypothermia include:

• How can I prevent hypothermia in the future?
• How long can a person stay outdoors before hypothermia sets in?
• Are there any long-term complications of hypothermia I need to worry about?

Hypothermia vs. hyperthermia — what’s the difference?

Hypothermia occurs when your body temperature drops below 95 F (35 C) and you can’t rewarm yourself. Hyperthermia is the opposite. It occurs when you have an abnormally high body temperature, or when you’re overheating. A body temperature above about 100 F (37.8 C) is too warm. Hyperthermia happens when your body generates or is exposed to more heat than it can release.

A note from Cleveland Clinic

You’re shivering. Your teeth are chattering. You’re starting to get sleepy. The signs of hypothermia can come on slowly. While you may not realize it, you need to get help right away. Hypothermia can affect your thinking, which makes the condition even more dangerous. If you or someone you’re with are experiencing any of the signs and symptoms of hypothermia, seek help immediately. It’s a medical emergency that can be fatal if you don’t seek treatment right away. Hypothermia should always be thought about and considered before you or a loved one spend any significant time in cold environments.