Hypothermia (Low Body Temperature)

Overview

What is hypothermia?

Hypothermia is a condition that occurs when the body’s temperature drops below 95° F (35° C). Normal body temperature is 98.6° F (37° C). Hypothermia is a medical emergency.

When a person’s body temperature is dangerously low, the brain and body cannot function properly. Left untreated, hypothermia can lead to cardiac arrest (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, more than 1,300 people die every year from hypothermia.

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. Elderly also tend to expend less energy (which generates heat to keep the body warm) because they are less active than younger people. They may live in a house or other environment that is too cold.
  • Young children. Children use more calories (energy) than adults and may use up their reserve while playing and not even realize they are cold.
  • 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).
  • Inexperienced outdoor adventure seekers such as hikers, hunters, fishers who do not 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 the 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.
  • Homeless people. Homeless people 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 problems. 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 temperature. These conditions include hypothyroidism, hypoglycemia, hypopituitarism, shock, sepsis, anorexia nervosa, stroke, Parkinson’s disease, peripheral neuropathy, spinal cord injury.
  • Medications that can impair a person’s response to cold include sedatives, anesthetics, opioids, phenothiazine antipsychotics and clonidine

Symptoms and Causes

How do people get hypothermia?

Hypothermia occurs after exposure to cold, wet or windy conditions. When you are exposed to cold, your body expends energy to keep you warm. Eventually, with continued exposure to cold temperature, your body uses up its stored energy and your body temperature begins to fall.

It should be noted that hypothermia can occur in temperatures over 40° F. Hypothermia occurs under environmental conditions (wet, cool/cold, or windy) that cause a person’s body to lose more heat than it generates.

What are the symptoms of hypothermia?

Signs of mild hypothermia (95° F to 89.6° F // 35° C to 32° C) include:

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

Signs of moderate hypothermia (89.6° F to 82.4° F // 32° C to 28° C) include:

  • Slowdown in breathing and heart rate
  • Slurred speech
  • Decline in mental function
  • Loss of shivering
  • Bluish color to skin
  • Muscle stiffness
  • Dilated pupils
  • Abnormal heart rhythm
  • Decreased blood pressure
  • Weakened reflexes
  • Loss of consciousness

Signs of severe hypothermia (< 82.4° F // 28° C) include:

  • Low blood pressure
  • Fluid in lungs
  • Absence of reflexes
  • Low urine output
  • Heart stops beating (cardiac arrest)
  • Coma that may mimic death
  • Death

Diagnosis and Tests

How is hypothermia diagnosed?

Doctors diagnose hypothermia by taking your temperature and checking your symptoms. Based on your symptoms and how low your body temperature is below 95° F, you will be diagnosed with mild, moderate or severe hypothermia.

Management and Treatment

What are the treatments for hypothermia?

The first steps when treating hypothermia are:

  • Move to a warm, dry location
  • Remove wet clothing and replace with dry clothing
  • Cover up with a jacket, hat, and blanket

When hypothermia is more severe, doctors 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

What are the side effects of the treatment for hypothermia?

Hypothermia treatment has no side effects. If you are treated in the hospital, your doctor will monitor you to make sure your body temperature reaches a normal level.

What are the complications associated with hypothermia?

If left untreated, hypothermia can lead to cardiac arrest and death.

Prevention

How can you prevent hypothermia?

When it is cold, you should wear a hat that covers the 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
  • 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

Outlook / Prognosis

What is the outlook for patients who have hypothermia?

If they receive treatment in time, people with hypothermia usually recover with no long-term problems.

Living With

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 call my doctor about hypothermia?

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.

How do I know if I have hypothermia?

If you have symptoms of hypothermia and a low body temperature (under 95° F), you should contact your doctor right away, call 911 or go to the emergency room. Hypothermia is a medical emergency.

Last reviewed by a Cleveland Clinic medical professional on 08/12/2019.

References

  • Merck Manual. Accessed 7/2/2019. Hypothermia. (https://www.merckmanuals.com/home/quick-facts-injuries-and-poisoning/cold-injuries/hypothermia)
  • American Academy of Pediatrics. Accessed 7/2/2019.Cold Weather Safety. (https://www.healthychildren.org/English/safety-prevention/at-play/Pages/Cold-Weather-Safety.aspx)
  • Centers for Disease Control and Prevention. Accessed 7/2/2019.Prevent Hypothermia & Frostbite. (https://www.cdc.gov/disasters/winter/staysafe/hypothermia.html)
  • Cheshire W.P. JR. Autonomic Neurosci 2016;196(4):91-104.Thermoregulatory disorders and illness related to heat and cold stress. (https://www.sciencedirect.com/science/article/pii/S1566070216300017)

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