Hyperthermia vs. Hypothermia: Key Differences and Safety Measures

The human body maintains a fairly constant core temperature of around 98.6 °F (37 °C) for healthy functioning of the heart, brain, and other vital organs. If your internal temperature gets too cold or too hot, fatal consequences are possible. This is serious business! Here we’ll explore the dangers of hypothermia and hyperthermia, how to recognize them, and how to avoid them.

What Is the Difference Between Hyperthermia and Hypothermia?

National Weather Service “heat index” forecasts help give you a heads-up on heat danger; if you’re under a heat advisory, the risk of hyperthermia is elevated. Hypothermia, on the other hand, comes with excessive cold, so if there’s a NWS wind chill advisory in effect for your area, be extra vigilant and wrap up well to cover all skin surfaces when going outside.

What Is Hyperthermia?

Hyperthermia is when the body is severely overheated and reaches a temperature of 104 °F (40 °C) or above. When the body gets too hot, there can be life-threatening results without treatment. There are two stages of hyperthermia: heat exhaustion and heatstroke.

Hyperthermia can have a number of causes:

• Prolonged exposure to conditions with a heat index of 105 °F (41 °C) or greater. This means that the air temperature may only be 95 °F (35 °C), but high relative humidity can still mean that conditions for hyperthermia are present. For example, an air temperature of 92 °F (33 °C) with a relative humidity of 60% creates a dangerous level of heat.
• Exposure to sunshine for a prolonged period of time on a hot day.
• Dehydration. It is essential to drink plenty of fluids when outdoors or when exerting oneself in hot weather.
• Excessive time spent in a hot tub or sauna. Generally, the maximum recommended time to spend in either a hot tub or sauna is 30 minutes, followed by proper cooldown and hydration.

Warning Signs of Hyperthermia

Most people have experienced a minor version of heat exhaustion from outdoor chores or exercise on a hot day — you get in the shade, take a break, get hydrated, and you’re OK. If an overheated person continues in a too-hot environment, they can develop heatstroke. This is much more serious than heat exhaustion; it can be fatal. Warning signs of heat exhaustion and stroke include:

• Heat exhaustion: Excessive sweating, skin redness, shortness of breath, weakness, fatigue. Serious if not treated, but not life-threatening in most cases. Moderate hyperthermia begins when the body temperature reaches 101 °F to 104 °F (38 °C to 40 °C).
• Heatstroke: A life-threatening condition that requires immediate medical treatment. Symptoms include hot and dry skin (no perspiration, this is a key warning sign), shortness of breath, dizziness, throbbing headache, nausea. Heatstroke begins when the body core reaches a temperature of 104 °F (40 °C) or greater, and it is very dangerous!

Hyperthermia Treatment

People experiencing hyperthermia need to get cooled off quickly. For heat exhaustion, the sickness can generally be dealt with by placing the person in a shaded or preferably air-conditioned area, giving them cool liquids to drink, and removing any unnecessary clothing.

The situation becomes critical when heatstroke comes into play, and professional medical attention is advised. However, there are things you can do to help a person having a heatstroke while waiting for medical help:

• Call 911 immediately, and then help cool the person down while you wait for assistance.
• Have them strip down to their underwear. This is no time to be modest.
• Place the person in a tub of cold water mixed with ice if possible.
• Put ice or cold, wet towels around the head, neck, armpits, and groin.
• Use fans to circulate air and encourage cooling by evaporation.

Whereas hyperthermia is dealing with overheating, hypothermia, on the other hand, is associated with excessive cold — and is just as dangerous.

What Is Hypothermia?

Hypothermia is a condition in which the body’s core temperature drops below 95 °F (35 °C). At this point, the cooling begins to affect vital systems such as the heart, brain, and internal organs in a negative way. The effect gets more pronounced the colder the body gets.

Hypothermia can be caused by:

• Staying too long in cold water.
• Remaining in wet clothes for an extended period of time.
• Wearing clothes that are too thin for the weather conditions or long-term exposure to cold.
• Prolonged exposure to strong, chilly winds, even if temperatures are above freezing.
• Excessively cold air-conditioning indoors — below 64 °F (18 °C) — especially for older people, who get cold more easily.

Hypothermia happens most quickly when the person is in direct contact with cold water. In fact, the heat transfer from a person’s body to water is 25 times faster than from the body to air!

Warning Signs of Hypothermia

There are three primary stages of hypothermia, each more severe as the body temperature drops:

• Mild hypothermia: Shivering, skin cold to the touch. Not generally life-threatening.
• Moderate hypothermia: Core body temperature is 93 °F to 95 °F (34 °C to 35 °C). This is more serious, and if not corrected, can become life-threatening. Typical signs of moderate hypothermia include dazed consciousness, loss of manual dexterity, slurred speech, uncontrollable shivering, and acting intoxicated or irrational.
• Severe hypothermia: Core body temperature is 92 °F or lower. Death is possible without immediate medical attention. Someone experiencing this urgent level of hypothermia may not be able to walk, their pupils will be dilated, and they will be pale and cold to the touch. Their breathing will be very shallow, and you may not be able to easily find their pulse.

Hypothermia Treatment

People experiencing hypothermia need to get their core body temperature raised as fast as safely possible. A mild case can be safely dealt with by wrapping the person in a heated blanket and giving them warm beverages (and keeping them out of the cold, of course). Doctors have found that for more severe cases, warming the body’s core directly, rather than from outside, works best. Professional medical treatment for serious cases of hypothermia may include:

• Injecting warm fluids directly into the person’s abdominal cavity.
• Injecting warm saline into their bloodstream.
• Using an airway to blow heated air into the lungs.

These procedures sound pretty drastic, and they are. This is why hypothermia warning signs should be heeded early and not ignored. Call 911 if you suspect someone is experiencing severe hypothermia.

Preventing Hypothermia and Hyperthermia

Wearing proper clothing for winter’s outdoor conditions is essential to avoid getting sick from hypothermia. Staying hydrated, taking breaks, and reducing sun exposure is your best defense against hyperthermia and potentially deadly heatstroke. Finally, keep tabs on how the weather affects our health — that knowledge plays a major role in avoiding situations where excessive heat or cold can make you seriously ill. All AcuRite home weather stations are helpful companions to help stay aware of what's brewing outside, whether it's hot or cold, rain or shine!

Steve LaNore is a certified broadcast meteorologist with more than 30 years’ forecasting and technical experience. He has provided meteorological consulting for everything from insurance adjusters to court cases and is a nine-time award-winning author and broadcaster. LaNore has authored two books, available on Amazon. He resides in north Texas near beautiful Lake Texoma.