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Hypothermia or hyperthermia?

Alice,

What are the symptoms of hypothermia or is it hyperthermia?

—Temperature change

Dear Temperature Change,

You’re hot, then you’re cold... that sound familiar? Hopefully not! Hypothermia and hyperthermia are two extreme, but equally concerning, states of abnormal thermoregulation, which refers to how the body maintains its internal temperature. Hypothermia occurs when you lose more heat than your body can produce and you feel very cold. Hyperthermia occurs when your body produces more heat than it can lose. The elderly are the most vulnerable to experiencing these conditions, as they have a reduced ability to adjust to colder or hotter temperatures.

Hypothermia occurs when your body temperature drops below 95 degrees Fahrenheit (35 degrees Celsius). Your body temperature may be lowered if you're exposed to cold temperatures or a cold, wet, windy environment for a long amount of time. Getting drenched in the rain or swimming on a cold, windy day, and not drying off, for example, may lead to hypothermia. However, hypothermia may also occur if you aren’t wearing enough warm clothing on a cold day. The following symptoms of hypothermia include:

  • Shivering
  • Confusion or memory loss
  • Trouble with coordination
  • Slurred speech
  • Slow and shallow breathing rate
  • Skin that is cold and pale
  • Weak pulse
  • Feeling fatigued or lethargic

List adapted from Hypothermia from Mayo Clinic.

Complications of hypothermia may include getting frostbite (and subsequent loss of limbs) or coma. If you or someone you know may be suffering from hypothermia, immediately contact a health care provider or contact emergency health services. Keep the affected person warm, dry, and indoors while waiting for medical help. To prevent hypothermia, it's helpful to stay warm and dry in cold weather and avoid excessive alcohol consumption. In addition, it's recommended to wear warm, water-repellant protective gear such as jackets, hats, and mittens to prevent body heat from escaping. Finally, when outdoors, stay as dry as you possibly can. This means avoiding activities that would cause you to sweat a lot and being aware of snow entering your mittens or boots.

Now, hyperthermia, on the other hand, typically occurs on humid, hot days (temperatures higher than 98.6 degrees Fahrenheit, or 37 degrees Celsius) during periods of physical exertion, and occurs when the body's internal temperature is over 99 degrees Fahrenheit (37.2 degrees Celsius). While this is may seem similar to a fever, hyperthermia, and fevers are not the same. Unlike hyperthermia, which is caused by a raised internal body temperature, a fever is your body intentionally raising its temperature to fight illness and infection.

During these periods of warm, humid weather, the body is more likely to lose a large amount of fluids and electrolytes. To prevent hyperthermia, stay hydrated, replenish salts lost through sweating, wear loose-fitting clothing to keep dry, and use air-conditioning or fans to keep cool. There are several stages of hyperthermia, ranging from the least to most severe. If you or someone you know appears to be experiencing any of the following symptoms of hyperthermia, contact a health care provider immediately or emergency services:

  • Heat cramps: Muscles feel tense and spasm, pain in muscles of hands, shoulders, or legs
  • Heat exhaustion: Feeling lightheaded, sweating, blurred vision, dizziness, vomiting, or headaches
  • Heatstroke: Similar symptoms as heat exhaustion, but can also include confusion, strange behavior, coma, possible seizures, sweating, urinating very little or not at all

List adapted from Hyperthermia from The Cleveland Clinic. 

While these are serious conditions, they can be avoided by taking the proper precautions and adequately preparing for the climate you're in, whether that's wearing warm clothing outdoors in the winter or wearing cooling layers in the summer heat. Now that you’re prepared in case of hypo- or hyperthermia, you'll know what to do when the intense temperatures tip the scales of your (or a loved one's) health!

Stay warm (or cool),

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Last updated Jan 27, 2023
Originally published Jan 26, 1995